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set-top boxes panel meters white goods bar graph displays audio/video equipment general description the max6954 is a compact display driver that inter- faces microprocessors to a mix of 7-segment, 14-seg - ment, and 16-segment led displays through an spi-/ qspi?-compatible 4-wire serial interface. the serial interface may be cascaded through multiple devices. the max6954 drives up to 16 digits 7-segment, 8 dig - its 14-segment, 8 digits 16-segment, or 128 discrete leds, while functioning from a supply voltage as low as 2.7v. the driver includes five i/o expander (or gpio) lines, some or all of which may be configured as a key-switch reader, which automatically scans and debounces a matrix of up to 32 switches. included on chip are full 14- and 16-segment ascii 104-character fonts, a hexadecimal font for 7-segment displays, multiplex scan circuitry, anode and cathode driv - ers, and static ram that stores each digit. the maximum segment current for the display digits is set using a single external resistor. digit intensity can be independently adjusted using the 16-step internal digital brightness con - trol. the max6954 includes a low-power shutdown mode, a scan-limit register that allows the user to display from 1 to 16 digits, segment blinking (synchronized across mul - tiple drivers, if desired), and a test mode, which forces all leds on. the led drivers are slew-rate limited to reduce emi. for a 2-wire interfaced version, refer to the max6955 data sheet. an evaluation kit (ev kit) for the max6955 is available. applications features high-speed 26mhz spi/qspi/microwire ? - compatible serial interface 2.7v to 5.5v operation drives up to 16 digits 7-segment, 8 digits 14-segment, 8 digits 16-segment, 128 discrete leds, or a combination of digit types drives common-cathode monocolor and bicolor led displays built-in ascii 104-character font for 14-segment and 16-segment digits and hexadecimal font for 7-segment digits automatic blinking control for each segment 10a (typ) low-power shutdown (data retained) 16-step digit-by-digit digital brightness control display blanked on power-up slew-rate limited segment drivers for lower emi five gpio port pins can be configured as key- switch reader to scan and debounce up to 32 switches with n-key rollover irq output when a key input is debounced 36-pin ssop and 40-pin dip and tqfn packages automotive temperature range standard +denotes a lead-free/rohs-compliant package. *ep = exposed pad. part temp range pin-package max6954aax -40c to +125c 36 ssop max6954apl -40c to +125c 40 pdip max6954atl+ -40c to +125c 40 tqfn-ep* iset osc osc_out blink clk cs din dout 4-wire serial interface ram blink control configuration register character generator rom current source divider/ counter network digit multiplexer pwm brightness control gpio and key-scan control led drivers o0 to o23 p0 to p4 max6954 19-2460; rev 5; 7/14 pin configurations and typical operating circuits appear at end of data sheet. functional diagram qspi is a trademark of motorola, inc. microwire is a registered trademark of national semiconductor corp. ordering information max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
(voltage with respect to gnd.) v+ ........................................................................ -0.3v to +6v all other pins ........................................... -0.3v to (v+ + 0.3v) current o0Co7 sink current ..................................................... 935ma o0Co18 source current ................................................. 55ma din, clk, cs , osc, dout, blink, osc_out, iset .. 20ma p0, p1, p2, p3, p4 ......................................................... 40ma gnd ..................................................................................... 1a continuous power dissipation (t a = +70c) 36-pin ssop (derate at 11.8mw/c above +70c) .... 941mw 40-pin pdip (derate at 16.7mw/c above +70c) ... 1333mw 40-pin tqfn (derate at 37mw/c above +70c) ..... 2963mw operating temperature range (t min to t max ) ............................................. -40c to +125c junction temperature ...................................................... +150c storage temperature range ............................ -65c to +150c lead temperature (soldering, 10s) ................................. +300c (typical operating circuits, v+ = 2.7v to 5.5v, t a = t min to t max , unless otherwise noted.) (note 1) parameter symbol conditions min typ max units operating supply voltage v+ 2.7 5.5 v shutdown supply current i shdn shutdown mode, all digital inputs at v+ or gnd t a = +25c 10 35 a t a = t min to t max 40 operating supply current i+ all segments on, all digits scanned, intensity set to full, internal oscillator, dout open circuit, no display or osc_out load connected t a = +25c 22 30 ma t a = t min to t max 35 master clock frequency f osc osc = rc oscillator, r set = 56k w , c set = 22pf, v+ = 3.3v 4 mhz osc driven externally 1 8 dead clock protection frequency f osc 95 khz osc internal/external detection threshold v osc 1.7 v osc high time t ch 50 ns osc low time t cl 50 ns slow segment blink period f slowblink osc = rc oscillator, r set = 56k w , c set = 22pf, v+ = 3.3v 1 s fast segment blink period f fastblink osc = rc oscillator, r set = 56k w , c set = 22pf, v+ = 3.3v 0.5 s fast or slow segment blink duty cycle 49.5 50.5 % maxim integrated g 2 dc electrical characteristics stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to ab solute maximum rating conditions for extended periods may affect device reliability. absolute maximum ratings www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
(typical operating circuits, v+ = 2.7v to 5.5v, t a = t min to t max , unless otherwise noted.) (note 1) parameter symbol conditions min typ max units segment drive source current i seg v led = 2.2v, v+ = 3.3v t a = +25c -34.5 -40 -46.5 ma segment current slew rate d i seg / d t t a = +25c, v+ = 3.3v 11 ma/s segment drive current matching d i seg t a = +25c, v+ = 3.3v 5 10 % logic inputs and outputs input leakage current din, clk, cs , osc, p0, p1, p2, p3, p4 i ih , i il -1 +1 a 4-wire logic-high input voltage din, clk, cs v ihspi 1.8 v 4-wire logic-low input voltage din, clk, cs v ilspi 0.6 v port logic-high input voltage p0, p1, p2, p3, p4 v ihp 0.7 x v+ v port logic-low input voltage p0, p1, p2, p3, p4 v ilp 0.3 x v+ v port hysteresis voltage p0, p1, p2, p3, p4 d v ip 0.03 x v+ v port input pullup current from v+ i ipu p0 to p3 configured as keyscan input, v+ = 3.3v 75 a port output low voltage v olp i sink = 8ma 0.3 0.5 v blink output low voltage v olbk i sink = 0.6ma 0.1 0.3 v dout output high voltage v ohdo i source = 1.6ma v+ - 0.2 v dout output low voltage v oldo i sink = 1.6ma 0.2 v osc_out output high voltage v ohosc i source = 1.6ma v+ - 0.4 v osc_out output low voltage v olosc i sink = 1.6ma 0.4 v maxim integrated g 3 dc electrical characteristics (continued) www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
(v+ = 3.3v, led forward voltage = 2.4v, typical application circuit, t a = +25c, unless otherwise noted.) note 1: all parameters tested at t a = +25c. specifications over temperature are guaranteed by design. ( typical operating circuits , v+ = 2.7v to 5.5v, t a = t min to t max , unless otherwise noted.) (note 1) parameter symbol conditions min typ max units clk clock period t cp 38.4 ns clk pulse width high t ch 16 ns clk pulse width low t cl 16 ns cs fall to clk rise setup time t css 9.5 ns clk rise to cs rise hold time t csh 0 ns din setup time t ds 9.5 ns din hold time t dh 0 ns output data propagation delay t do v+ = 3.0v to 5.5v 19 ns v+ = 2.7v 25 dout output rise and fall times t ft c load = 10pf, v+ = 3.0v to 5.5v 10 ns minimum cs pulse high t csw 19.5 ns 100ns/div osc: 500mv/div osc_out: 2v/div max6954 toc03 osc 0v 0v osc_out internal oscillator waveform at osc and osc_out pins r set = 56k? c set = 22pf internal oscillator frequency vs. supply voltage max6954 toc02 supply voltage (v) oscillator frequency (mhz) 5.0 4.5 4.0 3.5 3.0 3.8 4.2 4.4 3.6 2.5 5.5 r set = 56k? c set = 22pf 4.0 internal oscillator frequency vs. temperature max6954 toc01 temperature ( c) oscillator frequency (mhz) 110 80 50 20 -10 3.8 4.0 4.2 4.4 3.6 -40 r set = 56k? c set = 22pf maxim integrated g 4 typical operating characteristics timing characteristics www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
(v+ = 3.3v, led forward voltage = 2.4v, typical application circuit, t a = +25c, unless otherwise noted.) port input pullup current vs. temperature max6954 toc08 temperature ( c) key-scan source current (ma) 110 50 80 20 -10 0.05 0.10 0.15 0.20 0.25 0.30 0 -40 v cc = 3.3v v cc = 2.5v v cc = 5.5v output = high v port = 1.4v gpio sink current vs. temperature max6954 toc07 temperature ( c) gpio sink current (ma) 110 50 80 20 -10 5 10 15 20 25 30 35 40 45 0 -40 v cc = 3.3v v cc = 2.5v v cc = 5.5v output = low v port = 0.6v 400s/div key_a: 1v/div irq: 2v/div max6954 toc09 key_a 0v 0v irq keyscan operation (key_a and irq) 1v/div 200s/div max6954 toc06 o0 o18 waveform at pins o0 and o18, maximum intensity 0v 0v segment source current vs. supply voltage max6954 toc05 supply voltage (v) current normalized to 40ma 5.0 4.5 4.0 3.5 3.0 0.94 0.98 1.00 1.02 0.92 2.5 5.5 v led = 1.8v 0.96 dead clock oscillator frequency vs. supply voltage max6954 toc04 supply voltage (v) oscillator frequency (khz) 5.0 4.5 4.0 3.5 3.0 85 95 105 110 80 2.5 5.5 r set = 56k? osc = gnd 100 90 maxim integrated g 5 typical operating characteristics (continued) www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
detailed description the max6954 is a serially interfaced display driver that can drive up to 16 digits 7-segment, 8 digits 14-segment, 8 digits 16-segment, 128 discrete leds, or a combination of these display types. table 1 shows the drive capability of the max6954 for monocolor and bicolor displays. the max6954 includes 104-character ascii font maps for 14-segment and 16-segment displays, as well as the hexadecimal font map for 7-segment displays. the characters follow the standard ascii font, with the addi - tion of the following common symbols: , , , , , , , and . seven bits represent the 104-character font map; an 8th bit is used to select whether the decimal point (dp) is lit. seven-segment led digits may be con- trolled directly or use the hexadecimal font. direct seg - ment control allows the max6954 to be used to drive bar graphs and discrete led indicators. tables 2, 3, and 4 list the connection schemes for 16-, 14-, and 7-segment digits, respectively. the letters in tables 2, 3, and 4 correspond to the segment labels shown in figure 1. (for applications that require mixed display types, see tables 37C40.) serial interface the max6954 communicates through an spi-compati- ble 4-wire serial interface. the interface has three inputs: clock (clk), chip select ( cs ), and data in (din), and one output, data out (dout). cs must be low to pin name function ssop pdip tqfn-ep 1, 2, 34, 35, 36 1, 2, 38, 39, 40 36, 37, 33, 34, 35 p0Cp4 general-purpose i/o ports (gpios). gpio can be configured as logic inputs or open-drain outputs. enabling key scanning configures some or all ports p0Cp3 as key-switch matrix inputs with internal pullup and port p4 as irq output. 3 3 38 cs chip-select input. serial data is loaded into the shift register while cs is low. the most recent 16 bits of data latch on cs s rising edge. 4 4 39 dout serial-data output. the data into din is valid at dout 15.5 clock cycles later. use this pin to daisy-chain several devices or allow data readback. output is push-pull. 5 5 40 clk serial-clock input. on clks rising edge, data shifts into the internal shift register. on clks falling edge, data is clocked out of dout. clk is active only while cs is low. 6 6 1 din serial-data input. data from din loads into the internal 16-bit shift register on clks rising edge. 7C15, 22C31 7C15, 26C35 2C10, 21C30 o0Co18 digit/segment drivers. when acting as digit drivers, outputs o0 to o7 sink current from the display common cathodes. when acting as segment drivers, o0 to o18 source current to the display anodes. o0 to o18 are high impedance when not being used as digit or segment drivers. 16, 18 17, 18, 20 12, 13, 15 gnd ground 17 19 14 iset segment current setting. connect iset to gnd through series resistor r set to set the peak current. 19, 21 21, 23, 24 16, 18, 19 v+ positive supply voltage. bypass v+ to gnd with a 47f bulk capacitor and a 0.1f ceramic capacitor. 20 22 17 osc multiplex clock input. to use internal oscillator, connect capacitor c set from osc to gnd. to use external clock, drive osc with a 1mhz to 8mhz cmos clock. 32 36 31 blink blink clock output. output is open drain. 33 37 32 osc_out clock output. osc_out is a buffered clock output to allow easy blink synchronization of multiple max6954s. output is push-pull. 16, 25 11, 20 n.c. not connected internally ep exposed pad (tqfn package only). internally connected to gnd. connect to a large ground plane to maximize thermal performance. maxim integrated 6 pin description www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
clock data into or out of the device, and din must be stable when sampled on the rising edge of clk. dout is stable on the rising edge of clk. note that while the spi protocol expects dout to be high impedance when the max6954 is not being accessed, dout on the max6954 is never high impedance. clk and din may be used to transmit data to other peripherals. the max6954 ignores all activity on clk and din except when cs is low. control and operation using the 4-wire interface controlling the max6954 requires sending a 16-bit word. the first byte, d15 through d8, is the command, and the second byte, d7 through d0, is the data byte (table 5). connecting multiple max6954s to the 4-wire bus multiple max6954s may be daisy-chained by connect- ing the dout of one device to the din of the next, and driving clk and cs lines in parallel (figure 2). data at din propagates through the internal shift registers and appears at dout 15.5 clock cycles later, clocked out on the falling edge of clk. when sending commands to daisy-chained max6954s, all devices are accessed at the same time. an access requires (16 x n) clock cycles, where n is the number of max6954s connected together. to update just one device in a daisy-chain, the user can send the no-op command (0x00) to the others. figure 3 is the max6954 timing diagram. the max6954 is written to using the following sequence: 1) take clk low. 2) take cs low. this enables the internal 16-bit shift register. 3) clock 16 bits of data into din, d15 frst to d0 last, observing the setup and hold times. bit d15 is low, indicating a write command. 4) take cs high (while clk is still high after clocking in the last data bit). 5) take clk low. 6) figure 4 shows a write operation when 16 bits are transmitted. if fewer or greater than 16 bits are clocked into the max6954 between taking cs low and taking cs high again, the max6954 stores the last 16 bits received, including the previous transmission(s). the general case is when n bits (where n > 16) are transmitted to the max6954. the last bits are comprising bits {n-15} to {n}, are retained, and are parallel loaded into the 16-bit latch as bits d15 to d0, respectively (figure 5). table 1. max6954 drive capability figure 1. segment labeling for 7-segment display, 14-segment display, and 16-segment display display type 7 segment (16-character hexadecimal font) 14 segment/ 16 segment (104-character ascii font map) discrete leds (direct control) monocolor 16 8 128 bicolor 8 4 64 1dp 2dp f b e c d1 a1 i l g1 g2 h j m k a2 d2 dp dp 1a 1g 1f 1b 1e 1c 1d 2a 2g 2f 2b 2e 2c 2d f b e c d a i l g1 g2 h j m k maxim integrated 7 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
reading device registers any register data within the max6954 may be read by sending a logic-high to bit d15. the sequence is: 1) take clk low. 2) take cs low. this enables the internal 16-bit shift register. 3) clock 16 bits of data into din, d15 frst to d0 last. d15 is high, indicating a read command and bits d14 through d8 contain the address of the register table 5. serial-data format (16 bits) *each cathode driver output (cc0-cc7) connects to two digit common cathode pins. table 4. connection scheme for sixteen 7-segment digits table 3. connection scheme for eight 14-segment digits table 2. connection scheme for eight 16-segment digits d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 r/ w address msb data lsb digit* o0 o1 o2 o3 o4 o5 o6 o7 o8 o9 o10 o11 o12 o13 o14 o15 o16 o17 o18 0, 0a cc0 1a 1b 1c 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g 2dp 1, 1a cc1 1a 1b 1c 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g 2dp 2, 2a 1a cc2 1b 1c 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g 2dp 3, 3a 1a cc3 1b 1c 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g 2dp 4, 4a 1a 1b 1c cc4 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g 2dp 5, 5a 1a 1b 1c cc5 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g 2dp 6, 6a 1a 1b 1c 1d 1dp cc6 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g 2dp 7, 7a 1a 1b 1c 1d 1dp cc7 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g 2dp digit o0 o1 o2 o3 o4 o5 o6 o7 o8 o9 o10 o11 o12 o13 o14 o15 o16 o17 o18 0 cco a b c d e f g1 g2 h i j k l m dp 1 cc1 a b c d e f g1 g2 h i j k l m dp 2 a cc2 b c d e f g1 g2 h i j k l m dp 3 a cc3 b c d e f g1 g2 h i j k l m dp 4 a b c cc4 d e f g1 g2 h i j k l m dp 5 a b c cc5 d e f g1 g2 h i j k l m dp 6 a b c d cc6 e f g1 g2 h i j k l m dp 7 a b c d cc7 e f g1 g2 h i j k l m dp digit o0 o1 o2 o3 o4 o5 o6 o7 o8 o9 o10 o11 o12 o13 o14 o15 o16 o17 o18 0 cco a1 a2 b c d1 d2 e f g1 g2 h i j k l m dp 1 cc1 a1 a2 b c d1 d2 e f g1 g2 h i j k l m dp 2 a1 a2 cc2 b c d1 d2 e f g1 g2 h i j k l m dp 3 a1 a2 cc3 b c d1 d2 e f g1 g2 h i j k l m dp 4 a1 a2 b c cc4 d1 d2 e f g1 g2 h i j k l m dp 5 a1 a2 b c cc5 d1 d2 e f g1 g2 h i j k l m dp 6 a1 a2 b c d1 d2 cc6 e f g1 g2 h i j k l m dp 7 a1 a2 b c d1 d2 cc7 e f g1 g2 h i j k l m dp maxim integrated 8 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
to read. bits d7 to d0 contain dummy data, which is discarded. 4) take cs high (while clk is still high after clocking in the last data bit), positions d7 through d0 in the shift register are now loaded with the register data addressed by bits d15 through d8. 5) take clk low. 6) issue another read or write command (which can be a no-op), and examine the bit stream at dout; the second 8 bits are the contents of the register addressed by bits d14 through d8 in step 3. digit type registers the max6954 uses 32 digit registers to store the char- acters that the user wishes to display. these digit regis - ters are implemented with two planes, p0 and p1. each digit is represented by 2 bytes of memory, 1 byte in plane p0 and the other in plane p1. the digit registers are mapped so that a digits data can be updated in plane p0, plane p1, or both planes at the same time (table 6). if the blink function is disabled through the blink enable bit e (table 19) in the configuration register, then the digit register data in plane p0 is used to multiplex the display. the digit register data in p1 is not used. if the blink function is enabled, then the digit register data in both plane p0 and plane p1 are alternately used to mul - tiplex the display. blinking is achieved by multiplexing the led display using data plane p0 and plane p1 on alternate phases of the blink clock (table 20). the data in the digit registers does not control the digit segments directly for 14- and 16-segment displays. instead, the register data is used to address a charac- ter generator that stores the data for the 14- and 16- segment fonts (tables 7 and 8). the lower 7 bits of the digit data (d6 to d0) select the character from the font. figure 3. timing diagram figure 2. max6954 daisy-chain connection t css t cl t ch t cp t csh t csw t ds t dh d15 clk din cs d14 d1 d0 d15 t do dout max6954 dout microcontroller clk din max6954 max6954 clk din cs dout clk din cs dout clk din cs dout cs maxim integrated 9 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
the most significant bit of the register data (d7) con- trols the dp segment of the digits; it is set to 1 to light dp, and to zero to leave dp unlit (table 9). for 7-segment displays, the digit plane data register can be used to address a character generator, which contains the data of a 16-character font containing the hexadecimal font. the decode mode register can be used to disable the character generator and allow the segments to be controlled directly. table 10 shows the one-to-one pairing of each data bit to the appropriate segment line in the digit plane data registers. the hexa - decimal font is decoded according to table 11. the digit-type register configures the display driver for various combinations of 14-segment digits, 16-segment digits, and/or pairs, or 7-segment digits. the function of this register is to select the appropriate font for each digit and route the output of the font to the appropriate max6954 driver output pins. the max6954 has four digit drive slots. a slot can be filled with various combi - nations of monocolor and bicolor 16-segment displays, 14-segment displays, or two 7-segment displays. each pair of bits in the register corresponds to one of the four digit drive slots, as shown in table 12. each bit also cor- responds to one of the eight common-cathode digit drive outputs, cc0 to cc7. when using bicolor digits, the anode connections for the two digits within a slot are always the same. this means that a slot correctly drives two monocolor or one bicolor 14- or 16-segment digit. the digit type register can be written, but cannot be read. examples of configuration settings required for some display digit combinations are shown in table 13. 7-segment decode-mode register in 7-segment mode, the hexadecimal font can be dis- abled (table 14). the decode-mode register selects between hexadecimal code or direct control for each of eight possible pairs of 7-segment digits. each bit in the register corresponds to one pair of digits. the digit pairs are {digit 0, digit 0a} through {digit 7, digit 7a}. disabling decode mode allows direct control of the 16 leds of a dual 7-segment display. direct control mode can also be used to drive a matrix of 128 discrete leds. figure 5. transmission of more than 16 bits to the max6954 figure 4. transmission of 16 bits to the max6954 cs clk din bit 1 bit 2 n-9 n-8 n-7 n-6 n-5 n-4 n-3 n-2 dout n-15 n-15 n-14 n-13 n-12 n-11 n-10 n-1 n-31 n-30 n-29 n-28 n-27 n-26 n-25 n-24 n-23 n-22 n-21 n-20 n-19 n-18 n-17 n-16 n cs clk din d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 dout d15 = 0 maxim integrated 10 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
a logic-high selects hexadecimal decoding, while a logic-low bypasses the decoder. when direct control is selected, the data bits d7 to d0 correspond to the seg - ment lines of the max6954. write x0010000 to blank all segments in hexadecimal decode mode. display blink mode the display blinking facility, when enabled, makes the driver flip automatically between displaying the digit reg - ister data in planes p0 and p1. if the digit register data for any digit is different in the two planes, then that digit appears to flip between two characters. to make a char - acter appear to blink on or off, write the character to one plane, and use the blank character (0x20) for the other plane. once blinking has been configured, it continues automatically without further intervention. blink speed the blink speed is determined by the frequency of the multiplex clock, osc, and by the setting of the blink rate selection bit b (table 18) in the configuration register. the blink rate selection bit b sets either fast or slow blink speed for the whole display. initial power-up on initial power-up, all control registers are reset, the display is blanked, intensities are set to minimum, and shutdown is enabled (table 15). confguration register the configuration register is used to enter and exit shut - down, select the blink rate, globally enable and disable the blink function, globally clear the digit data, select between global or digit-by-digit control of intensity, and reset the blink timing (tables 16C19 and 21C24). the configuration register contains 7 bits: s bit selects shutdown or normal operation (read/write). b bit selects the blink rate (read/write). e bit globally enables or disables the blink function (read/write). t bit resets the blink timing (data is not storedtran - sient bit). r bit globally clears the digit data for both planes p0 and p1 for all digits (data is not storedtransient bit). i bit selects between global or digit-by-digit control of intensity (read/write). p bit returns the current phase of the blink timing (read onlya write to this bit is ignored). character generator font mapping the font is composed of 104 characters in rom. the lower 7 bits of the 8-bit digit register represent the char - acter selection. the most significant bit, shown as x in the rom map of tables 7 and 8, is 1 to light the dp segment and zero to leave the dp segment unlit. the character map follows the standard ascii font for 96 characters in the x0101000 through x1111111 range. the first 16 characters of the 16-segment rom map cover 7-segment displays. these 16 characters are numeric 0 to 9 and characters a to f (i.e., the hexa - decimal set). multiplex clock and blink timing the osc pin can be fitted with capacitor c set to gnd to use the internal rc multiplex oscillator, or driven by an external clock to set the multiplex clock frequency and blink rate. the multiplex clock frequency determines the frequency that the complete display is updated. with osc at 4mhz, each display digit is enabled for 200s. the internal rc oscillator uses an external resistor, r set , and an external capacitor, c set , to set the oscillator fre - quency. the suggested values of r set (56k w ) and c set (22pf) set the oscillator at 4mhz, which makes the blink frequency 0.5hz or 1hz. the external clock is not required to have a 50:50 duty cycle, but the minimum time between transitions must be 50ns or greater and the maximum time between transitions must be 750ns. the on-chip oscillator may be accurate enough for appli - cations using a single device. if an exact blink rate is required, use an external clock ranging between 1mhz and 8mhz to drive osc. the osc inputs of multiple max6954s can be tied together to a common external clock to make the devices blink at the same rate. the relative blink phasing of multiple max6954s can be syn - chronized by setting the t bit in the control register for all the devices in quick succession. if the serial interfaces of multiple max6954s are daisy-chained by connecting the dout of one device to the din of the next, then synchro - nization is achieved automatically by updating the config - uration register for all devices simultaneously. figure 6 is the multiplex timing diagram. osc_out output the osc_out output is a buffered copy of either the internal oscillator clock or the clock driven into the osc pin if the external clock has been selected. the feature is useful if the internal oscillator is used, and the user wishes to synchronize other max6954s to the same blink frequency. the oscillator is disabled while the max6954 is in shutdown. maxim integrated 11 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
scan-limit register the scan-limit register sets how many 14-segment digits or 16-segment digits or pairs of 7-segment digits are displayed, from 1 to 8. a bicolor digit is connected as two monocolor digits. the scan register also limits the number of keys that can be scanned. since the number of scanned digits affects the display brightness, the scan-limit register should not be used to blank portions of the display (such as leading-zero sup - pression). table 25 shows the scan-limit register format. intensity registers digital control of display brightness is provided and can be managed in one of two ways: globally or individually. global control adjusts all digits together. individual control adjusts the digits separately. the default method is global brightness control, which is selected by clearing the global intensity bit (i data bit d6) in the configuration register. this brightness setting applies to all display digits. the pulse-width modulator is then set by the lower nibble of the global intensity reg - ister, address 0x02. the modulator scales the average segment current in 16 steps from a maximum of 15/16 down to 1/16 of the peak current. the minimum interdigit blanking time is set to 1/16 of a cycle. when using bicolor digits, 256 color/brightness combinations are available. individual brightness control is selected by setting the global intensity bit (i data bit d6) in the configuration reg - ister. the pulse-width modulator is now no longer set by the lower nibble of the global intensity register, address 0x02, and the data is ignored. individual digital control of display brightness is now provided by a separate pulse- width modulator setting for each digit. each digit is con - trolled by a nibble of one of the four intensity registers: intensity10, intensity32, intensity54, and intensity76 for all display types, plus intensity10a, intensity32a, intensi - ty54a, and intensity76a for the extra eight digits possible when 7-segment displays are used. the data from the relevant register is used for each digit as it is multiplexed. the modulator scales the average segment current in 16 steps in exactly the same way as global intensity adjust - ment. table 26 shows the global intensity register format, table 27 shows individual segment intensity registers, table 28 is the even individual segment intensity format, and table 29 is the odd individual segment intensity format. gpio and key scanning the max6954 feature five general-purpose input/output (gpio) ports: p0 to p4. these ports can be individual - ly enabled as logic inputs or open-drain logic outputs. the gpio ports are not debounced when configured as inputs. the ports can be read and the outputs set using the 4-wire interface. some or all of the five ports can be configured to per - form key scanning of up to 32 keys. ports p0 to p4 are renamed key_a, key_b, key_c, key_d, and irq, respectively, when used for key scanning. the full key-scanning configuration is shown in figure 7. table 30 is the gpio data register. one diode is required per key switch. these diodes can be common-anode dual diodes in sot23 packages, such as the baw56. sixteen diodes would be required for the maximum 32-key configuration. the max6954 can only scan the maximum 32 keys if the scan-limit register is set to scan the maximum eight digits. if the max6954 is driving fewer digits, then a maximum of (4 x n) switches can be scanned, where n is the number of digits set in the scan-limit register. for example, if the max6954 is driving four 14-segment digits cathode driv - ers o0 to o3 are used. only 16 keys can be scanned in this configuration; the switches shown connected to o4 through o7 are not read. if the user wishes to scan fewer than 32 keys, then fewer scan lines can be configured for key scanning. the unused key_x ports are released back to their original gpio functionality. if key scanning is enabled, regardless of the number of keys being scanned, p4 is always con - figured as irq (table 31). the key-scanning circuit utilizes the leds common-cath - ode driver outputs as the key-scan drivers. o0 to 07 go low for nominally 200s (with osc = 4mhz) in turn as the displays are multiplexed. by varying the oscilla - tor frequency, the debounce time changes, though key scanning still functions. key_x inputs have internal pullup resistors that allow the key condition to be tested. the key_x input is low during the appropriate digit multiplex period when the key is pressed. the timing diagram of figure 8 shows the normal situation where all eight led cathode drivers are used. maxim integrated 12 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
*do not write to register. register address (command byte) hex code d15 d14 d13 d12 d11 d10 d9 d8 no-op r/ w 0 0 0 0 0 0 0 0x00 decode mode r/ w 0 0 0 0 0 0 1 0x01 global intensity r/ w 0 0 0 0 0 1 0 0x02 scan limit r/ w 0 0 0 0 0 1 1 0x03 configuration r/ w 0 0 0 0 1 0 0 0x04 gpio data r/ w 0 0 0 0 1 0 1 0x05 port configuration r/ w 0 0 0 0 1 1 0 0x06 display test r/ w 0 0 0 0 1 1 1 0x07 write key_a mask read key_a debounce r/ w 0 0 0 1 0 0 0 0x08 write key_b mask read key_b debounce r/ w 0 0 0 1 0 0 1 0x09 write key_c mask read key_c debounce r/ w 0 0 0 1 0 1 0 0x0a write key_d mask read key_d debounce r/ w 0 0 0 1 0 1 1 0x0b write digit type read key_a pressed r/ w 0 0 0 1 1 0 0 0x0c read key_b pressed* 1 0 0 0 1 1 0 1 0x0d read key_c pressed* 1 0 0 0 1 1 1 0 0x0e read key_d pressed* 1 0 0 0 1 1 1 1 0x0f intensity 10 r/ w 0 0 1 0 0 0 0 0x10 intensity 32 r/ w 0 0 1 0 0 0 1 0x11 intensity 54 r/ w 0 0 1 0 0 1 0 0x12 intensity 76 r/ w 0 0 1 0 0 1 1 0x13 intensity 10a (7 segment only) r/ w 0 0 1 0 1 0 0 0x14 intensity 32a (7 segment only) r/ w 0 0 1 0 1 0 1 0x15 intensity 54a (7 segment only) r/ w 0 0 1 0 1 1 0 0x16 intensity 76a (7 segment only) r/ w 0 0 1 0 1 1 1 0x17 digit 0 plane p0 r/ w 0 1 0 0 0 0 0 0x20 digit 1 plane p0 r/ w 0 1 0 0 0 0 1 0x21 digit 2 plane p0 r/ w 0 1 0 0 0 1 0 0x22 digit 3 plane p0 r/ w 0 1 0 0 0 1 1 0x23 digit 4 plane p0 r /w 0 1 0 0 1 0 0 0x24 digit 5 plane p0 r/ w 0 1 0 0 1 0 1 0x25 digit 6 plane p0 r/ w 0 1 0 0 1 1 0 0x26 digit 7 plane p0 r/ w 0 1 0 0 1 1 1 0x27 digit 0a plane p0 (7 segment only) r/ w 0 1 0 1 0 0 0 0x28 digit 1a plane p0 (7 segment only) r/ w 0 1 0 1 0 0 1 0x29 digit 2a plane p0 (7 segment only) r/ w 0 1 0 1 0 1 0 0x2a digit 3a plane p0 (7 segment only) r/ w 0 1 0 1 0 1 1 0x2b maxim integrated 13 table 6. register address map www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 6. register address map (continued) register address (command byte) hex code d15 d14 d13 d12 d11 d10 d9 d8 digit 4a plane p0 (7 segment only) r/ w 0 1 0 1 1 0 0 0x2c digit 5a plane p0 (7 segment only) r/ w 0 1 0 1 1 0 1 0x2d digit 6a plane p0 (7 segment only) r/ w 0 1 0 1 1 1 0 0x2e digit 7a plane p0 (7 segment only) r/ w 0 1 0 1 1 1 1 0x2f digit 0 plane p1 r/ w 1 0 0 0 0 0 0 0x40 digit 1 plane p1 r/ w 1 0 0 0 0 0 1 0x41 digit 2 plane p1 r/ w 1 0 0 0 0 1 0 0x42 digit 3 plane p1 r/ w 1 0 0 0 0 1 1 0x43 digit 4 plane p1 r/ w 1 0 0 0 1 0 0 0x44 digit 5 plane p1 r/ w 1 0 0 0 1 0 1 0x45 digit 6 plane p1 r/ w 1 0 0 0 1 1 0 0x46 digit 7 plane p1 r/ w 1 0 0 0 1 1 1 0x47 digit 0a plane p1 (7 segment only) r/ w 1 0 0 1 0 0 0 0x48 digit 1a plane p1 (7 segment only) r/ w 1 0 0 1 0 0 1 0x49 digit 2a plane p1 (7 segment only) r/ w 1 0 0 1 0 1 0 0x4a digit 3a plane p1 (7 segment only) r/ w 1 0 0 1 0 1 1 0x4b digit 4a plane p1 (7 segment only) r/ w 1 0 0 1 1 0 0 0x4c digit 5a plane p1 (7 segment only) r/ w 1 0 0 1 1 0 1 0x4d digit 6a plane p1 (7 segment only) r/ w 1 0 0 1 1 1 0 0x4e digit 7a plane p1 (7 segment only) r/ w 1 0 0 1 1 1 1 0x4f write digit 0 planes p0 and p1 with same data, reads as 0x00 r/ w 1 1 0 0 0 0 0 0x60 write digit 1 planes p0 and p1 with same data, reads as 0x00 r/ w 1 1 0 0 0 0 1 0x61 write digit 2 planes p0 and p1 with same data, reads as 0x00 r/ w 1 1 0 0 0 1 0 0x62 write digit 3 planes p0 and p1 with same data, reads as 0x00 r/ w 1 1 0 0 0 1 1 0x63 write digit 4 planes p0 and p1 with same data, reads as 0x00 r/ w 1 1 0 0 1 0 0 0x64 write digit 5 planes p0 and p1 with same data, reads as 0x00 r/ w 1 1 0 0 1 0 1 0x65 write digit 6 planes p0 and p1 with same data, reads as 0x00 r/ w 1 1 0 0 1 1 0 0x66 write digit 7 planes p0 and p1 with same data, reads as 0x00 r/ w 1 1 0 0 1 1 1 0x67 write digit 0a planes p0 and p1 with same data (7 segment only), reads as 0x00 r/ w 1 1 0 1 0 0 0 0x68 write digit 1a planes p0 and p1 with same data (7 segment only), reads as 0x00 r/ w 1 1 0 1 0 0 1 0x69 maxim integrated 14 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
the timing in figure 8 loops over time, with 32 keys experiencing a full key-scanning debounce over typi- cally 25.6ms. four keys are sampled every 1.6ms, or every multiplex cycle. if at least one key that was not previously pressed is found to have been pressed dur- ing both sampling periods, then that key press is debounced, and an interrupt is issued. the key-scan circuit detects any combination of keys being pressed during each debounce cycle (n-key rollover). port confguration register the port configuration register selects how the five port pins are used. the port configuration register format is described in table 32. key mask registers the key_a mask, key_b mask, key_c mask, and key_d mask write-only registers (table 33) configure the key-scanning circuit to cause an interrupt only when selected (masked) keys have been debounced. each bit in the register corresponds to one key switch. the bit is clear to disable interrupt for the switch, and set to enable interrupt. keys are always scanned (if enabled through the port configuration register), regardless of the setting of these interrupt bits, and the key status is stored in the appropriate key_x pressed register. key debounced registers the key_a debounced, key_b debounced, key_c debounced, and key_d debounced read-only registers (table 34) show which keys have been detected as debounced by the key-scanning circuit. each bit in the register corresponds to one key switch. the bit is set if the switch has been correctly debounced since the register was read last. reading a debounced register clears that register (after the data has been read) so that future keys pressed can be identified. if the debounced registers are not read, the key-scan data accumulates. however, as there is no fifo in the max6954, the user is not able to determine key order, or whether a key has been pressed more than once, unless the debounced key status registers are read after each interrupt, and before the next key-scan cycle. reading any of the four debounced registers clears the irq output. if a key is pressed and held down, the key is reported as debounced (and irq issued) only once. the key must be detected as released by the key-scan- ning circuit, before it debounces again. if the debounced registers are being read in response to the irq being asserted, then the user should generally read all four registers to ensure that all the keys that were detected by the key-scanning circuit are discovered. key pressed registers the key_a pressed, key_b pressed, key_c pressed and key_d pressed read-only registers (table 35)show which keys have been detected as pressed by the key-scanning circuit during the last test. each bit in the register corresponds to one key switch. the bit is set if the switch has been detected as pressed by the key-scanning circuit during the last test. note: unused register bits read as zero. table 6. register address map (continued) register address (command byte) hex code d15 d14 d13 d12 d11 d10 d9 d8 write digit 2a planes p0 and p1 with same data (7 segment only), reads as 0x00 r/ w 1 1 0 1 0 1 0 0x6a write digit 3a planes p0 and p1 with same data (7 segment only), reads as 0x00 r/ w 1 1 0 1 0 1 1 0x6b write digit 4a planes p0 and p1 with same data (7 segment only), reads as 0x00 r/ w 1 1 0 1 1 0 0 0x6c write digit 5a planes p0 and p1 with same data (7 segment only), reads as 0x00 r/ w 1 1 0 1 1 0 1 0x6d write digit 6a planes p0 and p1 with same data (7 segment only), reads as 0x00 r/ w 1 1 0 1 1 1 0 0x6e write digit 7a planes p0 and p1 with same data (7 segment only), reads as 0x00 r /w 1 1 0 1 1 1 1 0x6f maxim integrated 15 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
figure 6. multiplex timing diagram (osc = 4mhz) digit 1 one complete 1.6ms multiplex cycle around 8 digits digit 0's 200 s multiplex timeslot digit 0 200s digit 2 digit 3 digit 4 digit 5 digit 6 digit 7 start of next cycle low 2/16th 1/16th (min on) high-z high-z low 3/16th high-z low 4/16th high-z low 5/16th high-z low 6/16th high-z low 7/16th high-z low 8/16th high-z low 9/16th high-z low 10/16th high-z low 11/16th high-z low 12/16th high-z low 13/16th high-z low 14/16th high-z low 15/16th high-z low 15/16th high-z (max on) high-z high-z current source enabled minimum 12.5s interdigit blanking interval high-z anode (lit) digit 0 cathode driver intensity settings anode (unlit) maxim integrated 16 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
figure 8. key-scan timing diagram figure 7. key-scanning configuration led output o0 led output o1 led output o2 led output o3 led output o4 led output o5 led output o6 led output o7 12.5s to 187.5s digit period 1.6ms multiplex cycle 1 1.6ms multiplex cycle 2 1.6ms multiplex cycle 8 the first half of a 25.6ms key-scan cycle 1.6ms multiplex cycle 8 the second half of a 25.6ms key-scan cycle 1.6ms multiplex cycle 1 start of next key-scan cycle first test of key switches second test of key switches interrupt asserted if required debounce register updated c a a b d e sw a0 sw a1 sw a2 sw a3 sw a4 sw a5 sw a6 sw a7 p0 v cc led output o0 led output o1 led output o2 led output o3 led output o4 led output o5 led output o6 led output o7 p1 p2 p3 p4 microcontroller interrupt sw b0 sw b1 sw b2 sw b3 sw b4 sw b5 sw b6 sw b7 sw c0 sw c1 sw c2 sw c3 sw c4 sw c5 sw c6 sw c7 sw d0 sw d1 sw d2 sw d3 sw d4 sw d5 sw d6 sw d7 maxim integrated 17 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
the bit is cleared if the switch has not been detected as pressed by the key-scanning circuit during the last test. reading a pressed register does not clear that register or clear the irq output. display test register the display test register (table 36) operates in two modes: normal and display test. display test mode turns all leds on (including dps) by overriding, but not altering, all controls and digit registers (including the shutdown register), except for the digit-type register and the gpio configuration register. the duty cycle, while in display test mode, is 7/16 (see the choosing supply voltage to minimize power dissipation section). selecting external components r set and c set to set oscillator frequency and peak segment current the rc oscillator uses an external resistor, r set , and an external capacitor, c set , to set the frequency, f osc . the allowed range of f osc is 1mhz to 8mhz. r set also sets the peak segment current. the recommended val - ues of r set and c set set the oscillator to 4mhz, which makes the blink frequencies selectable between 0.5hz and 1hz. the recommended value of r set also sets the peak current to 40ma, which makes the segment current adjustable from 2.5ma to 37.5ma in 2.5ma steps. i seg = kl / r set ma f osc = kf / (r set x c set ) mhz where: k l = 2240 k f = 5376 r set = external resistor in k w c set = external capacitor in pf c stray = stray capacitance from osc pin to gnd in pf, typically 2pf the recommended value of r set is 56k w and the rec- ommended value of c set is 22pf. the recommended value or r set is the minimum allowed value, since it sets the display driver to the maximum allowed peak segment current. r set can be set to a higher value to set the segment current to a lower peak value where desired. the user must also ensure that the peak current specifications of the leds connected to the driver are not exceeded. the effective value of rset includes not only the actual external capacitor used, but also the stray capacitance from osc to gnd. this capacitance is usually in the 1pf to 5pf range, depending on the layout used. applications information driving bicolor leds bicolor digits group a red and a green die together for each display element, so that the element can be lit red or green (or orange), depending on which die (or both) is lit. the max6954 allows each segments current to be set individually from the 1/16th (minimum current and led intensity) to 15/16th (maximum current and led intensity), as well as off (zero current). thus, a bicolor (red-green) segment pair can be set to 256 color/intensity combinations. choosing supply voltage to minimize power dissipation the max6954 drives a peak current of 40ma into leds with a 2.2v forward-voltage drop when operated from a supply voltage of at least 3.0v. the minimum voltage drop across the internal led drivers is therefore (3.0v - 2.2v) = 0.8v. if a higher supply voltage is used, the dri- ver absorbs a higher voltage, and the drivers power dissipation increases accordingly. however, if the leds used have a higher forward voltage drop than 2.2v, the supply voltage must be raised accordingly to ensure that the driver always has at least 0.8v of headroom. the voltage drop across the drivers with a nominal 5v supply (5.0v - 2.2v) = 2.8v is nearly 3 times the drop across the drivers with a nominal 3.3v supply (3.3v - 2.2v) = 1.1v. in most systems, consumption is an important design criterion, and the max6954 should be operated from the systems 3.3v nominal supply. in other designs, the lowest supply voltage may be 5v. the issue now is to ensure the dissipation limit for the max6954 is not exceeded. this can be achieved by inserting a series resistor in the supply to the max6954, ensuring that the supply decoupling capacitors are still on the max6954 side of the resistor. for example, con- sider the requirement that the minimum supply volt - age to a max6954 must be 3.0v, and the input supply range is 5v 5%. maximum supply current is 35ma + (40ma x 17) = 715ma. minimum input supply voltage is 4.75v. maximum series resistor value is (4.75v - 3.0v)/0.715a = 2.44 w . we choose 2.2 w 5%. worst- case resistor dissipation is at maximum toleranced resistance, i.e., (0.715a) 2 x (2.2 w x 1.05) = 1.18w. the maximum max6954 supply voltage is at maximum input supply voltage and minimum toleranced resis- tance, i.e., 5.25v - (0.715a x 2.2 w x 0.95) = 3.76v. low-voltage operation the max6954 works over the 2.7v to 5.5v supply range. the minimum useful supply voltage is deter- mined by the forward voltage drop of the leds at the maxim integrated 18 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
peak current iseg, plus the 0.8v headroom required by the driver output stages. the max6954 correctly regu- lates i seg with a supply voltage above this minimum voltage. if the supply drops below this minimum volt- age, the driver output stages may brown out, and be unable to regulate the current correctly. as the supply voltage drops further, the led segment drive current becomes effectively limited by the output drivers on- resistance, and the led drive current drops. the char- acteristics of each individual led in a display digit are well matched, so the result is that the display intensity dims uniformly as supply voltage drops out of regulation and beyond. computing power dissipation the upper limit for power dissipation (pd) for the max6954 is determined from the following equation: p d = (v+ x 35ma) + (v+ - v led ) (duty x i seg x n) where: v+ = supply voltage duty = duty cycle set by intensity register n = number of segments driven (worst case is 17) v led = led forward voltage at i seg i seg = segment current set by r set p d = power dissipation, in mw if currents are in ma dissipation example: i seg = 30ma, n = 17, duty = 15/16, v led = 2.4v at 30ma, v+ = 3.6v p d = 3.6v (35ma) + (3.6v - 2.4v)(15/16 x 30ma x 17) = 0.700w thus, for a 36-pin ssop package (t ja = 1 / 0.0118 = +85c/w from operating ratings), the maximum allowed ambient temperature t a is given by: t j(max) = t a + (p d x t ja ) = +150c = t a + (0.700 x +85c/w) so t a = +90.5c. thus, the part can be operated safely at a maximum package temperature of +85c. power supplies the max6954 operates from a single 2.7v to 5.5v power supply. bypass the power supply to gnd with a 0.1f capacitor as close to the device as possible. add a 47f capacitor if the max6954 is not close to the boards input bulk decoupling capacitor. terminating the serial interface the max6954 uses fixed voltage thresholds of 0.6v and 1.8v for the 4-wire interface inputs. these fixed thresholds allow the max6954 to be controlled by a host operating from a lower supply voltage than the max6954; for example, 2.5v. the fixed thresholds also reduce the logic input noise margin when operating the max6954 from a higher supply voltage, such as 5v. at higher supply voltages, it may be necessary to fit termi- nation components to the clk, din, and cs inputs to avoid signal reflections that the max6954 could respond to as multiple transitions. suitable termination components can be either a 33pf capacitor or 4.7k? resistor fitted from each of the clk, din, and cs inputs to gnd. maxim integrated 19 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 8. 14-segment display font map table 7. 16-segment display font map x000 x010 x011 x100 x101 x110 x111 x001 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 . msb lsb x000 x010 x011 x100 x101 x110 x111 x001 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 msb lsb maxim integrated 20 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 10. segment decoding for 7-segment displays table 9. digit plane data register format mode address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 segment line 0x20 to 0x2f 0x40 to 0x4f 0x60 to 0x6f dp a b c d e f g mode address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 14-segment or 16-segment mode, writing digit data to use font map data with decimal place unlit 0x20 to 0x2f 0x40 to 0x4f 0x60 to 0x6f 0 bits d6 to d0 select font characters 0 to 127 14-segment or 16-segment mode, writing digit data to use font map data with decimal place lit 0x20 to 0x2f 0x40 to 0x4f 0x60 to 0x6f 1 bits d6 to d0 select font characters 0 to 127 7-segment decode mode, dp unlit 0x20 to 0x2f 0x40 to 0x4f 0x60 to 0x6f 0 0 0 0 d3 to d0 7-segment decode mode, dp lit 0x20 to 0x2f 0x40 to 0x4f 0x60 to 0x6f 1 0 0 0 d3 to d0 7-segment no-decode mode 0x20 to 0x2f 0x40 to 0x4f 0x60 to 0x6f direct control of 8 segments maxim integrated 21 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 12. digit-type register *the decimal point is set by bit d7 = 1. table 11. 7-segment segment mapping decoder for hexadecimal font digit-type register address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 output drive line 0x0c cc7 cc6 cc5 cc4 cc3 cc2 cc1 cc0 slot identification slot 4 slot 3 slot 2 slot 1 7-segment character register data on segments = 1 d7* d6, d5, d4 d3 d2 d1 d0 dp* a b c d e f g 0 x 0 0 0 0 1 1 1 1 1 1 0 1 x 0 0 0 1 0 1 1 0 0 0 0 2 x 0 0 1 0 1 1 0 1 1 0 1 3 x 0 0 1 1 1 1 1 1 0 0 1 4 x 0 1 0 0 0 1 1 0 0 1 1 5 x 0 1 0 1 1 0 1 1 0 1 1 6 x 0 1 1 0 1 0 1 1 1 1 1 7 x 0 1 1 1 1 1 1 0 0 0 0 8 x 1 0 0 0 1 1 1 1 1 1 1 9 x 1 0 0 1 1 1 1 1 0 1 1 a x 1 0 1 0 1 1 1 0 1 1 1 b x 1 0 1 1 0 0 1 1 1 1 1 c x 1 1 0 0 1 0 0 1 1 1 0 d x 1 1 0 1 0 1 1 1 1 0 1 e x 1 1 1 0 1 0 0 1 1 1 1 f x 1 1 1 1 1 0 0 0 1 1 1 maxim integrated 22 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 14. decode-mode register examples table 13. example configurations for display digit combinations decode mode address code (hex) register data hex code d7 d6 d5 d4 d3 d2 d1 d0 no decode for digit pairs 7 to 0. 0x01 0 0 0 0 0 0 0 0 0x00 hexadecimal decode for digit pair 0, no decode for digit pairs 7 to 1. 0x01 0 0 0 0 0 0 0 1 0x01 hexadecimal decode for digit pairs 2 to 0, no decode for digit pairs 7 to 3. 0x01 0 0 0 0 0 1 1 1 0x07 hexadecimal decode for digit pairs 7 to 0. 0x01 1 1 1 1 1 1 1 1 0xff digit-type register setting address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 digits 7 to 0 are 16-segment or 7-segment digits. 0x0c 0 0 0 0 0 0 0 0 digit 0 is a 14-segment digit, digits 7 to 1 are 16-segment or 7-segment digits. 0x0c 0 0 0 0 0 0 0 1 digits 2 to 0 are 14-segment digits, digits 7 to 3 are 16-segment or 7-segment digits. 0x0c 0 0 0 0 0 1 1 1 digits 7 to 0 are 14-segment digits. 0x0c 1 1 1 1 1 1 1 1 maxim integrated 23 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 15. initial power-up register status register power-up condition address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 decode mode decode mode enabled 0x01 1 1 1 1 1 1 1 1 global intensity 1/16 (min on) 0x02 x x x x 0 0 0 0 scan limit display 8 digits: 0, 1, 2, 3, 4, 5, 6, 7 0x03 x x x x x 1 1 1 control register shutdown enabled, blink speed is slow, blink disabled 0x04 0 0 x x 0 0 0 0 gpio data outputs are low 0x05 x x x 0 0 0 0 0 port configuration no key scanning, p0 to p4 are all inputs 0x06 0 0 0 1 1 1 1 1 display test normal operation 0x07 x x x x x x x 0 key_a mask none of the keys cause interrupt 0x08 0 0 0 0 0 0 0 0 key_b mask none of the keys cause interrupt 0x09 0 0 0 0 0 0 0 0 key_c mask none of the keys cause interrupt 0x0a 0 0 0 0 0 0 0 0 key_d mask none of the keys cause interrupt 0x0b 0 0 0 0 0 0 0 0 digit type all are 16 segment or 7 segment 0x0c 0 0 0 0 0 0 0 0 intensity10 1/16 (min on) 0x10 0 0 0 0 0 0 0 0 intensity32 1/16 (min on) 0x11 0 0 0 0 0 0 0 0 intensity54 1/16 (min on) 0x12 0 0 0 0 0 0 0 0 intensity76 1/16 (min on) 0x13 0 0 0 0 0 0 0 0 intensity10a 1/16 (min on) 0x14 0 0 0 0 0 0 0 0 intensity32a 1/16 (min on) 0x15 0 0 0 0 0 0 0 0 intensity54a 1/16 (min on) 0x16 0 0 0 0 0 0 0 0 intensity76a 1/16 (min on) 0x17 0 0 0 0 0 0 0 0 digit 0 blank digit, both planes 0x60 0 0 1 0 0 0 0 0 digit 1 blank digit, both planes 0x61 0 0 1 0 0 0 0 0 digit 2 blank digit, both planes 0x62 0 0 1 0 0 0 0 0 digit 3 blank digit, both planes 0x63 0 0 1 0 0 0 0 0 digit 4 blank digit, both planes 0x64 0 0 1 0 0 0 0 0 digit 5 blank digit, both planes 0x65 0 0 1 0 0 0 0 0 digit 6 blank digit, both planes 0x66 0 0 1 0 0 0 0 0 digit 7 blank digit, both planes 0x67 0 0 1 0 0 0 0 0 digit 0a blank digit, both planes 0x68 0 0 0 0 0 0 0 0 digit 1a blank digit, both planes 0x69 0 0 0 0 0 0 0 0 digit 2a blank digit, both planes 0x6a 0 0 0 0 0 0 0 0 digit 3a blank digit, both planes 0x6b 0 0 0 0 0 0 0 0 digit 4a blank digit, both planes 0x6c 0 0 0 0 0 0 0 0 digit 5a blank digit, both planes 0x6d 0 0 0 0 0 0 0 0 digit 6a blank digit, both planes 0x6e 0 0 0 0 0 0 0 0 digit 7a blank digit, both planes 0x6f 0 0 0 0 0 0 0 0 key_a debounced no key presses have been detected 0x88 0 0 0 0 0 0 0 0 key_b debounced no key presses have been detected 0x89 0 0 0 0 0 0 0 0 key_c debounced no key presses have been detected 0x8a 0 0 0 0 0 0 0 0 key_d debounced no key presses have been detected 0x8b 0 0 0 0 0 0 0 0 key_a pressed keys are not pressed 0x8c 0 0 0 0 0 0 0 0 key_b pressed keys are not pressed 0x8d 0 0 0 0 0 0 0 0 key_c pressed keys are not pressed 0x8e 0 0 0 0 0 0 0 0 key_d pressed keys are not pressed 0x8f 0 0 0 0 0 0 0 0 maxim integrated 24 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 22. global clear digit data (r data bit d5) format table 21. global blink timing synchronization (t data bit d4) format table 20. digit register mapping with blink globally enabled table 19. global blink enable/disable (e data bit d3) format table 18. blink rate selection (b data bit d2) format table 17. shutdown control (s data bit do) format table 16. configuration register format mode register data d7 d6 d5 d4 d3 d2 d1 d0 digit data for both planes p0 and p1 are unaffected. p i 0 t e b x s digit data for both planes p0 and p1 are cleared on the rising edge of cs . p i 1 t e b x s mode register data d7 d6 d5 d4 d3 d2 d1 d0 blink timing counters are unaffected. p i r 0 e b x s blink timing counters are reset on the rising edge of cs . p i r 1 e b x s segments bit setting in plane p1 segments bit setting in plane p0 segment behavior 0 0 segment off. 0 1 segment on only during the 1st half of each blink period. 1 0 segment on only during the 2nd half of each blink period. 1 1 segment on. mode register data d7 d6 d5 d4 d3 d2 d1 d0 blink function is disabled. p i r t 0 b x s blink function is enabled. p i r t 1 b x s mode register data d7 d6 d5 d4 d3 d2 d1 d0 slow blinking. segments blink on for 1s, off for 1s with f osc = 4mhz. p i r t e 0 x s fast blinking. segments blink on for 0.5s, off for 0.5s with f osc = 4mhz. p i r t e 1 x s mode register data d7 d6 d5 d4 d3 d2 d1 d0 shutdown p i r t e b x 0 normal operation p i r t e b x 1 mode register data d7 d6 d5 d4 d3 d2 d1 d0 configuration register p i r t e b x s maxim integrated 25 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 26. global intensity register format table 25. scan-limit register format table 24. blink phase readback (p data bit d7) format table 23. global intensity (i data bit d6) format duty cycle typical segment current ( m a) address code (hex) register data hex code d7 d6 d5 d4 d3 d2 d1 d0 1/16 (min on) 2.5 0x02 x x x x 0 0 0 0 0xx0 2/16 5 0x02 x x x x 0 0 0 1 0xx1 3/16 7.5 0x02 x x x x 0 0 1 0 0xx2 4/16 10 0x02 x x x x 0 0 1 1 0xx3 5/16 12.5 0x02 x x x x 0 1 0 0 0xx4 6/16 15 0x02 x x x x 0 1 0 1 0xx5 7/16 17.5 0x02 x x x x 0 1 1 0 0xx6 8/16 20 0x02 x x x x 0 1 1 1 0xx7 9/16 22.5 0x02 x x x x 1 0 0 0 0xx8 10/16 25 0x02 x x x x 1 0 0 1 0xx9 11/16 27.5 0x02 x x x x 1 0 1 0 0xxa 12/16 30 0x02 x x x x 1 0 1 1 0xxb 13/16 32.5 0x02 x x x x 1 1 0 0 0xxc 14/16 35 0x02 x x x x 1 1 0 1 0xxd 15/16 37.5 0x02 x x x x 1 1 1 0 0xxe 15/16 (max on) 37.5 0x02 x x x x 1 1 1 1 0xxf scan limit address code (hex) register data hex code d7 d6 d5 d4 d3 d2 d1 d0 display digit 0 only 0x03 x x x x x 0 0 0 0x00 display digits 0 and 1 0x03 x x x x x 0 0 1 0x01 display digits 0 1 2 0x03 x x x x x 0 1 0 0x02 display digits 0 1 2 3 0x03 x x x x x 0 1 1 0x03 display digits 0 1 2 3 4 0x03 x x x x x 1 0 0 0x04 display digits 0 1 2 3 4 5 0x03 x x x x x 1 0 1 0x05 display digits 0 1 2 3 4 5 6 0x03 x x x x x 1 1 0 0x06 display digits 0 1 2 3 4 5 6 7 0x03 x x x x x 1 1 1 0x07 mode register data d7 d6 d5 d4 d3 d2 d1 d0 p1 blink phase 0 i r t e b x s p0 blink phase 1 i r t e b x s mode register data d7 d6 d5 d4 d3 d2 d1 d0 intensity for all digits is controlled by one setting in the global intensity register. p 0 r t e b x s intensity for digits is controlled by the individual settings in the intensity10 and intensity76 registers. p 1 r t e b x s maxim integrated 26 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 28. even individual segment intensity format table 27. individual segment intensity registers duty cycle typical segment current ( m a) address code (hex) register data hex code d7 d6 d5 d4 d3 d2 d1 d0 1/16 (min on) 2.5 0x10 to 0x17 see table 29. 0 0 0 0 0xx0 2/16 5 0x10 to 0x17 0 0 0 1 0xx1 3/16 7.5 0x10 to 0x17 0 0 1 0 0xx2 4/16 10 0x10 to 0x17 0 0 1 1 0xx3 5/16 12.5 0x10 to 0x17 0 1 0 0 0xx4 6/16 15 0x10 to 0x17 0 1 0 1 0xx5 7/16 17.5 0x10 to 0x17 0 1 1 0 0xx6 8/16 20 0x10 to 0x17 0 1 1 1 0xx7 9/16 22.5 0x10 to 0x17 1 0 0 0 0xx8 10/16 25 0x10 to 0x17 1 0 0 1 0xx9 11/16 27.5 0x10 to 0x17 1 0 1 0 0xxa 12/16 30 0x10 to 0x17 1 0 1 1 0xxb 13/16 32.5 0x10 to 0x17 1 1 0 0 0xxc 14/16 35 0x10 to 0x17 1 1 0 1 0xxd 15/16 37.5 0x10 to 0x17 1 1 1 0 0xxe 15/16 (max on) 37.5 0x10 to 0x17 1 1 1 1 0xxf register function address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 intensity10 register 0x10 digit 1 digit 0 intensity32 register 0x11 digit 3 digit 2 intensity54 register 0x12 digit 5 digit 4 intensity76 register 0x13 digit 7 digit 6 intensity10a register 0x14 digit 1a (7 segment only) digit 0a (7 segment only) intensity32a register 0x15 digit 3a (7 segment only) digit 2a (7 segment only) intensity54a register 0x16 digit 5a (7 segment only) digit 4a (7 segment only) intensity76a register 0x17 digit 7a (7 segment only) digit 6a (7 segment only) maxim integrated 27 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 31. port scanning function allocation table 30. gpio data register table 29. odd individual segment intensity format keys scanned ports available p0 p1 p2 p3 p4 none 5 pins gpio gpio gpio gpio gpio 1 to 8 3 pins key_a gpio gpio gpio irq 9 to 16 2 pins key_a key_b gpio gpio irq 17 to 24 1 pin key_a key_b key_c gpio irq 25 to 36 none key_a key_b key_c key_d irq mode address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 write gpio data 0x05 x x x p4 p3 p2 p1 p0 read gpio data 0x85 0 0 0 p4 or irq status p3 p2 p1 p0 duty cycle typical segment current ( m a) address code (hex) register data hex code d7 d6 d5 d4 d3 d2 d1 d0 1/16 (min on) 2.5 0x10 to 0x17 0 0 0 0 see table 28. 0x0x 2/16 5 0x10 to 0x17 0 0 0 1 0x1x 3/16 7.5 0x10 to 0x17 0 0 1 0 0x2x 4/16 10 0x10 to 0x17 0 0 1 1 0x3x 5/16 12.5 0x10 to 0x17 0 1 0 0 0x4x 6/16 15 0x10 to 0x17 0 1 0 1 0x5x 7/16 17.5 0x10 to 0x17 0 1 1 0 0x6x 8/16 20 0x10 to 0x17 0 1 1 1 0x7x 9/16 22.5 0x10 to 0x17 1 0 0 0 0x8x 10/16 25 0x10 to 0x17 1 0 0 1 0x9x 11/16 27.5 0x10 to 0x17 1 0 1 0 0xax 12/16 30 0x10 to 0x17 1 0 1 1 0xbx 13/16 32.5 0x10 to 0x17 1 1 0 0 0xcx 14/16 35 0x10 to 0x17 1 1 0 1 0xdx 15/16 37.5 0x10 to 0x17 1 1 1 0 0xex 15/16 (max on) 37.5 0x10 to 0x17 1 1 1 1 0xfx maxim integrated 28 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 33. key mask register format table 32. port configuration register format key mask register address code (hex register data with appropriate switch named below d7 d6 d5 d4 d3 d2 d1 d0 key_a mask register 0x08 sw_a7 sw_a6 sw_a5 sw_a4 sw_a3 sw_a2 sw_a1 sw_a0 key_b mask register 0x09 sw_b7 sw_b6 sw_b5 sw_b4 sw_b3 sw_b2 sw_b1 sw_b0 key_c mask register 0x0a sw_c7 sw_c6 sw_c5 sw_c4 sw_c3 sw_c2 sw_c1 sw_c0 key_d mask register 0x0b sw_ d7 sw_d6 sw_d5 sw_d4 sw_d3 sw_d2 sw_d1 sw_d0 mode address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 gpio configuration register 0x06 set number of keys scanned set port direction for ports p0 to p4: 0 = output, 1 = input port allocation options 0 keys scanned 0x06 0 0 0 p4 p3 p2 p1 p0 8 keys scanned 0x06 0 0 1 irq p3 p2 p1 key_a 16 keys scanned 0x06 0 1 0 irq p3 p2 key_b key_a 24 keys scanned 0x06 0 1 1 irq p3 key_c key_b key_a 32 keys scanned 0x06 1 x x irq key_d key_c key_b key_a example port configuration settings no keys scanned, p4 and p2 are outputs, others are inputs 0x06 0 0 0 0 1 0 1 1 8 keys scanned, p3 and p1 are outputs, p2 is an input 0x06 0 0 1 x 0 1 0 x 32 keys scanned, no gpio ports 0x06 1 x x x x x x x maxim integrated 29 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
table 36. display test register table 35. key pressed register format table 34. key debounced register format mode address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 normal operation 0x07 x x x x x x x 0 display test 0x07 x x x x x x x 1 key pressed register address code (hex register data d7 d6 d5 d4 d3 d2 d1 d0 key_a pressed register 0x8c sw_a7 sw_a6 sw_a5 sw_a4 sw_a3 sw_a2 sw_a1 sw_a0 key_b pressed register 0x8d sw_b7 sw_b6 sw_b5 sw_b4 sw_b3 sw_b2 sw_b1 sw_b0 key_c pressed register 0x8e sw_c7 sw_c6 sw_c5 sw_c4 sw_c3 sw_c2 sw_c1 sw_c0 key_d pressed register 0x8f sw_d7 sw_d6 sw_d5 sw_d4 sw_d3 sw_d2 sw_d1 sw_d0 key debounced register address code (hex) register data d7 d6 d5 d4 d3 d2 d1 d0 key_a debounced register 0x88 sw_a7 sw_a6 sw_a5 sw_a4 sw_a3 sw_a2 sw_a1 sw_a0 key_b debounced register 0x89 sw_b7 sw_b6 sw_b5 sw_b4 sw_b3 sw_b2 sw_b1 sw_b0 key_c debounced register 0x8a sw_c7 sw_c6 sw_c5 sw_c4 sw_c3 sw_c2 sw_c1 sw_c0 key_d debounced register 0x8b sw_d7 sw_d6 sw_d5 sw_d4 sw_d3 sw_d2 sw_d1 sw_d0 maxim integrated 30 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
*7-segment digits can be replaced by directly controlled discrete leds according to settings in decode mode register (table 11). **the highlighted row is used in typical operating circuit 1 for display digits 0 and 1. table 37. slot 1 configuration configuration choice common-cathode drive: digit type cc0: 16-seg monocolor cc1: 16-seg monocolor cc0 and cc1: (2) 7-seg bicolor or (4) 7-seg monocolor or (1) 7-seg bicolor and (2) 7-seg monocolor* cc0 and cc1: (1)16-seg bicolor cc0: 16-seg monocolor cc0: (2) 7-seg monocolor* or 7-seg bicolor cc1: 14-seg monocolor cc0: 14-seg monocolor cc1: 16-seg monocolor cc1: (2) 7-seg monocolor* or 7-seg bicolor cc0 and cc1: (2) 14-seg monocolor or 14-seg bicolor 00 cc0 cc0 cc0 cc0 cc0 cc0 cc0 01 cc1 cc1 cc1 cc1 cc1 cc1 cc1 02 a1 a1 1a a1 a1 1a a a a1 1a a 03 a2 a2 a2 a2 a2 04 b b 1b b b 1b b b b 1b b 05 c c 1c c c 1c c c c 1c c 06 d1 d1 1d d1 d1 1d d d d1 1d d 07 d2 d2 1dp d2 d2 1dp d2 1dp 08 e e 1e e e 1e e e e 1e e 09 f f 1f f f 1f f f f 1f f 010 g1 g1 1g g1 g1 1g g1 g1 g1 1g g1 011 g2 g2 2a g2 g2 2a g2 g2 g2 2a g2 012 h h 2b h h 2b h h h 2b h 013 i i 2c i i 2c i i i 2c i 014 j j 2d j j 2d j j j 2d j 015 k k 2e k k 2e k k k 2e k 016 l l 2f l l 2f l l l 2f l 017 m m 2g m m 2g m m m 2g m 018 dp dp 2dp dp dp 2dp dp dp dp 2dp dp address code (hex) 0x0c register data d7 see table 40. d6 d5 see table 39. d4 d3 see table 38. d2 d1 0 1 0 1 d0 0 0 1 1 maxim integrated 31 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
*7-segment digits can be replaced by directly controlled discrete leds according to settings in decode mode register (table 11). **the highlighted row is used in typical operating circuit 1 for display digits 2 and 3. table 38. slot 2 configuration configuration choice common-cathode drive: digit type cc2: 16-seg monocolor cc3: 16-seg monocolor cc2 and cc3: (2) 7-seg bicolor or (4) 7-seg monocolor or (1) 7-seg bicolor and (2) 7-seg monocolor* cc2 and cc3: (1)16-seg bicolor cc2: 16-seg monocolor cc2: (2) 7-seg monocolor* or 7-seg bicolor cc3: 14-seg monocolor cc2: 14-seg monocolor cc3: 16-seg monocolor cc3: (2) 7-seg monocolor* or 7-seg bicolor cc2 and cc3: (2) 14-seg monocolor or 14-seg bicolor 00 a1 a1 1a a1 a1 1a a a a1 1a a 01 a2 a2 a2 a2 a2 02 cc2 cc2 cc2 cc2 cc2 cc2 cc2 03 cc3 cc3 cc3 cc3 cc3 cc3 cc3 04 b b 1b b b 1b b b b 1b b 05 c c 1c c c 1c c c c 1c c 06 d1 d1 1d d1 d1 1d d d d1 1d d 07 d2 d2 1dp d2 d2 1dp d2 1dp 08 e e 1e e e 1e e e e 1e e 09 f f 1f f f 1f f f f 1f f 010 g1 g1 1g g1 g1 1g g1 g1 g1 1g g1 011 g2 g2 2a g2 g2 2a g2 g2 g2 2a g2 012 h h 2b h h 2b h h h 2b h 013 i i 2c i i 2c i i i 2c i 014 j j 2d j j 2d j j j 2d j 015 k k 2e k k 2e k k k 2e k 016 l l 2f l l 2f l l l 2f l 017 m m 2g m m 2g m m m 2g m 018 dp dp 2dp dp dp 2dp dp dp dp 2dp dp address code (hex) 0x0c register data d7 see table 40. d6 d5 see table 39. d4 d3 0 1 0 1 d2 0 0 1 1 d1 see table 37. d0 maxim integrated 32 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
*7-segment digits can be replaced by directly controlled discrete leds according to settings in decode mode register (table 11). **the highlighted row is used in typical operating circuit 1 for display digits 4 and 5. table 39. slot 3 configuration configuration choice common-cathode drive: digit type cc4: 16-seg monocolor cc5: 16-seg monocolor cc4 and cc5: (2) 7-seg bicolor or (4) 7-seg monocolor or (1) 7-seg bicolor and (2) 7-seg monocolor* cc4 and cc5: (1)16-seg bicolor cc4: 16-seg monocolor cc4: (2) 7-seg monocolor* or 7-seg bicolor cc5: 14-seg monocolor cc4: 14-seg monocolor cc5: 16-seg monocolor cc5: (2) 7-seg monocolor* or 7-seg bicolor cc4 and cc5: (2) 14-seg monocolor or 14-seg bicolor 00 a1 a1 1a a1 a1 1a a a a1 1a a 01 a2 a2 a2 a2 a2 02 b b 1b b b 1b b b b 1b b 03 c c 1c c c 1c c c c 1c c 04 cc4 cc4 cc4 cc4 cc4 cc4 cc4 05 cc5 cc5 cc5 cc5 cc5 cc5 cc5 06 d1 d1 1d d1 d1 1d d d d1 1d d 07 d2 d2 1dp d2 d2 1dp d2 1dp 08 e e 1e e e 1e e e e 1e e 09 f f 1f f f 1f f f f 1f f 010 g1 g1 1g g1 g1 1g g1 g1 g1 1g g1 011 g2 g2 2a g2 g2 2a g2 g2 g2 2a g2 012 h h 2b h h 2b h h h 2b h 013 i i 2c i i 2c i i i 2c i 014 j j 2d j j 2d j j j 2d j 015 k k 2e k k 2e k k k 2e k 016 l l 2f l l 2f l l l 2f l 017 m m 2g m m 2g m m m 2g m 018 dp dp 2dp dp dp 2dp dp dp dp 2dp dp address code (hex) 0x0c register data d7 see table 40. d6 d5 0 1 0 1 d4 0 0 1 1 d3 see table 38. d2 d1 see table 37. d0 maxim integrated 33 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
*7-segment digits can be replaced by directly controlled discrete leds according to settings in the decode mode register (table 11). **the highlighted row is used in typical operating circuit 1 for display digits 6 and 7. table 40. slot 4 configuration configuration choice common-cathode drive: digit type cc6: 16-seg monocolor cc7: 16-seg monocolor cc6 and cc7: (2) 7-seg bicolor or (4) 7-seg monocolor or (1) 7-seg bicolor and (2) 7-seg monocolor* cc6 and cc7: (1)16-seg bicolor cc6: 16-seg monocolor cc6: (2) 7-seg monocolor* or 7-seg bicolor cc7: 14-seg monocolor cc6: 14-seg monocolor cc7: 16-seg monocolor cc7: (2) 7-seg monocolor* or 7-seg bicolor cc6 and cc7: (2) 14-seg monocolor or 14-seg bicolor 00 a1 a1 1a a1 a1 1a a a a1 1a a 01 a2 a2 a2 a2 a2 02 b b 1b b b 1b b b b 1b b 03 c c 1c c c 1c c c c 1c c 04 d1 d1 1d d1 d1 1d d d d1 1d d 05 d2 d2 1dp d2 d2 1dp d2 1dp 06 cc6 cc6 cc6 cc6 cc6 cc6 cc6 07 cc7 cc7 cc7 cc7 cc7 cc7 cc7 08 e e 1e e e 1e e e e 1e e 09 f f 1f f f 1f f f f 1f f 010 g1 g1 1g g1 g1 1g g1 g1 g1 1g g1 011 g2 g2 2a g2 g2 2a g2 g2 g2 2a g2 012 h h 2b h h 2b h h h 2b h 013 i i 2c i i 2c i i i 2c i 014 j j 2d j j 2d j j j 2d j 015 k k 2e k k 2e k k k 2e k 016 l l 2f l l 2f l l l 2f l 017 m m 2g m m 2g m m m 2g m 018 dp dp 2dp dp dp 2dp dp dp dp 2dp dp address code (hex) 0x0c register data d7 0 1 0 1 d6 0 0 1 1 d5 see table 39. d4 d3 see table 38. d2 d1 see table 37. d0 maxim integrated 34 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
typical operating circuits f a rcc dp g gcc b c e d digit 0b (red), digit 1b (green) 7-segment bicolor led o16 o17 o18 o0 o1 o11 o12 o13 o14 o0 o2 o3 o4 o15 f a h g2 g1 i b c e d digits 2 and 3 14-segment bicolor digit 6 4 x 4 matrix of discrete monocolor leds o8 o9 o10 o11 o12 o0 o4 o5 o6 m rcc dp ccc j l k o16 o17 o18 o2 o3 o13 o14 o15 f a cc1 dp g cc0 b c e d digits 0a and 1a 7-segment monocolor o9 o10 o7 o1 o0 o2 o4 o5 o6 o8 d2 a1 g1 f e g2 a2 b d1 c digit 5 16-segment monocolor o6 o7 o8 o9 o10 o0 o1 o2 o3 k m l dp h j i o14 o15 o16 o17 o18 cc o5 o11 o12 o13 d2 a1 g1 f e g2 a2 b d1 c digit 4 16-segment monocolor o6 o7 o8 o9 o10 o0 o1 o2 o3 k m l dp h j i o14 o15 o16 o17 o18 cc o4 o11 o12 o13 3.3v 100nf 47f o0 o1 o2 o3 o4 o5 o6 o7 o8 o9 o10 o11 o12 o13 o14 o15 o16 o17 o18 p0 p1 p2 p3 p4 iset 56k? osc_out osc v+ v+ gnd gnd dout v+ gnd din clk cs blink o5 o8 o9 o10 o11 o12 o13 o14 o15 o16 o17 o18 o6 22pf o0 o2 o3 o4 digit 7 4 x 4 matrix of discrete monocolor leds o5 o8 o9 o10 o11 o12 o13 o14 o15 o16 o17 o18 o7 max6954 maxim integrated 35 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
typical operating circuits (continued) d2 a g1 f e g2 a2 b d1 c digit 0 o6 o7 o8 o9 o10 o2 o3 o4 o5 k m l dp h j i o14 o15 o16 o17 o18 cc o0 o11 o12 o13 d2 a g1 f e g2 a2 b d1 c digit 2 o6 o7 o8 o9 o10 o0 o1 o4 o5 k m l dp h j i o14 o15 o16 o17 o18 cc o2 o11 o12 o13 3.3v 100nf 47f o0 o1 o2 o3 o4 o5 o6 o7 o8 o9 o10 o11 o12 o13 o14 o15 o16 o17 o18 p0 p1 p2 p3 p4 iset osc_out osc v+ v+ gnd gnd dout v+ gnd din clk cs blink d2 a g1 f e g2 a2 b d1 c digit 1 o6 o7 o8 o9 o10 o2 o3 o4 o5 k m l dp h j i o14 o15 o16 o17 o18 cc o1 o11 o12 o13 d2 a g1 f e g2 a2 b d1 c digit 3 o6 o7 o8 o9 o10 o0 o1 o4 o5 k m l dp h j i o14 o15 o16 o17 o18 cc o3 o11 o12 o13 d2 a g1 f e g2 a2 b d1 c digit 6 o4 o5 o8 o9 o10 o0 o1 o2 o3 k m l dp h j i o14 o15 o16 o17 o18 cc o6 o11 o12 o13 d2 a g1 f e g2 a2 b d1 c digit 7 o4 o5 o8 o9 o10 o0 o1 o2 o3 k m l dp h j i o14 o15 o16 o17 o18 cc o7 o11 o12 o13 d2 a g1 f e g2 a2 b d1 c digit 4 o6 o6 o8 o9 o10 o0 o1 o2 o3 k m l dp h j i o14 o15 o16 o17 o18 cc o4 o11 o12 o13 d2 a g1 f e g2 a2 b d1 c digit 5 o6 o7 o8 o9 o10 o0 o1 o2 o3 k m l dp h j i o14 o15 o16 o17 o18 cc o5 o11 o12 o13 max6954 56k? 22pf maxim integrated 36 www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
pin confgurations 40 n.c. v+ osc v+ 39 38 37 36 35 34 33 32 31 1 2 3 4 5 6 7 8 9 10 n.c. gnd gnd iset gnd top view max6954apl 30 29 28 27 26 25 24 23 22 21 11 12 13 14 15 16 17 18 19 pdip 20 ssop max6954aax 1 2 3 4 5 6 7 8 9 10 11 12 13 14 o7 o6 o5 o4 o3 o2 o1 o0 din clk dout cs p1 p0 15 16 17 18 gnd iset gnd o8 36 35 34 33 32 31 30 29 28 27 26 25 24 23 p4 p3 p2 osc_out blink o18 o10 o17 o16 o15 o14 o13 o12 o11 22 21 20 19 v+ o9 p4 p3 p2 osc_out blink o18 o10 o17 o16 o15 o14 o13 o12 o11 o9 osc v+ o7 o6 o5 o4 o3 o2 o1 o0 din clk dout cs p1 p0 o8 v+ o18 o17 o15 o14 o11 o10 o9 ep* o13 o12 o16 o1 o2 o3 o4 o5 o6 o7 o8 o0 din 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 gnd v+ osc v+ n.c. iset gnd gnd n.c. dout cs p1 p0 p4/irq p3 p2 osc_out blink clk tqfn-ep + max6954 v+ *ep = exposed pad. connect ep to gnd. maxim integrated 37 chip information process: bicmos www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
package type package code document no. land pattern no. 36 ssop a36-2 21-0040 90-0098 40 pdip p40-2 21-0044 40 tqfn-ep t4066+5 21-0141 90-0055 maxim integrated 38 package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. www.maximintegrated.com max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan
revision number revision date description pages changed 3 6/08 added tqfn package option 1, 2, 6, 37 4 3/09 corrected errors in tables 37C40 31C34 5 7/14 removed automotive reference from data sheet 1 ? 2014 maxim integrated products, inc. 39 revision history maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and specifcations without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max6954 4-wire interfaced, 2.7v to 5.5v led display driver with i/o expander and key scan for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com.

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