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| 1 TC7211AM BUS COMPATIBLE 4-DIGIT CMOS DECODER/DRIVER FEATURES s s s s s 4-Digit Non-Multiplexed 7-Segment LCD Outputs With Backplane Driver Input and Digit Select Data Latches RC Oscillator On-Chip Generates Backplane Drive Signal Eliminates DC Bias Which Degrades LCD Life Backplane Input/Output Pin Permits Synchronization of Cascaded Slave Device to a Master Backplane Signal Binary and BCD Inputs Decoded to Code B (0 to 9, --, E, H, L, P, Blank) Pin Compatible and Functionally Equivalent to ICM7211AM 2 3 4 5 6 7 GENERAL DESCRIPTION The TC7211AM (LCD Decoder/driver) is a CMOS direct drive, 4-digit, 7-segment display decoder and driver. The TC7211AM drives conventional LCDs. An RC oscillator, divider chain, backplane driver, and 28-segment outputs are provided on a single CMOS chip. The segment drivers supply square waves of the same frequency as the backplane, but in-phase for an OFF segment and out-ofphase for an ON segment. The net DC voltage applied between driver segment and backplane is near zero maximizing display lifetime. The four bit binary input is decoded into the seven segment alphanumeric code known as "Code B". The "Code B" output format results in a 0 to 9,--, E, H, L, P or blank display. True BCD or binary inputs will be correctly decoded to the seven segment display format. s s PIN CONFIGURATIONS ORDERING INFORMATION V+ E1 G1 F1 BP A2 B2 C2 D2 1 2 3 4 5 6 7 8 9 40 D1 39 C1 Part No. TC7211AMIPL Driver Type LCD Input Package Code 40-Pin Code B Plastic DIP Output Config. Data and Digit Select Latches 38 B1 37 A1 36 OSCILLATOR 35 GND 34 CHIP SELECT 2 (CS2) 33 CHIP SELECT 1 (CS1) 32 DIGIT SELECT 2 (DS2 31 DIGIT SELECT 1 (DS1 TC7211AM (LCD) 30 B3 29 B2 28 B1 27 B0 26 F4 25 G4 24 E4 23 D4 22 C4 21 B4 DATA INPUTS E2 10 G2 11 F2 12 A3 13 B3 14 C3 15 D3 16 E3 17 G3 18 F3 19 A4 20 8 TC7211AM-4 11/14/96 TELCOM SEMICONDUCTOR, INC. 6-7 BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM FUNCTIONAL BLOCK DIAGRAM TC7211AM V+ D4 SEGMENT OUTPUTS 1 g 7 WIDE DRIVER 7 WIDE LATCH ENABLE PROGRAMMABLE 4-TO-7 DECODER 27 28 29 30 B0 B1 B2 B3 a D3 SEGMENT OUTPUTS D2 SEGMENT OUTPUTS D1 SEGMENT OUTPUTS GND 35 7 WIDE DRIVER 7 WIDE LATCH ENABLE PROGRAMMABLE 4-TO-7 DECODER 7 WIDE DRIVER 7 WIDE LATCH ENABLE PROGRAMMABLE 4-TO-7 DECODER 7 WIDE DRIVER 7 WIDE LATCH ENABLE PROGRAMMABLE 4-TO-7 DECODER DATA INPUTS 4-BIT LATCH ENABLE DIGIT SELECT INPUTS 31 DS1 32 DS2 2-BIT LATCH 2-TO-4 DECODER ENABLE BACK- PLANE DRIVER ENABLE BACKPLANE (INPUT/OUTPUT) ENABLE CS1 CS2 33 34 ONE SHOT OSCILLATOR INPUT 36 ENABLE DETECTOR OSCILLATOR (16 kHz FREERUNNING) /128 6-8 TELCOM SEMICONDUCTOR, INC. BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM ABSOLUTE MAXIMUM RATINGS* Supply Voltage ........................................................ +6.5V Input Voltage, Any Terminal (Note 2) .................................... V+ +0.3V, GND -0.3V Power Dissipation TA 70C (Note 1) ................... 1.23W Operating Temperature Range ................ -20C to +85C Storage Temperature Range ................. -65C to +150C Lead Temperature (Soldering, 10 sec) ................. +300C *Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. NOTES: 1. This limit refers to that of the package and will not be realized during normal operation. 2. Due to the SCR structure inherent in the CMOS process, connecting any terminal to voltages greater than V+ or less than GND may cause destructive latch-up. For this reason, it is recommended that inputs from external sources not operating on the same power supply not be applied to the device before its supply is established, and, in multiple supply systems, the supply to the TC7211AM be turned on first. 1 2 3 4 5 6 7 TYPICAL CHARACTERISTICS: All parameters measured with V+ = 5V, TA = 25C Symbol VSUP IOP IOSCI tRFS tRFB fOSC fBP VIH VIL IILK CIN IBPLK CBPI Parameter Operating Voltage Range Operating Current Oscillator Input Current Segment Rise/Fall Time Backplane Rise/Fall Time Oscillator Frequency Backplane Frequency Logic "1" High Input Voltage Logic "0" Low Input Voltage Input Leakage Current Input Capacitance BP Input Current Leakage BP Input Capacitance Test Conditions Display Blank Pin 36 CL = 200 pF CL = 5000 pF Pin 36 Floating Pin 36 Floating Min 3 -- -- -- -- -- -- 3 -- -- -- -- -- Typ 5 10 2 0.5 1.5 16 125 -- -- 0.01 5 0.01 200 Max 6 50 10 -- -- -- -- -- 1 1 -- 1 -- Unit V A A sec sec kHz Hz V V A pF A pF Input Characteristics Pins 27-34 Pins 27-34 Measured at Pin 5 With Pin 36 at GND All Devices AC Characteristics Symbol tCSA tDS tDH tICS Parameter Chip Select Active Pulse Width Data Setup Time Data Hold Time Inter-Chip Select Time Test Conditions (Note 1) 200 100 10 2 -- -- 0 -- -- -- -- -- nsec nsec nsec sec NOTE: 1. Other chip select (CS) is either held at logic zero or both CS1 and CS2 driven together. 8 TELCOM SEMICONDUCTOR, INC. 6-9 BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM TIMING DIAGRAMS CS1 (CS2) tCSA CS2 (CS1) tICS , , , , , DATA AND DIGIT SELECT CODE tDS tDH DON'T CARE Figure 1: BUS Interface Timing Diagram OSCILLATOR FREQUENCY 128 CYCLES BACKPLANE INPUT/OUTPUT 64 CYCLES OFF SEGMENTS ON SEGMENTS 64 CYCLES Figure 2: LCD Display Waveforms 6-10 TELCOM SEMICONDUCTOR, INC. BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM INPUT DEFINITIONS In this table, V+ and GND are considered to be normal operating input logic levels. For lowest power consumption, input signals should swing over the full supply. Input B0 B1 B2 B3 OSC DS1 DS2 CS1 CS2 1 2 3 4 5 Pin No. 27 28 29 30 36 31 32 33 34 Condition = Logic "1" GND = Logic "0" V+ = Logic "1" GND = Logic "0" V+ = Logic "1" GND = Logic "0" V+ = Logic "1" GND = Logic "0" Floating or with external capacitor GND V+ = Logical One GND = Logical Zero V+ = Inactive GND = Active V+ Function Ones (Least Significant) Twos Data Input Bits Fours Eights (Most Significant) Oscillator input. Disables BP output devices, allowing segments to be synchronized to an external signal input at the BP terminal (pin 5) DS2, DS1 = 00 Selects D4 DS2, DS1 = 01 Selects D3 Digit Select Inputs DS2, DS1 = 10 Selects D2 DS2, DS1 = 11 Selects D1 When both CS1 and CS2 are LOW, the data and digit select input latches are open or enabled. On the rising of CS1 or CS2, data is latched, decoded and stored in the output drive latches. OUTPUT DEFINITIONS Output pins are defined by the alphabetical segment assignment and numerical digital assignment. Output A1 B1 C1 D1 E1 F1 G1 A2 B2 C2 D2 E2 F2 G2 Pin No. 37 38 39 40 2 4 3 6 7 8 9 10 12 11 Function A Segment Drive B C D E F G A Segment Drive B C D E F G Digit 1 (LSD) Output A3 B3 C3 D3 E3 F3 G3 A4 B4 C4 D4 E4 F4 G4 Pin No. 13 14 15 16 17 19 18 20 21 22 23 24 26 25 Function A Segment Drive B C D E F G A Segment Drive B C D E F G Digit 3 6 Digit 4 (MSD) Digit 2 DIGIT ASSIGNMENT D4 A F E D G B C D3 D2 D1 7 8 6-11 TELCOM SEMICONDUCTOR, INC. BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM TYPICAL CHARACTERISTICS Operating Supply Current vs Supply Voltage 30 25 20 LCD DEVICES DISPLAY BLANK PIN 36 OPEN TA= -20C Backplane Frequency vs Supply Voltage 180 TA = +25C 150 120 BP (Hz) COSC = 0 pF (PIN 36 OPEN) IOP (A) 15 10 5 0 TA= +25C 90 COSC = 22 pF 60 TA= +70C 30 COSC = 220 pF 0 1 2 3 4 5 V+ VOLTS 6 7 1 2 3 4 5 + VOLTS V 6 7 BASIC OPERATION The TC7211AM drives 4-digit, 7-segment LCDs. This device contains 28 individual segment drivers, a backplane driver, a self-contained oscillator, and a divider chain to generate the backplane signal. The 28 CMOS segment drivers and backplane driver contain ratioed N- and P-channel transistors for identical ON resistance. The equal resistances eliminate the DC output driver component resulting from unequal rise and fall times. This ensures maximum LCD life. The backplane output driver can be disabled by grounding the OSCILLATOR input (pin 36). The 28 output segment drivers can therefore be synchronized directly to an input signal at the backplane (BP) terminal (pin 5). Several slave devices may be cascaded to the backplane output of a master device. The backplane signal may also be derived from an external source. These features permit interfacing to single backplane LCDs with characters in multiples of four. Each slave's backplane input represents a 200pF capacitive load to the master backplane driver (comparable to one additional segment). The number of slave devices drivable by a master device is therefore set by the larger display backplane capacitive load. The master backplane output will drive the display backplane of 16 one-half-inch characters with rise and fall times under 5 sec. This represents a system with three slave devices and a fourth master device driving the backplane. 6-12 If more than four devices are slaved together, the backplane signal should be derived externally and all TC7211AM devices slaved to it. The external drive signal must drive a high capacitive load with 1sec to 2 sec rise and fall times. The backplane frequency is normally 125 Hz. At lower display ambient temperatures, the frequency may be reduced to compensate for display response time. The on-chip RC oscillator free-runs at approximately 16 kHz. A divide-by 128 circuit provides the 125 Hz backplane frequency. The oscillator frequency may be reduced by connecting an external capacitor between the oscillator terminal and V+. (See typical operating characteristics curves.) The free-running oscillator may be overridden (if desired) by an external clock. The backplane driver, however, must not be disabled during the external clock's negative or lOW portion, as this will result in a DC drive component being applied to the LCD, limiting the LCD's life. To prevent backplane driver disabling, the oscillator input should be driven from the positive supply to no less than one-fifth the supply voltage above ground. A backplane disable signal will not be sensed if the driving signal remains above ground by one-fifth the supply voltage. An alternate method for externally driving the oscillator permits the oscillator input to swing the full supply voltage range. The oscillator input signal duty cycle is skewed so the LOW TELCOM SEMICONDUCTOR, INC. BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM portion duration is less than 1 sec. The backplane disable sensing circuit will not respond to such a short signal. D8 D7 D6 D5 D4 D3 D2 D1 8-DIGIT LCD BACKPLANE 1 Table 1. Binary Codes Versus Character Displayed B3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 Binary Input B2 B1 B0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Character Displayed (Code B) 0 1 2 3 4 5 6 7 8 9 -- E H L P Blank 2 3 4 5 6 7 BACKPLANE SLAVE +5V V+ GND OSC BCD/BINARY DATA CHIP SELECT 28 SEGMENTS HIGH ORDER CS2 DS2 B3- B0 CS1 DS1 BP 44 BACKPLANE MASTER 28 +5V V+ SEGMENTS HIGH ORDER GND CS2 DS2 B3- OSC B0 CS1 DS1 BP 4 TC7211AM DIGIT SELECT Figure 3. TC7211AM Driving an 8-Digit LCD Display in Master/Slave Configuration Input Configuration and Output Codes The TC7211AM accepts a 4-bit, true binary (positive level = logic "1") input at pin 27 (LSB) through pin 30 (MSB). The binary input is decoded to the 7-segment output known as Code B. The output display format is 0 to 9, --, E, H, L, P and blank display (see Table 1). Segment assignments are shown in Figure 4. The TC7211AM will correctly decode binary and BCD true codes to a 7-segment output. The TC7211AM is designed to interface with a data bus and display data under microprocessor control. Four data inputs (pins 27-30) and two digit select input bits (pins 31 and 32) are written into input buffer latches. The rising edge of either chip select causes data to be latched, decoded and stored in the selected digit output data latch. The 2-bit digit code selects the appropriate output digit latch. The 4-bit display data word is decoded to the "Code B" 7-segment output format. For applications where bus compatibility is not required, refer to the TC7211AM (LCD) 4-digit decoder driver data sheet. This device is designed to accept multiplexed BCD/ binary input data for display under the control of four separate digit select control signals. F E D A G B C Figure 4. Segment Assignment Special Order Decoder Option The TC7211AM is mask programmed to give the 16 combinations of 7-segment output codes. For large volume orders (50K pieces minimum), custom decoder options are available. Contact TelCom Semiconductor for details. 8 TELCOM SEMICONDUCTOR, INC. 6-13 |
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