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document number: mpl115a1 rev. 7, 02/2013 freescale semiconductor data sheet: technical data ? 2009-2013 freescale semiconducto r, inc. all ri ghts reserved. miniature spi digital barometer the mpl115a1 is an absolute pressure s ensor with a digital spi output targeting low cost applications. a mini ature 5 x 3 x 1.2 mm lga pa ckage is ideally suited for the space constrained requirements of portable electronic devices. low current consumptions of 5 a during active mode and 1 a during shutdown (sleep) mode are essential when focusing on low-power applications. the wide operating temperature range spans from -40c to +105c to fit demanding environment conditions. the mpl115a1 employs a mems pressure sensor with a conditioning ic to provide accurate pressure measurement s from 50 to 115 kpa. an integrated adc converts pressure and temperature sensor readings to digitized outputs via a spi port. factory calibration data is stored internally in an on-board rom. utilizing the raw sensor output and calib ration data, the host microcontroller executes a compensation algorithm to render compensated absolute pressure with 1 kpa accuracy. the mpl115a1 pressure sensor?s small form factor, low power capability, precision, and digital output optimize it for barometric measurement applications. features ? digitized pressure and temperature information together with programmed calibration coefficients for host micro use. ? factory calibrated ? 50 kpa to 115 kpa absolute pressure ? 1 kpa accuracy ? 2.375v to 5.5v supply ? integrated adc ? spi interface ? monotonic pressure and temperature data outputs ? surface mount rohs compliant package application examples ? barometry (portable and desktop) ? altimeters ? weather stations ? hard-disk drives (hdd) ? industrial equipment ? health monitoring ? air control systems ordering information device name package options case no. # of ports pressure type digital interface none single dual gauge differential absolute mpl115a1 tray 2015 ? ? spi mpl115a1t1 tape & reel (1000) 2015 ? ? spi mpl115a1 50 to 115 kpa top view lga package 5.0 mm x 3.0 mm x 1.2 mm pin connections 1 dout din vdd cap shdn gnd cs sclk 2 3 4 8 7 6 5
sensors 2 freescale semiconductor, inc. mpl115a1 1 block diagram and pin descriptions figure 1. block diagram and pin connections table 1. pin description pin name function 1 vdd vdd power supply connection: vdd range is 2.375v to 5.5v. 2 cap external capacitor: output decoupling capacitor for main internal regulator. connect a 1 f ceramic capacitor to ground. 3 gnd ground 4 shdn shutdown: connect to gnd to disable the device. when in shut down the part draws no more than 1 a supply current and all communications pins (cs , sclk, dout, din) are high impedance. connect to vdd for normal operation. 5 cs cs : chip select line. 6 dout dout: serial data output 7 din din: serial data input 8 sclk spi: serial clock input. diff amp temp sensor mux adc din gnd vdd dout temperature pressure coefficient storage addr addr addr addr addr spi interface shdn cs cap sclk diff amp temp sensor mux adc din gnd vdd dout temperature pressure coefficient storage addr addr addr addr addr addr addr addr spi interface shdn cs cap sclk vdd cap shdn din cs dout gnd sclk c 1 f 1 f microcontroller
sensors freescale semiconductor, inc. 3 mpl115a1 2 mechanical and elect rical specifications 2.1 maximum ratings voltage (with respect to gn d unless otherwise noted) v dd ..................................................................................................................... -0.3 v to +5.5 v shdn , sclk, cs , d in , d out ......................................................................-0.3 v to v dd +0.3 v operating temperature range .......................................................................... -40c to +105c storage temperature range ............................................................................. -40c to +125c overpressure................................................................................................................ 100 0 kpa 2.2 operating characteristics (v dd = 2.375 v to 5.5 v, t a = -40c to +105c, unless otherwise noted. typical values are at v dd = 3.3 v, t a = +25c. ref parameters symbol conditions min typ max units 1 operating supply voltage v dd 2.375 3.3 5.5 v 2 supply current i dd shutdown (shdn = gnd) ? ? 1 a standby ? 3.5 10 a average ? at one measurement per second ? 5 ? a pressure sensor 3 range 50 ? 115 kpa 4 resolution ?0.15?kpa 5 accuracy -20oc to 85oc ? ? 1 kpa 6 conversion time (start pressure and temperature conversion ) tc time between start convert command and data available in the pressure and temperature registers ?1.63ms 7 wakeup time tw time between leaving shutdown mode (shdn goes high) and communicating with the device to issue a command or read data. ?35ms spi inputs: sclk, cs , d in 8 sclk clock frequency f sclk (1) 1.nominal maximum spi clock frequency. ??8mhz 9 low level input voltage vil ??0.3v dd v 10 high level input voltage vih 0.7v dd ?? v spi outputs: d out 11 low level output voltage vol1 at 3 ma sink current 0 ? 0.4 v vol2 at 6 ma sink current 0 ? 0.6 12 high level output voltage voh1 at 3 ma source current v dd ? 0.4 v ? ? v
sensors 4 freescale semiconductor, inc. mpl115a1 3 overview of functions/operation figure 2. sequence flow chart the mpl115a interfaces to a host (or system) microcontroller in the user?s application. all communications are via spi. a typic al usage sequence is as follows: initial power-up all circuit elements are active. spi port pins are high impedan ce and associated registers are cleared. the device then enters standby mode. reading coefficient data the user then typically accesses the part and reads the coefficien t data. the main circuits within the slave device are disable d during read activity. the coefficients are usually stored in the host microcontoller local memory but can be re-read at any tim e. reading of the coefficients may be executed only once and the values stored in the host microcontroller. it is not necessary to read this multiple times because the coefficients within a devi ce are constant and do not change. however, note that the coefficients will be different from device to device, and cannot be used for another part. data conversion this is the first step that is performed each time a new pressure reading is required which is initiated by the host sending th e convert command. the main system circuits are activated (w ake) in response to the command and after the conversion completes, the result is placed into the pr essure and temperatur e adc output registers. the conversion completes within the maximum conversion time, tc (see row 6 , in the operating characteristics table). the device then enters standby mode. compensated pressure reading after the conversion has been given sufficient time to complete, the host microcontroller reads the result from the adc output registers and calculates the compensated pressure, a barome tric/atmospheric pressure value which is compensated for changes in temperature and pressure sensor linearity. this is done using the coefficient data from the mpl115a and the raw sampled pressure and temperature adc output values, in a compensa tion equation (detailed later). note that this is an absolute pressure measurement with a vacuum as a reference. from this step the host controller may either wait and then retu rn to the data conversion step to obtain the next pressure read ing or it may go to the shutdown step. reading coefficient data data conversion initial powerup compensated pressure reading shutdown
sensors freescale semiconductor, inc. 5 mpl115a1 shutdown for longer periods of inactivity the user may assert the shdn input by driving this pin low to reduce system power consumption. this removes power from all internal circuits, including any re gisters. in the shutdown state, the pressure and temperature registers will be reset, losing any previous adc output values. this step is exited by taking the shdn pin high. wait for the maximum wakeup time, tw (see row 7 , in the operating characteristics table), after which another pressure reading can be taken by transitioning to the data conversion step. for values with less than 16 bits, the lower lsbs are zero. for ex ample, c12 is 14 bits and is stored into 2 bytes as follows: c12 ms byte = c12[13:6] = [c12 b13 , c12 b12 , c12 b11 , c12 b10 , c12 b9 , c12 b8 , c12 b7 , c12 b6 ] c12 ls byte = c12[5:0] & ?00? = [c12 b5 , c12 b4 , c12 b3 , c12 b2 , c12 b1 , c12 b0 , 0 , 0] 3.1 pressure, temperature and coef ficient bit-width specifications the table below specifies the initial coefficient bit-width spec ifications for the compensation algorithm and the specification s for pressure and temperature adc values. table 2. device memory map address name description 0x00 padc_msb 10-bit pressure adc output value msb 0x01 padc_lsb 10-bit pressure adc output value lsb 0x02 tadc_msb 10-bit temperature adc output value msb 0x03 tacd_lsb 10-bit temperature adc output value lsb 0x04 a0_msb a0 coefficient msb 0x05 a0_lsb a0 coefficient lsb 0x06 b1_msb b1 coefficient msb 0x07 b1_lsb b1 coefficient lsb 0x08 b2_msb b2 coefficient msb 0x09 b2_lsb b2 coefficient lsb 0x0a c12_msb c12 coefficient msb 0x0b c12_lsb c12 coefficient lsb 0x0c reserved* ? 0x0d reserved* ? 0x0e reserved* ? 0x0f reserved* ? 0x10 reserved ? 0x11 reserved ? 0x12 convert start pressure and temperature conversion *these registers are set to 0x00. these are reserved, and were previously utilized as coeffi cient values, c11 and c22, which were always 0x00. pressure, temperature and compensation coefficient specifications a0 b1 b2 c12 padc tadc total bits 16 16 16 14 10 10 sign bits 1 1 1 1 0 0 integer bits 12 2 1 0 10 10 fractional bits 3 13 14 13 0 0 dec pt zero pad 0 0 0 9 0 0
sensors 6 freescale semiconductor, inc. mpl115a1 example binary format definitions: a0 signed, integer bits = 12, fractional bits = 3 : coeff a0 = s i 11 i 10 i 9 i 8 i 7 i 6 i 5 i 4 i 3 i 2 i 1 i 0 . f 2 f 1 f 0 b1 signed, integer bits = 2, fractional bits = 13 : coeff b1 = s i 1 i 0 . f 12 f 11 f 10 f 9 f 8 f 7 f 6 f 5 f 4 f 3 f 2 f 1 f 0 b2 signed, integer bits = 1, fractional bits = 14 : coeff b2 = s i 0 . f 13 f 12 f 11 f 10 f 9 f 8 f 7 f 6 f 5 f 4 f 3 f 2 f 1 f 0 c12 signed, integer bits = 0, fractional bits = 13, dec pt zero pad = 9 : coeff c12 = s 0 . 000 000 000 f 12 f 11 f 10 f 9 f 8 f 7 f 6 f 5 f 4 f 3 f 2 f 1 f 0 padc unsigned, integer bits = 10 : padc u = i 9 i 8 i 7 i 6 i 5 i 4 i 3 i 2 i 1 i 0 tadc unsigned, integer bits =10 : tadc u = i 9 i 8 i 7 i 6 i 5 i 4 i 3 i 2 i 1 i 0 note: negative coefficients are coded in 2?s complement notation. 3.2 compensation the 10-bit compensated pressure output, pcomp, is calculated as follows: eqn. 1 where: padc is the 10-bit pressure adc output of the mpl115a tadc is the 10-bit temperatur e adc output of the mpl115a a0 is the pressure offset coefficient b1 is the pressure sensitivity coefficient b2 is the temperature coefficient of offset (tco) c12 is the temperature coefficient of sensitivity (tcs) pcomp will produce a value of 0 with an inpu t pressure of 50 kpa and will produce a full-scale value of 1023 with an input pres sure of 115 kpa. eqn. 2 3.3 evaluation sequence, arithmetic circuits the following is an example of the calculation for pcomp, the compensated pressure output. input values are in bold. c12x2 = c12 * tadc a1 = b1 + c12x2 a1x1 = a1 * padc y1 = a0 + a1x1 a2x2 = b2 * tadc pcomp = y1 + a2x2 this can be calculated as a succession of mult iply accumulates (macs) operations of the form y = a + b * x: pcomp a0 b1 c12 tadc ? + () padc b2 tadc ? + ? += pressure (kpa) p =comp 115 50 ? 1023 ---------------------- 50 + ? a b x y + x
sensors freescale semiconductor, inc. 7 mpl115a1 the polynomial can be evaluated ( equation 1 ) as a sequence of 3 macs: please refer to freescale application note an3785 for more detailed notes on implementation. 3.4 spi device read/write operations all device read/write operations are memory mapped. device acti ons e.g. ?start conversions? ar e controlled by writing to the appropriate memory address location. all memory address locations are 6-bit (see ta b l e 2 ). the 8-bit command word comprises: ? the most significant bit which is the read/write identifier which is '1' for read oper ations and '0' for write operations. ? the 6-bit address (from table 2 ); ? the least significant bit which is not used and is don't care (x). the device write commands are shown in ta b l e 3 . the actions taken by the part in resp onse to each command are as follows: table 3. spi write command command binary hex (1) 1. the command byte needs to be paired with a 0x00 as part of the spi exchange to complete the passing of start conversions . start conversions 0010010x 0x24 x = don?t care table 4. spi write command description command action taken start conversions wake main circuits. start clock. allow supply st abilization time. select pressure sensor input. apply positive sensor excitati on and perform a to d conversion. select temperature input. perform a to d conversion. load the pressure and temperature registers with the result. shut down main circuits and clock. pcomp a0 b1 c12 tadc ? + () padc b2 tadc ? + ? += b1 c12 tadc a0 b2 tadc padc a1 y1 y pcomp
sensors 8 freescale semiconductor, inc. mpl115a1 spi read operations are performed by sending the required address with a leading read bit set to ?1?. spi operations require that each byte be addressed individually. all da ta is transmitted most significant bit first. 3.5 spi timing ta b l e 6 and figure 3 describe the timing requir ements for the spi system. figure 3. spi timing diagram table 5. example spi read commands command binary hex (1) 1. the command byte needs to be paired with a 0x00 as part of the spi exchange to complete the passing of stated command. read pressure msb 1000000x 0x80 read pressure lsb 1000001x 0x82 read temperature msb 1000010x 0x84 read temperature lsb 1000011x 0x86 read coefficient data byte 1 1000100x 0x88 x = don?t care table 6. spi timing ref function symbol min max unit 1 operating frequency o f ? 8 mhz 2 sclk period tsclk 125 ? ns 3 sclk high time tclkh 62.5 ? ns 4 sclk low time tclkl 62.5 ? ns 5 enable lead time tscs 125 ? ns 6 enable lag time thcs 125 ? ns 7 data setup time tset 30 ? ns 8 data hold time thold 30 ? ns 9 data valid (after sclk low edge) tddly ? 32 ns 10 width cs high twcs 30 ? ns cs sclk din dout
sensors freescale semiconductor, inc. 9 mpl115a1 3.6 example of spi reading of coefficients these are mpl115a1 spi commands to read coefficients, execute pressure and temperature conversions, and to read pressure and temperature data. the sequence of the commands for the interaction is given as an example to operate the mpl115a1. utilizing this gathered data, an example of the calculating the compensated pressure reading is given in floating point notatio n. spi commands (simplified for communication) command to write ?convert pressure and temperature? = 0x24 command to read ?pressure adc high byte? = 0x80 command to read ?pressure adc low byte? = 0x82 command to read ?temperature adc high byte? = 0x84 command to read ?temperature adc low byte? = 0x86 command to read ?coefficient data byte 1 high byte? = 0x88 read coefficients: [cs=0], [0x88], [0x00], [0x8a], [0x00], [0x8c], [0x00], [0x8e], [0x00], [0x90], [0x00], [0x92], [0x00], [0x94], [0x00], [0x96], [0x00], [0x00], [cs=1] start pressure and temperature conversion, read raw pressure: [cs=0], [0x24], [0x00], [cs=1], [3 ms delay] [cs=0], [0x80], [0x00], [0x82], [0x00], [0x84], [0x00,] [0x86], [0x00], [0x00], [cs=1] note: extra [0x00] at the end of each sequence to output the last data byte on the slave side of the spi. figure 4. spi read coefficient datagram a0 coefficient msb = 0x41 a0 coefficient lsb = 0xdf a0 coefficient = 0x41df = 2107.875 b1 coefficient msb = 0xb0 b1 coefficient lsb = 0x28 b1 coefficient = 0xb028 = -2.49512 b2 coefficient msb = 0xbe b2 coefficient lsb = 0xad b2 coefficient = 0xbead = -1.02069 c12 coefficient msb = 0x38 c12 coefficient lsb = 0xcc c12 coefficient = 0x38cc = 0.00086665
sensors 10 freescale semiconductor, inc. mpl115a1 figure 5. spi start conversion datagram command to start pressure and temperature conversion, 0x24 figure 6. spi read results datagram 3.7 example of pressure compensated calc ulation in floating-point notation pressure compensation: pressure msb = 0x67 pressure lsb = 0xc0 pressure = 0x67c0 = 0110 0111 11 00 0000 = 415 adc counts temperature msb = 0x80 temperature lsb = 0x40 temperature = 0x8040 = 1000 0000 01 00 0000 = 513 adc counts a0 coefficient = 2107.875 b1 coefficient = -2.49512 b2 coefficient = -1.02069 c12 coefficient = 0.00086665 pressure = 415 adc counts temperature = 513 adc counts pcomp a0 b1 c12 tadc ? + () padc b2 tadc ? + ? +=
sensors freescale semiconductor, inc. 11 mpl115a1 using the evaluation sequence shown in section 3.3: 4 solder recommendations 1. use sac solder alloy (i.e., sn-ag-cu) with a melting point of about 217c. it is recommended to use sac305 (i.e., sn-3.0 wt.% ag-0.5 wt.% cu). 2. reflow ? ramp up rate: 2 to 3c/s. ? preheat flat (soak): 110 to 130s. ? reflow peak temperature: 250 c to 260c (depends on exact sac alloy composition). ? time above 217c: 40 to 90s (depends on board type, thermal mass of the board/quantities in the reflow). ? ramp down: 5 to 6c/s. ? using an inert reflow environment (with o 2 level about 5 to 15 ppm). note: the stress level and signal offset of the device also depen ds on the board type, board core material, board thickness and metal finishing of the board. c12x2 = c12 * tadc = 0.00086665 * 513 = 0.44459 a1 = b1 + c12x2 = -2.49512 + 0.44459 = -2.05052 a1x1 = a1 * padc = -2.05052 * 415 = -850.96785 y1 = a0 + a1x1 = 2107.875 + (-850.96785) = 1256.90715 a2x2 = b2 * tadc = -1.02069 * 513 = -523.61444 pcomp = y1 + a2x2 = 1256.90715 + (-523.61444) = 733.29270 pressure (kpa) p =comp 115 50 ? 1023 ---------------------- 50 + ? 733.29 = 115 50 ? 1023 ---------------------- 50 + ? 96.59kpa =
sensors 12 freescale semiconductor, inc. mpl115a1 5 handling recommendations it is recommended to handle the mpl115a pressure sensor with a vacuum pick and place tool. sharp objects utilized to move the mpl115a pressure sensor increase the possibility of da mage via a foreign object/tool into the small exposed port. the sensor die is sensitive to light exposure. direct light exposure through the port hole can lead to varied accuracy of press ure measurement. avoid such exposure to the port during normal operation. 6 soldering/landing pad information the lga package is compliant with the rohs standard. it is recommended to use a no-clean solder paste to reduce cleaning exposure to high pressure and chemical agents that can dam age or reduce life span of the pressure sensing element. figure 7. mpl115a1 recommended pcb landing pattern
sensors freescale semiconductor, inc. 13 mpl115a1 7 tape and reel specifications figure 8. lga (3 by 5) embossed carrier tape dimensions figure 9. device orientation in chip carrier (i) measured from centerline of sprocket hole to centerline of pocket. (ii) cumulative tolerance of 10 sprocket holes is 0.20. (iii) measured from centerline of sprocket hole to centerline of pocket. (iv) other material available. dimensions are in millimeters. ao 3.35 0.10 bo 5.35 0.10 ko 1.20 0.10 f 5.50 0.10 p1 8.00 0.10 w 12.00 0.10 pin 1 index area
sensors 14 freescale semiconductor, inc. mpl115a1 package dimensions case 2015-02 issue a lga package
sensors 15 freescale semiconductor, inc. mpl115a1 table 4. revision history revision number revision date description of changes 7 02/2013 ? changed example binary format definitions b1 signed from 7 to 13, added f 11 to coeff b1, b2 and c12 on page 6. ? removed mpl115a1t2 from ordering table.
document number: mpl115a1 rev. 7 02/2013 how to reach us: home page: freescale.com web support: freescale.com/support information in this document is provided solely to enable system and software implementers to use freescale products. there are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits based on the information in this document. freescale reserves the right to make changes without further notice to any products herein. freescale makes no warranty, representation, or guarantee regarding the suitability of its products for any particular purpose, nor does freescale assume any liability arising out of the app lication or use of an y product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. ?typical? parameters that may be provided in freescale data sheets and/or specifications can and do vary in differen t applications, and actual performance may vary over time. all operating parameters, including ?typicals,? must be validated for each customer application by customer?s technica l experts. freescale does not convey any license under its patent rights nor the rights of others. freescale sells products pursuant to standard terms and conditions of sale, which can be found at the following address: freescale.com/salestermsandconditions. freescale, the freescale logo, altivec, c-5, codetest, codewarrior, coldfire, c-ware, energy efficient solutions logo, kinetis, mobilegt, powerquicc, processor expert, qoriq, qorivva, starcore, symphony, and vortiqa are trademarks of freescale semiconductor, inc., reg. u.s. pat. & tm. off. airfast, beekit, beestack, coldfire+, corenet, flexis, magniv, mxc, platform in a package, qoriq qonverge, quicc engine, ready play, safeassure, smartmos , turbolink, vybrid, and xtrinsic are trademarks of freescale semiconductor, inc. all other product or service names are the property of their respective owners. ? 2011 freescale semiconductor, inc.

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