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da6502.008 29 november 2012 1 (20) MAS6502 piezoresistive sensor signal interface ic ? optimized for piezoresistive pressure sensors ? very low power consumption ? ratiometric 16 bit ? ?? ? ? adc ? linearity 14 bits ? internal clock oscillator ? serial data interface (i 2 c ? ?? ? bus) ? 256 bit eeprom memory description MAS6502 is a 16 bit analog-to-digital converter (adc), which employs a delta-sigma ( ) conversion technique. with the linear input signal range of 260 mv pp the linearity is 14 bits. MAS6502 is designed especially to meet the requirement for low power consumption, thus making it an ideal choice for battery powered systems. the MAS6502 is equipped with a standby function, i.e. the adc is in power down between each conversion. by utilizing this and overall low power consumption, current consumption values of 2.5 a (one pressure conversion in a second with full 14-bit accuracy) or less can be achieved. MAS6502 has an on-chip second order decimator filter to process the output of the secon d order -modulator. the adc also has four selectable input signal ranges with one optional offset level. an internal trimmed clock oscillator provides a system clock signal (dclk) eliminating the need for an external clock signal. a bi-directional i 2 c ? bus compatible 2-wire serial bus is used for configuring conversion parameters, starting conversion and reading out the a/d conversion result. MAS6502 has one input channel suitable for a piezoresistive pressure sensor. in addition t o pressure measurement the device can be configured also for temperature measurement. the 256-bit eeprom memory is available for storing trimming and calibration data on chip. features applications ? low standby current consumption 0.05 a typ ? very low supply current: 0.4 a?2.5 a typ ? supply voltage: 2.0 v?3.6 v ? ratiometric conversion ? selectable input signal ranges (vdd=2.35v): 325 mv pp , 220 mv pp , 150 mv pp , 100 mv pp ? selectable optional offset (vdd=2.35v): 33 mv selectable sensor resistance values 5 k , 4.5 k , 4 k , 3.4 k ? over sampling ratio: 512, 256, 128, 64 ? internal system clock signal 100 khz ? conversion times 0.8 ms? 10.6 ms typ ? 2-wire serial data interface (i 2 c ? bus) ? 256 bit eeprom memory ? good noise performance due to architecture ? calibrated piezoresistive pressure modules ? temperature measurement ? battery powered systems ? low frequency measurement applications ? current/power consumption critical systems ? industrial and process control applications in noisy environments i 2 c is a registered trademark of nxp.
da6502.008 29 november 2012 2 (20) block diagram figure 1. MAS6502 block diagram absolute maximum ratings all voltages with respect to ground parameter symbol conditions min max unit supply voltage v dd -0.3 5.0 v voltage range for all pins -0.3 v in + 0.3 v latchup current limit i lut for all pins, test according to jesd78a. -100 +100 ma junction temperature t jmax + 150 c storage temperature t s note 1 - 55 +125 c note 1. see eeprom memory data retention at hot tem perature. storage or bake at hot temperatures will reduce the wafer level trimming and calibration data retention time. note: the absolute maximum rating values are stress ratings only. functional operation of the device a t conditions between maximum operating conditions and absolute maximum ratings i s not implied and eeprom contents may be corrupted. exposure to these conditions for extended periods may affect device reliability (e.g. hot carrier degradation, oxide breakdown). ap plying conditions above absolute maximum ratings may be destructive to the devices. note: this is a cmos device and therefore it should be handled carefully to avoid any damage by static voltages (esd). recommended operation conditions parameter symbol conditions min typ max unit supply voltage v dd 2.0 2.35 3.6 v supply voltage at eeprom programming v dd t=+25c. note 1. 3.0 3.3 3.6 v operating temperature t a -40 +25 +85 c the device performance may deteriorate in the long run if the recommended operation conditions limits are continuously exceeded. note 1. it is recommended to program the eeprom at room tem perature. r2 r4 r1 r3 adc pi ni common vdd p t p t p t t gnd vdd control vrefn vrefp test i 2 c osc eeprom sda scl te3 eoc xclr te1 te2 MAS6502
da6502.008 29 november 2012 3 (20) electrical characteristics t a = -40 o c to +85 o c, vdd = 2.0v to 3.6v, typ t a = 27 o c, typ vdd = 2.35 v, r sensor = 4.5k unless otherwise noted parameter symbol conditions min typ max unit average adc current during conversion time i conv pressure mode temperature mode 80 100 185 200 330 350 a average adc current in pressure measurement during conversion period (no sensor current included) i adc_p 1 conversion/s, r sensor = 4.5 k , osr=512 osr=256 osr=128 osr=64 0.4 0.2 0.1 0.06 1.0 0.5 0.3 0.15 1.7 0.9 0.5 0.26 a average adc current in temperature measurement during conversion period (no sensor current included) i adc_t 1 conversion/s, r sensor = 4.5 k , osr=512 osr=256 osr=128 osr=64 0.8 0.4 0.2 0.1 2.0 1.0 0.5 0.3 3.5 1.8 0.95 0.5 a average supply current in pressure measurement during conversion period (including sensor bridge current) i savg_p 1 conversion/s, r sensor = 4.5 k , osr=512 osr=256 osr=128 osr=64 1.8 0.95 0.5 0.3 2.4 1.2 0.7 0.4 3.1 1.6 0.9 0.5 a average supply current in temperature measurement (including sensor bridge current) i savg_t 1 conversion/s, r sensor = 4.5 k , osr=512 osr=256 osr=128 osr=64 1.4 0.7 0.4 0.2 2.5 1.3 0.7 0.4 4.0 2.1 1.1 0.6 a peak supply current during pressure measurement i sc_p vdd = 2.35 v, r sensor = 4.5 k 0.6 0.7 0.85 ma peak supply current during temperature measurement i sc_t vdd = 2.35 v, r sensor = 4.5 k 0.2 0.3 0.46 ma standby current i ss vdd = 2.35 v note 1. 0.05 0.5 a internal system clock frequency dclk pressure measurement temperature measurement 85 42.5 100 50 113 56.5 khz pressure conversion time t conv_p dclk = 100 khz, osr=512 osr=256 osr=128 osr=64 4.6 2.4 1.2 0.7 5.3 2.7 1.5 0.8 6.2 3.2 1.7 0.95 ms temperature conversion time t conv_t dclk = 50 khz, osr=512 osr=256 osr=128 osr=64 9.3 4.8 2.5 1.4 10.6 5.5 2.9 1.6 12.4 6.4 3.4 1.9 ms vdd rise time for proper power on reset (por) t vdd_rise note 2. 400 ns note 1. leakage current may increase if digital inp ut voltages are not close to vdd (logic level high) or gnd (logic level low) note 2. device reset by using xclr pin or reset reg ister (30 hex ) is necessary in case the vdd rise time is longer than specified here.
da6502.008 29 november 2012 4 (20) electrical characteristics t a = -40 o c to +85 o c, vdd = 2.0v to 3.6v, typ t a = 27 o c, typ vdd = 2.35 v, r sensor = 4.5k unless otherwise noted parameter symbol conditions min typ max unit resolution n bit 16 bit v lsb osr=512 isr = 325 mv isr = 100 mv note 1. 5 1.5 v noise (one sigma) v n osr=512, isr = 325 mv 3.4 v rms 0.68 lsb accuracy osr = 512, t a = 27 o c isrlin = 260 mv 20 v integral nonlinearity inl osr=512, vdd = 2.35v, t a = 27 o c isrlin = 260 mv isrlin = 100 mv note 2. 2.7 6.2 6 1) 14 1) lsb vdd sensitivity in pressure mode vddsensp pressure mode, osr=512, isr = 325mv, t a = 27 o c vdd step 3.6v ? 2.0v 15 40 lsb vdd sensitivity in temperature mode vddsenst temperature mode, osr=512, isr = 325mv, t a = 27 o c vdd step 3.6v ? 2.0v 80 150 lsb linearity in bits lin isrlin = 260 mv, t a = 27 o c osr=512 osr=256 osr=128 osr=64 note 3. 14 13 12 10 bit input signal range isr 325 220 150 100 mv linear input signal range isrlin 10%...90% range (80%) of isr 260 176 120 80 mv input signal offset offset +33mv selection no offset selection 33 0 mv output code values code osr=512 osr=256 osr=128 osr=64 0 0 0 0 65152 32385 8001 1953 linear range output code values (10%...90% of whole code range) osr=512 osr=256 osr=128 osr=64 6515 3239 800 195 58637 29147 7201 1758 1) guaranteed by design note 1. isr (isrlin) and osr refer to the adc contr ol register bits, see table 2 on page 8. note 2. integral nonlinearity calculated from best fit line to linear input signal range containing 21 pcs analysis points . note 3. linearity in bits calculated from lin=log(c odelin/inl)/log(2)=log(80%*code max /inl)/log(2)
da6502.008 29 november 2012 5 (20) electrical characteristics t a = -40 o c to +85 o c, vdd = 2.0v to 3.6v, typ t a = 27 o c, typ vdd = 2.35 v, r sensor = 4.5k unless otherwise noted parameter symbol conditions min typ max unit temperature measurement resistors r 1 r 2 r 4 -19% 13900 30600 30600 +19% r 3 rsensor = 5 k rsensor = 4.5 k rsensor = 4 k rsensor = 3.4 k -19% 8900 9400 9900 10500 +19% temperature coefficient of temperature measurement resistors tc r -180 ppm / c eeprom size note 1. 256 bit eeprom data write time note 2. 16 ms eeprom data erase time note 3. 8 ms eeprom data retention ta = +85 c ta = +125 c 10 24 1 years note 1. 8 bits out of 256 bits are reserved for int ernal oscillator trimming. the remaining 248 bits c an be freely used for storing calibration coefficients and other data. note 2. there should be at least a 16ms delay after each eeprom write since eeprom programming can tak e up to 16ms. note 3. there should be at least a 8ms delay after each eeprom erase since eeprom erasing can take up to 8ms. digital inputs t a = -40 o c to +85 o c, vdd = 2.0v to 3.6v, typ t a = 27 o c, typ vdd = 2.35 v, r p = 4.7k ( i 2 c bus pull up ) unless otherwise noted parameter symbol conditions min typ max unit input high voltage v ih 80% vdd 100% vdd v input low voltage v il 0% vdd 20% vdd v serial bus clock frequency f scl 400 khz xclr reset pulse length t xclr xclr low pulse 200 ns xclr pin pull up current i pull_up xclr=0v -1 -8 -80 a digital outputs t a = -40 o c to +85 o c, vdd = 2.0v to 3.6v, typ t a = 27 o c, typ vdd = 2.35 v, r p = 4.7k ( i 2 c bus pull up ) unless otherwise noted parameter symbol conditions min typ max unit output high voltage v oh i source =0.6ma 80% vdd 100% vdd v output low voltage v ol i sink =0.6ma 0% vdd 20% vdd v signal rise time (from 10% to 90%) t r eoc pin, c l =50pf sda pin, c b =50pf 14 550 ns signal fall time (from 90% to 10%) t f eoc pin, c l =50pf sda pin, c b =50pf 11 11 ns
da6502.008 29 november 2012 6 (20) operating modes MAS6502 has two operating modes, pressure and temperature measurement mode. in the pressure mode the pressure dependent sensor bridge voltage is connected to the adc input. in the temperature measurement mode the resistive sensor is connected into a wheatstone resistor bridge circuit together with four internal resistor s (see temperature measurement configuration in the application information chapter) and the temperature dependent bridge output voltage is connected to the adc input. switching between pressure and temperature measurement modes is done via the single adc control register. the measurement configuration includes selection of over sampling ratio, input signal range, offset and sensor resistance. by writing an 8-bit configuration data to the adc control register a new a/d conversion is started. see further details in the adc control register chapter. MAS6502 includes a 256-bit eeprom memory for storing trimming and calibration data on chip. the first 8-bits of eeprom are reserved for internal oscillator trimming but the remaining 248-bits are free for calibration and other data. the stored calibration data should comprise of calibration and temperature compensation coefficients which can be used to calculate accurat e calibrated pressure and temperature measurement results from the non-calibrated measurement results. all calculations need to be done in the external micro controller unit (mcu). a calibrated MAS6502 sensor system is operated as illustrated in figure 2. the calibration and compensation coefficients need to be read to the mcu memory only once. from each pair of pressure and temperature measurements results the accurate pressure and temperature values are then calculated by using the external mcu. all communication with MAS6502 is done using the bi-directional i 2 c ? bus compatible 2-wire serial bus. starting an a/d conversion, reading out the conversion result and reading and writing data from and to the eeprom memory are all accomplished via serial bus communication. in addition to the i 2 c ? bus the digital interface includes also end-of-conversion (eoc) and master reset (xclr) pins. see a/d conversion in the serial data interface (i 2 c ? bus) control chapter. figure 2. flow chart for a calibrated MAS6502 sensor system start read eeprom calibration data measure pressure measure temperature calculate calibrated temperature calculate temperature compensated pressur e
da6502.008 29 november 2012 7 (20) register and eeprom data addresses MAS6502 includes a 32 bytes (256 bits) eeprom data memory. the first eeprom byte at address 40 hex is reserved for internal clock oscillator frequency trimming. the remaining 31 bytes (248 bits) in memory addresses 41 hex ?5f hex are free for storing sensor calibration and other data. MAS6502 also contains ten 8-bit registers. addressing the reset register triggers device reset . see table 1 for register and eeprom data addresses. table 1. register and eeprom data addresses a7 a6 a5 a4 a3 a2 a1 a0 hex (x=0) description note x 0 0 0 0 0 0 0 00 eeprom; erase internal clock osc illator trimming, reserved! e x 0 0 a4 a3 a2 a1 a0 01?1f eeprom; erase data at ad dress [a4:a0] e x 1 0 0 0 0 0 0 40 eeprom; read or write internal c lock oscillator trimming, reserved! e x 1 0 a4 a3 a2 a1 a0 41?5f eeprom; read or write da ta at address [a4:a0] e x x 1 1 0 0 0 0 30 reset register; contains no data , write any dummy data for a reset r x x 1 1 0 1 1 1 37 test and trim control register r x x 1 1 1 0 0 0 38 oscillator frequency control reg ister r x x 1 1 1 0 0 1 39 data input register for eeprom r x x 1 1 1 0 1 0 3a control register for eeprom r x x 1 1 1 0 1 1 3b write and erase enable for eepro m r x x 1 1 1 1 0 0 3c status register for eeprom r x x 1 1 1 1 0 1 3d msb conversion result r x x 1 1 1 1 1 0 3e lsb conversion result r x x 1 1 1 1 1 1 3f adc control register r x = don?t care, e = eeprom, r= register eeprom addresses 01 hex ?1f hex are used for erasing the data at the addressed bytes whereas eeprom addresses 41 hex ?5f hex are for read/write of addressed bytes. in case of writing t he data the eeprom address or block when necessary is erased automatically before writing new data on it. there should be at least a 16ms delay after each eeprom write since eeprom programming can take up to 16ms. for eeprom erase this delay should be at least 8ms. reset register (30 hex ) does not contain any data. any dummy data written to this register forces a reset. a reset initializes all control registers (addresses 37 hex ?3f hex ) to a zero value. test and trim control register (37 hex ) is for testing and trimming purposes. the oscillator frequency control register (38 hex ) is used only during internal clock oscillator trimming . during trimming this register value is iterated to find desired oscillator frequency. when the correct valu e is found it can be written to the eeprom internal clock oscillator trimming register (40 hex ). in normal operation the trimming value is automatically read from the eeprom memory during startup. note: there is no need for internal oscillator trimming since this is done during wafer level testing. eeprom data input register (39 hex ) is automatically used in all eeprom data transfers. there is no need to address this register manually except when doing a ?block write? when data must be written to the input register before giving the block write command. eeprom control register (3a hex ) is for special eeprom functions like block erase, block write and test modes. the eeprom write and erase enable register (3b hex ) is used to protect the calibration memory against accidental write/erase. after reset (power on reset, xclr) this register is set to %00000000 (00 hex ) and the eeprom memory erase/write is disabled. the eeprom erase/write is enabled only when this register value is set to %01010101 (55 hex ). eeprom status register (3c hex ) is used for eeprom error correction status. the msb and lsb conversion result registers (3d hex and 3e hex ) contain the last 16-bit a/d conversion result. the adc control register (3f hex ) is used for configuring and starting a/d conversions. see chapter adc control register for details.
da6502.008 29 november 2012 8 (20) adc control register table 2. MAS6502 adc control register bit description bit number bit name description value function 7-6 osrs over sampling ratio (osr) selection 11 01 10 00 osr = 512 osr = 256 osr = 128 osr = 64 5 pts pressure/temperature selection 1 0 pressure measurement temperature measurement 4-3 isr input signal range 11 10 01 00 325 mv (260 mv linear range) 220 mv (176 mv linear range) 150 mv (120 mv linear range) 100 mv (80 mv linear range) 2 osselect offset selection 1 0 +33 mv no offset 1-0 rsselect sensor resistance selection for temperature measurement mode 11 10 01 00 rsensor = 3.4 k rsensor = 4.0 k rsensor = 4.5 k rsensor = 5.0 k MAS6502 has an adc control register for configuring the measurement setup. a new conversion is started simply by writing 8-bit configuration data to the adc control register. see table 2 for adc control register bit definitions. a dc control register values are set via the 2-wire seri al data interface. note: the device should not be addressed via serial bus before the conversion has been ended. reading or writing to device during the conversion may corrupt the conversion result. the first two osrs bits of the control register defines four selectable over sampling ratios. the higher the osr is set the better is the adc resolution, but the conversion time gets longer. the pts bit selects between pressure and temperature measurement. for temperature measurement the sensor is connected in the wheatstone bridge configuration together with four integrated resistors. see figure 5 on page 15. the isr bits selects between four a/d input signal ranges. the osselect bit is used to enable or disable an offset for the input signal. the two rsselect bits selects between four sensor resistance options. the selection sets the internal r3 resistor value to balance the wheatstone bridge circuit formed by the sensor resistance and four internal resistors r1, r2, r3 and r4. see electrical characteristics for resistor values.
da6502.008 29 november 2012 9 (20) test and trim control register pins te1 (output), te2 (input) and te3 (input/output) are used for testing purposes. in normal use these pins are left floating. te2=0: normal operation, (pull down resistor on chip). te1 is driven high. te2=1: the converter is in continuous integration mode. the sigma - delta modulator latch output is connected to the te1 pin and te1 is also connected to the on-chip decimator input. this way an external decimator can use the te1 pin signal and the results from the external and the on-chip decimator can be compared. oscillator trimming: test register reg37 hex bit 0 (measosc) turns the oscillator on and connects the oscillator output to the te3 pin for frequency measurement. reg37 hex bit 2 (trimallreg) is used for oscillator trimming. when set to 1, the six least significant bits oscf(5:0) in reg38 hex are used to adjust the oscillator frequency (see table 4). when the right frequency is obtained the trim value can be programmed to the eeprom (address 40 hex ). the nominal frequency, 200khz, is designed to occur when oscf(5:0) = 28 hex . note: there is no need for internal oscillator trimming since this is done during wafer level testing. if trimallreg=0 then data from eeprom address 40 hex will be used to adjust the oscillator. when bit 1 (extclk) in test register reg37 hex is set to 1 the internal oscillator is turned off and an external clock signal can be connected to the te3 pin. this enables the use of an external conversion clock. test register reg37 hex bit 4 (iclkdiv) enables clock division, forcing the a/d conversion to run a t half the speed. clock division is also used when an external clock is used (extclk bit is set). test register reg37 hex bit 3 (isampl) enables refreshing sensor sample only at every fourth clock cycle for additional power saving but with increase d sampling noise level. table 3. MAS6502 test and trim control register (37 hex ). only bits (4:0) are used. bit number bit name description value function 7?5 x - 4 iclkdiv additional clock division 0 1 100khz/50khz to sdm 50khz/25khz to sdm 3 isampl sample refresh mode selection 0 1 refresh at every clock cycle refresh at fourth clock cycle 2 trimallreg trim bits from register 0 1 normal operation osc trim register in use 1 extclk external clock mode 0 1 normal operation external clock from te3 0 measosc oscillator test mode 0 1 normal operation osc output to te3 x = don?t care, sdm = sigma delta modulator table 4. MAS6502 oscillator frequency control register (38 hex ). only bits (5:0) are used. bit number bit name description value function 7?6 x - 5?0 oscf 11111 ? 00000 200khz oscillator frequency trimming value x = don?t care note: it is recommended to not change oscillator fr equency trimming value since trimming is done durin g wafer level testing.
da6502.008 29 november 2012 10 (20) eeprom special functions register (3a hex ) controls the special eeprom functions that includes eeprom block erase, write and test functions. see table 5. the eeprom control register functions are not needed in normal eeprom use such as read and write operations. the 256-bit eeprom consists of two 128-bit blocks, so block erase and block write applies only to one half of the eeprom, selectable by the a4 address bit (see table 1). to erase or write the whole eeprom, block erase or write needs to be done twice: for a4=0 and for a4=1. it is recommended to not use block erase or write functions to avoid accidental internal oscillator trimming data overwriting at a4=0 memory block. setting the eeprom control register bit 7 (ebe) to 1 will erase the eeprom memory block (128 bits) specified by the a4 bit. erased memory block consists of zeroes. setting bit 6 (ebw) to 1 will force the eeprom memory block specified by the a4 bit to be programmed to the same 8-bit word found in the eeprom data input register (39 hex ). note: after block operations the block erase (ebe) or write (ebw) control bit need to be written back to value 0 to return normal operation. table 5. MAS6502 eeprom control register (3a hex ) bit number bit name description value function 7 ebe eeprom block erase 0 1 - erase 128-bit block of eeprom 6 ebw eeprom block write 0 1 - write eeprom data input register (39 hex ) data into 128-bit block of eeprom 5 eetest eeprom test mode enable 0 1 - test mode enabled 4-3 vee[1:0] eeprom test read mode selection 11 10 00 01 internal high test read internal low test read forbidden forbidden 2 cptest charge pump test input pin 0 1 programming allowed output protection of cp disabled 1 dma direct memory access tbd tbd 0 parity parity access tbd tbd tbd = to be defined the MAS6502 eeprom status register (3c hex ), bits (7:6), reflect the eeprom operation status. see table 6. this register can be used to verify that the eeprom operation has been accomplished without errors. table 6. MAS6502 eeprom status register (3c hex ). only bits (7:6) are used. bit number bit name description value function 7 error eeprom error detection 0 1 no errors 1 (or more) data error(s) 6 ded eeprom double error detection 0 1 no errors 2 (or more) data errors 5-0 x - x = don?t care
da6502.008 29 november 2012 11 (20) serial data interface (i 2 c ? ?? ? bus) control serial interface MAS6502 has an i 2 c ? bus compatible two wire serial data interface comprising of serial clock (scl) and bi-directional serial data (sda) pins. bo th the scl & sda lines, in the i 2 c ? bus, are of open- drain design, thus, external pull-up resistors are needed. the serial data interface is used to configure and start the a/d conversion and read the measurement result when the a/d conversion has been finished. the digital interface includes also end of conversi on (eoc) and master reset (xclr) pins. the eoc goes high when the a/d conversion has finished. the xclr signal is active low and used to reset the a/d converter. a reset initializes the serial communication bus and sets internal registers and counters to value 00 hex. after connecting the supply voltage to MAS6502, and before starting operating the device via the serial bus, it is required to re set the device with the xclr reset pin or using reset register (30 hex ) if the supply voltage rise time has been longer than 400 ns. if the supply voltage rise time is shorter than this making an external reset is not necessary since the device is automatically reset by the power on reset (por) circuitry. it is however recommended to use the xclr reset feature to solve unexpected error state conditions. the xclr pin can be left unconnected when not used. it has internal pull up to vdd. see electrica l characteristics for the xclr pin pull up current. device address the i 2 c ? bus definition allows several i 2 c ? bus devices to be connected to the same bus. the devices are distinguished from each other by unique device address codes. MAS6502 device address is shown in table 7. the lsb bit of the device address defines whether the bus is configured for read (1) or write (0) operation. table 7. MAS6502 device address a7 a6 a5 a4 a3 a2 a1 w/r 1 1 1 0 1 1 1 0/1 i 2 c ? ?? ? bus protocol definitions data transfer is initiated with a start bit (s) whe n sda is pulled low while scl stays high. then, sda sets the transferred bit while scl is low and the data is sampled (received) when scl rises. when the transfer is complete, a stop bit (p) is sent by releasing the data line to allow it to be pulled up while scl is constantly high. figure 3 shows the start (s) and stop (p) bits and a data bit. data must be held stable at the sda pin when scl is high. data at the sda pin can change value only when scl is low. each sda line byte must contain 8-bits when the most significant bit (msb) is always first. each by te has to be followed by an acknowledge bit (see further below). the number of bytes transmitted per transfer is unrestricted. sda scl s p 10 figure 3. i 2 c ? bus protocol definitions bus communication includes acknowledge (a) and not acknowledge (n) messages. to send an acknowledge the receiver device pulls the sda low for one scl clock cycle. for not acknowledge (n) the receiver device leaves the sda high for one scl clock cycle in which case the master can then generate either a stop (p) bit to abort the transfe r, or a repeated start (sr) bit to start a new transfe r. abbreviations: a= acknowledge by receiver n = not acknowledge by receiver s = start sr = repeated start p = stop = from master (mcu) to slave (MAS6502) = from slave (MAS6502) to master (mcu)
da6502.008 29 november 2012 12 (20) serial data interface (i 2 c ? ?? ? bus) control conversion starting ? write sequence conversion is started by writing configuration bits into the adc control register. the write sequence i s illustrated in table 8. table 8. MAS6502 i 2 c ? bus write sequence s aw a ac a dc a p abbreviations: aw = device write address (%1110 1110) ar = device read address (%1110 1111) ac = adc control register address (%1111 1111) ax = msb (x=m, %1111 1101) or lsb (x=l, %1111 1110) adc result register address dc = adc control register data dx = msb (x=m) or lsb (x=l) adc result register data each serial bus operation, like write, starts with the start (s) bit (see figure 3). after start (s) the MAS6502 device address with write bit (aw, see table 7) is sent followed by an acknowledge (a). after this the adc control register address (see table 1) is sent and followed by an acknowledge (a). next the adc control register data (dc, see table 2) is written and followed by an acknowledge (a). finally the serial bus operation is ended with a stop (p) command (see figure 3). a/d conversion after power-on-reset or external reset (xclr) the eoc output is high. after an a/d conversion is started the eoc output is set low until the conversion is finished and the eoc goes back high, indicating that the conversion is done and data is ready for reading. the eoc is set low only by starting a new conversion. to save power the internal oscillator runs only during conversion. during the a/d conversion period the input signal i s sampled continuously leading to an output conversion result that is a weighted average of the samples taken. note: the device should not be addressed via serial bus before the conversion has ended. reading or writing to the device during the conversion may corrupt the conversion result. conversion result ? read sequence table 9 shows a general control sequence for a single register data read. table 9. MAS6502 i 2 c ? bus single register (address ax) read sequence s aw a ax a sr ar a dx n p table 10 shows the control sequence for reading the 16-bit a/d conversion result from both the msb and lsb data registers. the lsb register data (dl) can be read right after the msb register data (dm) in case the read sequence is continued (not ended by a stop bit p) since the register address is automatically incremented to point to the next register address (in this case to point to the lsb data register). table 10. MAS6502 i 2 c ? bus msb (first) and lsb (second) a/d conversion r esult read sequence s aw a am a sr ar a dm a dl n p
da6502.008 29 november 2012 13 (20) application information figure 4. typical application circuit together with a resistive pressure sensor, MAS6502 can be used in pressure measurement applications. an external micro-controller can control the MAS6502 via an i 2 c ? serial interface. note that the i 2 c ? serial interface requires suitable pull up resistors connected to the sda and scl pins (see figure 4). note that if there is only a s ingle master device in the serial bus the master?s scl output can be push-pull output stage making the scl pull-up resistor unnecessary. the sensor is connected between the power supply voltage (vdd) and MAS6502 signal ground (common) which can be internally connected to ground (gnd). the sensor output is read as a differential signal through pi (positive input) and ni (negative input) to the converter in MAS6502. in the pressure measurement mode, the switches marked ?p? are closed and the sensor output is fed through to the adc. in the temperature measurement mode, the switches marked ?t? are closed and the voltage at the adc input is determined by the internal resistor array and the temperature-dependent resistance of the sensor. in this configuration the sensor bridge is connected a s part of a wheatstone resistor bridge circuit where the other four resistors (r1, r2, r3, r4) are insid e the ic. to guarantee conversion accuracy a supply voltage decoupling capacitor of 4.7 f or more should be placed between vdd and gnd of MAS6502 (see c vdd in figure 4). accuracy improvement ? averaging an averaging technique can be used to remove conversion error caused by noise and thus improve measurement accuracy. by doing several a/d conversions and calculating the average result it?s possible to average out noise. theoretically random noise is reduced by a factor n where n is the number of averaged samples. a/d converter nonlinearities cannot be removed by averaging. gnd r2 r4 r1 r3 adc pi ni common vdd p t p t p t t gnd vdd control sensor vrefn vrefp test i 2 c osc eeprom sda scl te3 eoc xclr te1 te2 MAS6502 mcu optional vdd gnd i/o i/o i / o i/o gnd gnd vdd vdd r p 4.7k r p 4.7k c vdd 4.7 ? vdd note 1. it is recommended to use the xclr reset feature to solve unexpected error state conditions. the xclr pin can be left unconnected if not used. it has internal pull up to vdd . note 1
da6502.008 29 november 2012 14 (20) application information input signal range definitions the input signal voltage polarity is from positive input pi to the negative input ni. MAS6502 has inpu t signal range (isr) and offset (offset) selection options t hat determines the input signal range of the a/d co nverter. the minimum and maximum input signal values in the linear input signal range (isrlin) are calculated a s follows. 2 _ isrlin offset v min in ? = equation 1. 2 _ isrlin offset v max in + = equation 2. table 11 shows minimum and maximum input signal val ues in the linear input signal range at different i nput signal range and offset selection combinations. table 11. minimum and maximum input signal values in the lin ear input signal range offset isr isrlin vin_min vin_max [mv] [mv] [mv] [mv] [mv] 0 325 260 -130 130 33 325 260 -97 163 0 220 176 -88 88 33 220 176 -55 121 0 150 120 -60 60 33 150 120 -27 93 0 100 80 -40 40 33 100 80 -7 73 the digital a/d conversion result, code, depends on the input signal as follows. ?? ? ?? ? ? ? + ? = isr offset v code code in max 5.0 equation 3. code = digital a/d-conversion output code code max = a/d-converter maximum code (minimum code is zero ) see page 4 electrical characteristics for code max values at different over sampling ratio (osr) sele ctions. pressure measurement configuration piezoresistive absolute pressure sensor can be mode led roughly with following signal voltage character istic when including only first order pressure and temper ature characteristics.. ( ) ( ) ( ) ( ) ( ) ?? ? ?? ? ? ? + ? + ? ? ? + ? ? = ref os fs ref fs ref in t t tc os p p t t tc fs vdd vdd t p v 1 1 , equation 4. vdd = supply voltage vdd ref = reference supply voltage at which the sensor par ameters (fs, os) have been specified (often 5v) p = pressure [bar] p fs = full-scale pressure range [bar] fs = full-scale span [v] os = zero pressure offset [v] tc fs = full-scale span temperature coefficient [ppm/ c] tc os = offset temperature coefficient [ppm/ c] t ref = reference temperature for resistor values [ c] t = actual temperature to be measured [ c] the above linear approximation includes sensor full -scale span and offset signal temperature dependenc ies.
da6502.008 29 november 2012 15 (20) application information temperature measurement configuration in the temperature measurement configuration the pi ezoresistive sensor r s is connected into a wheatstone resistor bridge configuration together with four in ternal resistors r1, r2, r3 and r4. see figure 5. figure 5. temperature measurement configuration in the temperature measurement configuration the a/ d converter input signal has the following characte ristics. ( ) ( ) [ ] ( ) [ ] ? ? ? ?? ? ? ? ? ?? ? + + ? ? + ? ? ? + ? ? + ? = 1 1 1 1 1 1 4 3 4 2 1 r r t t tc r t t tc r r r vdd t v ref r ref s s in equation 5. vdd = supply voltage r s = sensor bridge resistance [ ] r 1, 2, 3, 4 = internal resistors [ ] tc s = sensor resistance temperature coefficient [ppm/ c] tc r = internal resistor temperature coefficient [ppm/ c] t ref = reference temperature for resistor values [ c] t = actual temperature to be measured [ c] from equation 5 we get that the temperature signal has a rising temperature dependency vs. temperature when the sensor resistance has a positive temperature co efficient tc s >0. with negative sensor resistance temperature coefficient tc s <0 the signal has a falling temperature dependency vs. temperature. see the signal illustration in figure 6. figure 5. temperature signal dependency of sensor resistance temperature coefficient gnd r2 r4 r1 r3 pi ni vdd r s v in
da6502.008 29 november 2012 16 (20) MAS6502ba1 in qfn-16 4x4x0.75 package MAS6502 xxxxx yyww ba1 gnd 13 8 te1 12 common 11 pi 10 te2 9 ni 5 scl eoc 16 vdd 1 te3 2 xclr 3 sda 4 top marking information: MAS6502 = product number, ba1 = version number yyww = year week xxxxx = lot number qfn-16 4x4x0.75 pin description pin name pin type function notes vdd 1 p power supply voltage te3 2 di/o test pin 3 for internal clock oscillator 1 xclr 3 di reset i2c, stop conversion 2 sda 4 di/o serial bus data input/output scl 5 di serial bus clock 6 nc 7 nc te1 8 di/o test pin 1 1 ni 9 ai adc negative input te2 10 di test pin 2 1 pi 11 ai adc positive input common 12 ai sensor ground gnd 13 g power supply ground 14 nc 15 nc eoc 16 do end of conversion nc = not connected, p = power, g = ground, do = di gital output, di = digital input, ao = analog outpu t note 1: test pins te1, te2 and te3 must be left floating. note 2: xclr pin can be left unconnected when not used. it has internal pull up to vdd.
da6502.008 29 november 2012 17 (20) d/2 e / 2 seating plane a 1 side view top view d2 d2 / 2 e 2 / 2 e 2 b bottom view d a 3 pin 1 mark area a exposed pad shape of pin #1 identification is optional l detail a terminal tip package center line x or y e e/2 detail a package (qfn-16 4x4x0.75) outline symbol min nom max unit package dimensions a 0.700 0.750 0.800 mm a1 0.000 0.020 0.050 mm a3 0.203 ref mm b 0.250 --- 0.350 mm d 3.950 4.000 4.050 mm d2 (exposed.pad) 2.700 --- 2.900 mm e 3.950 4.000 4.050 mm e2 (exposed.pad) 2.700 --- 2.900 mm e 0.650 bsc mm l 0.350 --- 0.450 mm dimensions do not include mold or interlead flash, protrusions or gate burrs.
da6502.008 29 november 2012 18 (20) user direction of feed w p o p 1 d 0 x x e f t b 0 k 0 r 0.25 typ p 2 a 0 soldering information u for lead-free / green qfn 4mm x 4mm resistance to soldering heat according to rsh test iec 68-2-58/20 maximum temperature 260 c maximum number of reflow cycles 3 reflow profile thermal profile parameters stated in ipc/jedec j-std-020 should not be exceeded. http://www.jedec.org lead finish solder plate 7.62 - 25.4 m, material matte tin embossed tape specifications orientation on tape dimension min/max unit a o 4.30 0.10 mm b o 4.30 0.10 mm d o 1.50 +0.1/-0.0 mm e 1.75 mm f 5.50 0.05 mm k o 1.10 0.10 mm p o 4.0 mm p 1 8.0 0.10 mm p 2 2.0 0.05 mm t 0.3 0.05 mm w 12.00 0.3 mm all dimensions in millimeters
da6502.008 29 november 2012 19 (20) d a b c n w 1 w 2 tape slot for tape start components trailer leader carrier tape cover tape start end reel specifications dimension min max unit a 330 mm b 1.5 mm c 12.80 13.50 mm d 20.2 mm n 100 mm w 1 (measured at hub) 12.4 14.4 mm w 2 (measured at hub) 18.4 mm trailer 160 mm leader 390, of which minimum 160 mm of empty carrier tape sealed with cover tape mm reel material: conductive, plastic antistatic or st atic dissipative carrier tape material: conductive cover tape material: static dissipative
da6502.008 29 november 2012 20 (20) ordering information product code product description MAS6502ba1wa100 piezoresistive sensor signal interface ic ews-tested wafer, thickness 480 m. MAS6502ba1wa105 piezoresistive sensor signal interface ic dies on waffle pack, thickness 480 m MAS6502ba1q1706 piezoresistive sensor signal interface ic qfn-16 4x4x0.75, pb-free, rohs compliant, tape & reel, 1000/3000 pcs components on reel contact micro analog systems oy for other wafer thi ckness options. local distributor micro analog systems oy contacts micro analog systems oy kutomotie 16 fi-00380 helsinki, finland tel. +358 10 835 1100 fax +358 10 835 1109 http://www.mas-oy.com notice micro analog systems oy (mas) reserves the right to make changes to the products contained in this dat a sheet in order to improve the design or performance and to supply the best possib le products. mas assumes no responsibility for the use of any circuits shown in this data sheet, conveys no license under any patent or other rights unless otherwise specified in this dat a sheet, and makes no claim that the circuits are free from patent infringement. applica tions for any devices shown in this data sheet are for illustration only and mas makes no claim or warranty that such applications will be su itable for the use specified without further testin g or modification. mas products are not authorized for use in safety-c ritical applications (such as life support) where a failure of the mas product would reasonably be expected to cause severe personal inj ury or death. buyers represent that they have all n ecessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely respons ible for all legal, regulatory and safety- related requirements concerning their products and any use of mas products in such safety-critical app lications, notwithstanding any applications-related information or support that ma y be provided by mas. further, buyers must fully in demnify mas and its representatives against any damages arising out of the use of mas p roducts in such safety-critical applications. mas products are neither designed nor intended for use in military/aerospace applications or environme nts. buyers acknowledge and agree that any such use of mas products which mas h as not designated as military-grade is solely at th e buyer's risk, and that they are solely responsible for compliance with all legal an d regulatory requirements in connection with such u se. mas products are neither designed nor intended for use in automotive applications or environments. bu yers acknowledge and agree that, if they use any non-designated products in automoti ve applications, mas will not be responsible for an y failure to meet such requirements.

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