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SCA720-D01 murata electronics oy 1/12 www.muratamems.fi doc.nr. 82171500 rev.a data sheet SCA720-D01 single axis accelerometer with analog in terface the sca720 accelerometer consists of a silicon bulk micro machined sensing element chip and a signal conditioning asic. the chips are mounted on a pre-m olded package and wire bonded to appropriate contac ts. the sensing element and asic are protected with sil icone gel and lid. the sensor has 12 smd legs (gull -wing type). features ? single +5 v supply ? current consumption 2.5 ma typical ? ratiometric output in relation to supply voltage (vdd = 4.75 v...5.25 v) ? enhanced failure detection features o digitally activated, true self-test by proof mass deflection using electrostatic force o memory parity check during power up, and self-test cycle. o built in connection failure detection ? digitally activated, true self-test by proof mass deflection using electrostatic force ? wide load drive capability (max. 20 nf) ? true dc response ? full traceability information in 2d-matrix on the lid ? qualified according to aec-q100 standard applications sca720 product family is targeted to automotive applications with high stability and reliability requirements. automotive target applications are: ? electrically controlled suspension ? engine anti-vibration figure 1. functional block diagram. asic eeprom for calibration constants (32 bit, pari ty check ) measurem en t circuitry gain & filtering 4 programming lines for factory use only gnd vout sensing element digital self test input 5v supply
SCA720-D01 murata electronics oy 2/13 www.muratamems.fi doc. nr. 82171500 rev.a table of contents SCA720-D01 single axis accelerometer with analog in terface ........................................... 1 f eatures .................................................. ................................................... ............................... 1 a pplications .................................................. ................................................... ......................... 1 t able of c ontents .................................................. ................................................... ............... 2 1. electrical specifications ......................... ................................................... ................ 3 1.1. a bsolute m aximum r atings .................................................. .......................................... 3 1.2. p erformance c haracteristics .................................................. ................................... 3 1.3. o ffset and sensitivity calibration .................................................. .............................. 4 1.4. e rror calculations .................................................. ................................................... .. 4 1.5. s upply voltage .................................................. ................................................... .......... 5 1.6. e lectrical c onnection .................................................. ................................................ 6 1.7. l imiter function ................................................... ................................................... ........ 8 2. functional description ............................ ................................................... ............... 9 2.1. m easuring directions .................................................. .................................................. 9 2.2. v oltage to acceleration conversion .................................................. ........................ 9 2.3. r atiometric o utput .................................................. ................................................... .. 9 2.4. s elftest and failure detection modes .................................................. ....................... 9 3. application information ........................... ................................................... .............. 11 3.1. h ousing dimensions and recommended pcb layout .................................................. 11 3.2. r eflow soldering .................................................. ................................................... ... 12
SCA720-D01 murata electronics oy 3/13 www.muratamems.fi doc. nr. 82171500 rev.a 1. electrical specifications 1.1. absolute maximum ratings parameter value units acceleration (powered or non-powered) 20 000 (1 g supply voltage ?0.3 to +7.0 v voltage at input / output pins ?0.3 to v dd + 0.3 v esd hbm (human body model) 2 kv esd cdm (charged device model) 500 middle pins 750 corner pins v temperature range (storage) ?50 to +125 c temperature range (operating) ?40 to +125 c 1 equals to drop from 1 meter on a concrete surface. 1.2. performance characteristics v dd = 5.00 v and ambient temperature unless otherwise specified. kpc a ) parameter condition min. typ m ax. units measuring range nominal -1.11 +3.11 g supply voltage vdd 4.75 5.0 5.25 v current consumption vdd = 5 v; no load 2.5 4.0 ma operating temperature ?40 +125 c resistive output load vout to vdd or vss 20 k capacitive load vout to vdd or vss 20 nf min. output voltage; vdd = 5 v 20k from vout to vdd 0 0.25 v max. output voltage; vdd = 5 v 20k from vout to vss 4 .75 5.00 v linear output voltage range limiter function enabled 0.5 4.5 v offset (output at +1 g) @ room temperature vd d/2 v sensitivity @ room temperature 0.1875 vdd ( 0.9375) v/g offset error (output at +1 g) ?40 c...125 c -1 37 0 +137 mg sensitivity error ?40 c...125 c ?3 0 +3 % typical non-linearity within the measuring range ?60 +60 mg amplitude response ?3 db b) 68 115 170 hz ratiometric error vdd = 4.75 v...5.25 v ?2 +2 % cross-axis sensitivity @ room temperature 3. 9 % output noise from dc...4 khz 5 mv rms start-up delay reset and parity check 10 ms self test pull down resistor (internal) 44 62 80 k a) cc= critical characteristics. must be 100% monitore d during production sc= significant characteristic. the process capabil ity (cpk) must be better than 1.33, which allows sa mple based testing. if process is not capable the part will be 100% tested b) output has true dc response
SCA720-D01 murata electronics oy 4/13 www.muratamems.fi doc. nr. 82171500 rev.a 1.3. offset and sensitivity calibration vout offset is calibrated in 0g position: ( ) g v offset out 1 + = [v] nominal offset is vdd/2: 2 dd nom v offset = [v] sensitivity is calibrated as: ( ) ( ) g g v g v y sensitivit out out 2 1 1 ? ? + = [v/g] nominal sensitivity is: 9375 .0 = nom y sensitivit [v/g] 1.4. error calculations total error is the allowed maximum error, which inc lude partial error sources. total error over lifetime is specified as a sum of offset and sensit ivity errors: error y sensitivit error offset error total _ _ _ + = [mg] offset error is specified as: ( ) y sensitivit v g vout error offset dd 2 1 _ ? + = [mg] sensitivity error percent is specified as: ( ) ( ) [ ] % 100 2 1 1 % _ ? ? ? + = nom nom y sensitivit y sensitivit g g vout g vout error y sensitivit sensitivity error is specified as: ( ) [ ] y sensitivit error y sensitivit g vout vout error y sensitivit % _ 1 _ + ? = [mg]
SCA720-D01 murata electronics oy 5/13 www.muratamems.fi doc. nr. 82171500 rev.a 1.5. suppl y voltage usage of external 100 nf power supply bypass capaci tor is recommended. asic start-up should be tolerant to noise between v dd and gnd. recommended power-up ramp is presented below. parameter min max t 1 t 0 + 0.1 s t 2 t 0 + 100 s v 1 ?0.3 v 0.5 v v 2 4.5 v 5.5 v supply voltage ramp at startup. figure 2. v dd start-up sequence. t 0 t 1 t 2 supply voltage v 2 t v 1
SCA720-D01 murata electronics oy 6/13 www.muratamems.fi doc. nr. 82171500 rev.a 1.6. electrical connection the following is minimum requirement for electrical interface to the sca720. if over-voltage or reverse polarity protection is needed, please conta ct murata electronics oy for application information. usage of external minimum 100 nf power supply bypas s capacitor is recommended. maximum rise time of v dd is 100 us. if self-test (pin 9) is not used it should be left floating. pins 1, 2, 3, 4, 6, 7 and 8 are left floating. if the self test is used if the self test is not used figure 3. electrical connection of sca720 component. 1 2 3 4 5 6 12 11 10 9 8 7 clk c1 nc mode gnd nc vdd vout egnd st pgm nc sca720 c1 100 nf vdd vout 1 2 3 4 5 6 12 11 10 9 8 7 clk c1 nc mode gnd nc vdd vout egnd st pgm nc sca720 c1 100 nf vdd vout st
SCA720-D01 murata electronics oy 7/13 www.muratamems.fi doc. nr. 82171500 rev.a no. name function connect 1 reserved not used not connected 2 clk data shift clock (factory only) not connected 3 c1 (factory only) not connected 4 mode mode control input (factory only) not connec ted 5 gnd negative supply voltage (v ss ) ground 6 reserved not used not connected 7 reserved not used not connected 8 pgm programming voltage (factory only) not connec ted 9 st self test control float when not used 10 vout sensor output voltage next stage input 11 vdd positive supply voltage (v dd ) v dd (+5 v) 12 egnd emc ground (lid grounding) ground 1 2 3 4 5 6 12 11 10 9 8 7
SCA720-D01 murata electronics oy 8/13 www.muratamems.fi doc. nr. 82171500 rev.a 1.7. limiter function the table below defines the limiter function. parameter condition min max unit limiter cutoff voltage low voltage limit high voltage limit 0.05 vdd 0.90 vdd 0.10 vdd 0.95 vdd v v min output voltage limiter enabled, vdd = 5 v 0.25 v max output voltage limiter enabled, vdd = 5 v 4.75 v linear range limiter enabled, vdd = 5 v 0.5 4.5 v 0.0 0.1 0.2 0.4 0.3 0.5 0.6 0.7 0.9 0.8 1.0 min max acceleration output as ratio to vdd figure 4. limiter function. limiter function limits the output voltage between specified upper and lower limit. in normal operation (v dd = 5.0 v), when limiter is enabled, the output volt age is valid between 0.5 v?4.5 v. limiting activates between 0.25 v?0.5 v and 4.5 v?4 .75 v. only failures drive output voltage beyond cutoff voltages.
SCA720-D01 murata electronics oy 9/13 www.muratamems.fi doc. nr. 82171500 rev.a 2. functional description 2.1. measuring directions 2.2. voltage to acceleration conversion analog output can be transferred to acceleration us ing the following equation for conversion: ( ) y sensitivit g v v on accelerati out out 0 ? = [g] where: v out (0g) = nominal output of the device at 0g position with 5 v supply voltage (ratiometric output), sensitivity is the sensitivity of the devi ce and v out is the output of the sensor. 2.3. ratiometric output ratiometric output means that the zero offset point and sensitivity of the sensor are proportional to the supply voltage. if the sca720 supply voltage is fluctuating the sca720 output will also vary. when the same reference voltage for both the sca720 sensor and the measuring part (a/d- converter) is used, the error caused by reference v oltage variation is automatically compensated for. 2.4. selftest and failure detection modes to ensure reliable measurement results the sca720 h as continuous interconnection failure and calibration memory validity detection. a detected f ailure forces the output signal close to power supply ground or vdd level, outside the normal outp ut range. the calibration memory validity is verified by cont inuously running parity check for the control register memory content. in the case where a parity error is detected, the control register is automatically re-loaded from the eeprom. if a new p arity error is detected after re-loading data analog output voltage is forced to go close to grou nd level (<0.25 v). the sca720 also includes a separate self test mode. the true self test simulates acceleration, or deceleration, using an electrostatic force. the ele ctrostatic force simulates acceleration that is hig h enough to deflect the proof mass to the extreme pos itive position, and this causes the output signal to go to the maximum value. the self test function is activated by a separate on-off command on the self test input. 0 g position v out ,nom = 1. 5625 v ? 1 g position v out ,nom = 0. 625 v +1 g position v out,nom = 2.5 v
SCA720-D01 murata electronics oy 10/13 www.muratamems.fi doc. nr. 82171500 rev.a the self-test generates an electrostatic force, def lecting the sensing element?s proof mass, thus checking the complete signal path. the true self te st performs following checks: ? sensing element movement check ? asic signal path check ? pcb signal path check ? micro controller a/d and signal path check the created deflection can be seen in analogue outp ut. self test can be activated applying logic?1? (positive supply voltage level) to st pin (pin 9) o f sca720. the self test input high voltage level is 4 ? vdd+0.3 v and input low voltage level is 0.3 ? 1 v. figure 7. self test wave forms. v1 = initial output voltage before the self test fu nction is activated. v2 = output voltage during the self test function. v3 = output voltage after the self test function ha s been de-activated and after stabilization time please note that the error band specified for v3 is to guarantee that the output is within 5% of the initial value after the specified stabilization tim e. after a longer time (max. 1 second) v1=v3. t1 = pulse length for self test activation t2 = saturation delay t3 = recovery time t4 = stabilization time =t2+t3 t5 = rise time during self test. t1 [ms] t2 [ms] t3 [ms] t4 [ms] t5 [ms] v2: v3: 10-100 typ. 20 typ. 50 typ. 70 typ. 10 min 0.95 *vdd (4.75v @vdd=5v) 0.95*v1- 1.05*v1 self test characteristics. vout 5v 0 v t ime [ ms ] t1 t2 t3 t4 v1 v2 v3 st pin voltage 0 v 5 v t5
SCA720-D01 murata electronics oy 11/13 www.muratamems.fi doc. nr. 82171500 rev.a 3. application information the sca720 should be powered from a well regulated 5 v dc power supply. coupling of digital noise to the power supply line should be minimized. 100nf filtering capacitor between vdd pin 11 and gnd plane must be used. if regulator is placed far from component for example other pcb it is recommend adding more capacitance between vdd an d gnd to ensure current drive capability of the system. for example 470 pf and 1uf capacitor can be used. the sca720 has a ratiometric output. to get the bes t performance use the same reference voltage for both the sca720 and analog/digital conv erter. locate the 100nf power supply filtering capacitor c lose to vdd pin 11. use as short a trace length as possible. connect the other end of capacitor dir ectly to the ground plane. connect the gnd pin 5 to underlying ground plane. use as wide ground an d power supply planes as possible. avoid narrow power supply or gnd connection strips on pcb . 3.1. housing dimensions and recommended pcb la yout figure 8 . housing dimensions and recommended pcb layout [mm] . notes: ? it is important that the part is parallel to the p cb plane and that there is no angular alignment error from intended measuring direction during asse mbly process. ? 1 mounting alignment error will increase the cros s-axis sensitivity by 1.7% ? 1 mounting alignment error will change the output by 17 mg ? wave soldering is not recommended ? ultrasonic cleaning is not allowed ? a supply voltage by-pass capacitor (> 100 nf) is r ecommended
SCA720-D01 murata electronics oy 12/13 www.muratamems.fi doc. nr. 82171500 rev.a 3.2. reflow soldering the sca720 is suitable for sn-pb eutectic and pb- f ree soldering process and mounting with normal smd pick-and-place equipment. recommended bo dy temperature profile during reflow soldering: figure 10. recommended body temperature profile during reflow soldering. ref. ipc/jedec j-std-020d. profile feature sn-pb eutectic assembly pb-free assembly average ramp-up rate (t l to t p ) 3 c/second max. 3 c/second max. preheat - temperature min (t smin ) - temperature max (t smax ) - time (min to max) (ts) 100 c 150 c 60-120 seconds 150 c 200 c 60-180 seconds tsmax to t l - ramp up rate 3c/second max time maintained above: - temperature (t l ) - time (t l ) 183 c 60-150 seconds 217 c 60-150 seconds peak temperature (t p ) 240 +0/?5 c 250 +0/?5 c time within 5 c of actual peak temperature (t p ) 10-30 seconds 20-40 seconds ramp-down rate 6 c/second max 6 c/second max time 25 c to peak temperature 6 minutes max 8 minu tes max the moisture sensitivity level of the part is 3 acc ording to the ipc/jedec j-std-020d. the part should be delivered in a dry pack. the manufac turing floor time (out of bag) in the customer?s end is 168 hours.
SCA720-D01 murata electronics oy 13/13 www.muratamems.fi doc. nr. 82171500 rev.a notes: ? preheating time and temperatures according to guid ance from solder paste manufacturer. ? it is important that the part is parallel to the p cb plane and that there is no angular alignment error from intended measuring direction d uring assembly process. ? wave soldering is not recommended. ? ultrasonic cleaning is not allowed . the sensing element may be damaged by an ultrasonic cleaning process the moisture sensitivity level of the part is 3 acc ording to the ipc/jedec j-std- 020b. the part should be delivered in a dry pack. t he manufacturing floor time (out of bag) in the customer?s end is 168 hours. maximum so ldering temperature is 250 c/40 sec. rework after the initial soldering process is not r ecommended. rework can cause heat build-up to the leg and this heat build-up will cau se the housing material to get soft thus allowing the leg to move. the movement can cau se bond wire disconnection inside the part.

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