SCA1000-N1000070-PCB

SCA1000 Series Data Sheet SCA1000-N1000070 2-AXIS HIGH PERFORMANCE ANALOG ACCELEROMETER Features Applications       Measurement range ±4g Measurement bandwidth 115 Hz Low noise ratiometric analog voltage outputs Excellent bias stability over temperature and time Digital SPI temperature output Comprehensive failure detection features o True self test by deflecting the sensing element's proof mass with electrostatic force. o Continuous sensing element interconnection failure check. o Continuous memory parity check.  RoHS and lead free soldering process compliant  Robust design, high shock durability (20000g) SCA1000-N1000070 is targeted to inertial sensing applications with high stability and tough environmental requirements. Typical application include  IMU, AHRS  Avionics  UAV  Navigation and guidance instruments  Platform stabilization  Vibration monitoring  Oil & Gas surveying and drilling  Train and Rail industry General Description The SCA1000-N1000070 is a 3D-MEMS-based dual axis accelerometer that enables tactical grade performance for Inertial Measurement Units (IMUs) operating in tough environmental conditions. The measuring axes of the sensor are parallel to the mounting plane and orthogonal to each other. Wide measurement range and bandwidth, low repeatable temperature behavior, low output noise, together with a very robust sensing element and packaging design, make the SCA1000-N1000070 the ideal choice for challenging inertial sensing applications. 12 VDD Sensing element 1 Signal conditioning and filtering 11 OUT_1 A/D conversion 10 ST_1 9 ST_2 Self test 1 Self test 2 EEPROM calibration memory Temperature Sensor 1 SCK SPI interface 3 MISO 4 MOSI 7 CSB Sensing element 2 Signal conditioning and filtering 5 OUT_2 6 GND Figure 1. Functional block diagram Murata Electronics Oy www.murata.com Subject to changes Doc. nr. 8261800 1/14 Rev.A SCA1000 Series TABLE OF CONTENTS SCA1000-N1000070 2-Axis HIGH PERFORMANCE ANALOG ACCELEROMETER ..............1 Table of Contents......................................................................................................................2 1 Electrical Specifications .....................................................................................................3 1.1 Absolute Maximum Ratings ................................................................................................... 3 1.2 Performance Characteristics.................................................................................................. 3 1.3 Parameter ................................................................................................................................ 3 1.4 Electrical Characteristics ....................................................................................................... 4 1.5 SPI Interface DC Characteristics............................................................................................ 4 1.6 SPI Interface AC Characteristics............................................................................................ 4 1.7 SPI Interface Timing Specifications ....................................................................................... 5 1.8 Electrical Connection.............................................................................................................. 6 2 Functional Description .......................................................................................................7 2.1 Measuring Directions .............................................................................................................. 7 2.2 Ratiometric Output .................................................................................................................. 7 2.3 SPI Serial Interface.................................................................................................................. 7 2.4 Self Test and Failure Detection Modes ................................................................................ 10 2.5 Temperature Measurement .................................................................................................. 11 3 Application Information ....................................................................................................12 3.1 Recommended Circuit Diagrams and Printed Circuit Board Layouts ............................... 12 3.2 Recommended Printed Circuit Board Footprint ................................................................. 13 4 Mechanical Specifications and Reflow Soldering ..........................................................13 4.1 Mechanical Specifications .................................................................................................... 13 4.2 Reflow Soldering ................................................................................................................... 14 Murata Electronics Oy www.murata.com Subject to changes Doc. nr. 82 1566 00 2/14 Rev.A SCA1000 Series 1 Electrical Specifications The product version specific performance specifications are listed in the table SCA1000 performance characteristics below. Vdd=5.00V and ambient temperature unless otherwise specified. 1.1 Absolute Maximum Ratings Supply voltage (VDD) Voltage at input / output pins Storage temperature Operating temperature Mechanical shock 1.2 -0.3 V to +5.5V -0.3V to (VDD + 0.3V) -55°C to +125°C -40°C to +125°C Drop from 1 meter onto a concrete surface (20000g). Powered or non-powered Performance Characteristics 1.3 Parameter Measuring range Frequency response Offset (Output at 0g) Offset Digital Output Offset Calibration error Offset Temperature Dependency Sensitivity Sensitivity Digital Output Sensitivity Calibration error Sensitivity Temperature Dependency Linearity error Condition Min Typical Max (1 Units Nominal –3dB LP Ratiometric output -4 60 Vdd/2 115 +4 170 Vdd/2 -40…+125°C -20 50 g Hz V LSB mg mg 1024 -40…+125°C -2 -2.5 ±4g range ±4g range From DC...100Hz Ratiometric error Cross-axis sensitivity Vdd = 4.75...5.25V Max. Murata Electronics Oy www.murata.com 20 50 0.55 226 Digital Output Resolution Output Noise Density Note 1. (1 +2 +2 80 160 11 95 -2 -3.5 V/g LSB / g % % mg mg Bits 11 120 g / Hz +2 +3.5 % % Min/Max values are +/-3 sigma of test population Subject to changes Doc. nr. 82 1566 00 3/14 Rev.A SCA1000 Series 1.4 Electrical Characteristics Parameter Supply voltage Vdd Current consumption Operating temperature Analog resistive output load Analog capacitive output load Start-up delay 1.5 Min. Typ Max. Units 4.75 5.0 4 5.25 5 V mA +125 °C Vdd = 5 V; No load -40 Vout to Vdd or GND 10 kΩ Vout to Vdd or GND 20 nF Reset and parity check 10 ms SPI Interface DC Characteristics Parameter Conditions Symbol Min Typ. Max Unit VIN = 0 V IPU VIH VIL VHYST CIN 13 4 -0.3 22 35 Vdd+0.3 1 A V V V pF Input terminal MOSI, SCK Pull down current VIN = 5 V Input high voltage Input low voltage Hysteresis IPD VIH VIL VHYST 9 4 -0.3 29 Vdd+0.3 1 0.23*Vdd A V V V Input capacitance CIN 2 pF Output terminal MISO Output high voltage I > -1mA VOH Output low voltage Tri-state leakage VOL ILEAK Input terminal CSB Pull up current Input high voltage Input low voltage Hysteresis Input capacitance 1.6 Condition I < 1 mA 0 < VMISO < Vdd 0.23*Vdd 2 17 Vdd0.5 V 5 0.5 100 V pA SPI Interface AC Characteristics Parameter Condition Output load SPI clock frequency Internal A/D conversion time Data transfer time @500kHz Murata Electronics Oy www.murata.com @500kHz Subject to changes Doc. nr. 82 1566 00 Min. Typ. 150 38 Max. Units 1 500 nF kHz s s 4/14 Rev.A SCA1000 Series 1.7 SPI Interface Timing Specifications Parameter Terminal CSB, SCK Time from CSB (10%) To SCK (90%) Time from SCK (10%) To CSB (90%) Terminal SCK SCK low time Conditions Symbol Min. TLS1 120 ns TLS2 120 ns TCL 1 s TCH 1 s TSET 30 ns THOL 30 ns Load capacitance at MISO < 15 pF Load capacitance at MISO < 15 pF TVAL1 10 100 ns TLZ 10 100 ns Load capacitance at MISO < 15 pF TVAL2 100 ns Load capacitance at MISO < 2 nF Load capacitance at MISO < 2 nF SCK high time Terminal MOSI, SCK Time from changing MOSI (10%, 90%) to SCK (90%). Data setup time Time from SCK (90%) to changing MOSI (10%,90%). Data hold time Terminal MISO, CSB Time from CSB (10%) to stable MISO (10%, 90%). Time from CSB (90%) to high impedance state of MISO. Terminal MISO, SCK Time from SCK (10%) to stable MISO (10%, 90%). Terminal CSB Time between SPI cycles, CSB at high level (90%) When using SPI commands RDAX, RDAY, and RWTR: Time between SPI cycles, CSB at high level (90%) TLS1 TCH Typ. Max. Unit TLH 15 s TLH 150 s TCL TLS2 TLH CSB SCK THOL MOSI MSB in TVAL1 MISO TSET DATA in LSB in TVAL2 MSB out TLZ DATA out LSB out Figure 2. Timing diagram for SPI communication Murata Electronics Oy www.murata.com Subject to changes Doc. nr. 82 1566 00 5/14 Rev.A SCA1000 Series 1.8 Electrical Connection If the SPI interface is not used SCK (pin1), MISO (pin3), MOSI (pin4) and CSB (pin7) must be left floating. Self-test can be activated applying logic “1” (positive supply voltage level) to ST_1 or ST_2 pins (pins 10 or 9). Self-test must not be activated for both channels at the same time. If ST feature is not used pins 9 and 10 must be left floating or connected to GND. Acceleration signals are provided from pins OUT_1 and OUT_2. SCK SCK 1 Ext_C_1 VDD 12 VDD OUT_1 11 OUT_1 2 MISO 3 MISO 10 ST_1/Test_in ST_1 MOSI 4 MOSI 9 ST_2 ST_2 OUT_2 5 OUT_2 8 Ext_C_2 VSS 6 GND 7 CSB CSB Figure 3. SCA1000 electrical connection No. 1 2 3 4 5 6 7 8 9 10 11 12 Murata Electronics Oy www.murata.com Node SCK NC MISO MOSI Out_2 GND CSB NC ST_2 ST_1 Out_1 VDD I/O Input Input Output Input Output Supply Input Input Input Input Output Supply Description Serial clock No connect, left floating Master in slave out; data output Master out slave in; data input Y axis Output (Ch 2) Ground Chip select (active low) No connect, left floating Self test input for Ch 2 Self test input for Ch 1 X axis Output (Ch 1) Positive supply voltage (+5V DC) Subject to changes Doc. nr. 82 1566 00 6/14 Rev.A SCA1000 Series 2 2.1 Functional Description Measuring Directions X-axis Y-axis VOUT > VOUT =2.5V > VOUT Figure 4. The measuring directions of the SCA1000 2.2 Ratiometric Output Ratiometric output means that the zero offset point and sensitivity of the sensor are proportional to the supply voltage. If the SCA1000 supply voltage is fluctuating the SCA1000 output will also vary. When the same reference voltage for both the SCA1000 sensor and the measuring part (A/Dconverter) is used, the error caused by reference voltage variation is automatically compensated for. 2.3 SPI Serial Interface A Serial Peripheral Interface (SPI) system consists of one master device and one or more slave devices. The master is defined as a micro controller providing the SPI clock and the slave as any integrated circuit receiving the SPI clock from the master. The ASIC in Murata Electronics’ products always operates as a slave device in master-slave operation mode. The SPI has a 4-wire synchronous serial interface. Data communication is enabled by a low active Slave Select or Chip Select wire (CSB). Data is transmitted by a 3-wire interface consisting of wires for serial data input (MOSI), serial data output (MISO) and serial clock (SCK). Murata Electronics Oy www.murata.com Subject to changes Doc. nr. 82 1566 00 7/14 Rev.A SCA1000 Series MASTER MICROCONTROLLER SLAVE DATA OUT (MOSI) SI DATA IN (MISO) SO SERIAL CLOCK (SCK) SCK SS0 CS SS1 SI SS2 SO SS3 SCK CS SI SO SCK CS SI SO SCK CS Figure 5. Typical SPI connection The SPI interface in Murata products is designed to support any micro controller that uses SPI bus. Communication can be carried out by either a software or hardware based SPI. Please note that in the case of hardware based SPI, the received acceleration data is 11 bits. The data transfer uses the following 4-wire interface: MOSI MISO SCK CSB master out slave in master in slave out serial clock chip select (low active) µP → SCA1000 SCA1000 → µP µP → SCA1000 µP → SCA1000 Each transmission starts with a falling edge of CSB and ends with the rising edge. During transmission, commands and data are controlled by SCK and CSB according to the following rules:           Murata Electronics Oy www.murata.com commands and data are shifted; MSB first, LSB last each output data/status bits are shifted out on the falling edge of SCK (MISO line) each bit is sampled on the rising edge of SCK (MOSI line) after the device is selected with the falling edge of CSB, an 8-bit command is received. The command defines the operations to be performed the rising edge of CSB ends all data transfer and resets internal counter and command register if an invalid command is received, no data is shifted into the chip and the MISO remains in high impedance state until the falling edge of CSB. This reinitializes the serial communication. data transfer to MOSI continues immediately after receiving the command in all cases where data is to be written to SCA1000’s internal registers data transfer out from MISO starts with the falling edge of SCK immediately after the last bit of the SPI command is sampled in on the rising edge of SCK maximum SPI clock frequency is 500kHz maximum data transfer speed for RDAX and RDAY is 5300 samples per sec / channel Subject to changes Doc. nr. 82 1566 00 8/14 Rev.A SCA1000 Series SPI command can be either an individual command or a combination of command and data. In the case of combined command and data, the input data follows uninterruptedly the SPI command and the output data is shifted out parallel with the input data. The SPI interface uses an 8-bit instruction (or command) register. The list of commands is given in Table below. Command name MEAS RWTR STX STY RDAX RDAY Command format 00000000 00001000 00001110 00001111 00010000 00010001 Description: Measure mode (normal operation mode after power on) Read temperature data register Activate Self test for X-channel Activate Self test for Y-channel Read X-channel acceleration Read Y-channel acceleration Measure mode (MEAS) is standard operation mode after power-up. During normal operation, the MEAS command is the exit command from Self test. Read temperature data register (RWTR) reads temperature data register during normal operation without affecting the operation. The temperature data register is updated every 150 µs. The load operation is disabled whenever the CSB signal is low, hence CSB must stay high at least 150 µs prior to the RWTR command in order to guarantee correct data. The data transfer is presented in Figure 10 below. The data is transferred MSB first. In normal operation, it does not matter what data is written into temperature data register during the RWTR command and hence writing all zeros is recommended. Figure 1. Command and 8 bit temperature data transmission over the SPI Self test for X-channel (STX) activates the self test function for the X-channel (Channel 1). The internal charge pump is activated and a high voltage is applied to the X-channel acceleration sensor element electrode. This causes the electrostatic force that deflects the beam of the sensing element and simulates the acceleration to the positive direction. The self-test is de-activated by giving the MEAS command. The self test function must not be activated for both channels at the same time. Self test for Y-channel (STY) activates the self test function for the Y-channel (Channel 2). The internal charge pump is activated and a high voltage is applied to the Y-channel acceleration sensor element electrode. Read X-channel acceleration (RDAX) accesses the AD converted X-channel (Channel 1) acceleration signal stored in acceleration data register X. Murata Electronics Oy www.murata.com Subject to changes Doc. nr. 82 1566 00 9/14 Rev.A SCA1000 Series Read Y-channel acceleration (RDAY) accesses the AD converted Y-channel (Channel 2) acceleration signal stored in acceleration data register Y. During normal operation, acceleration data registers are reloaded every 150 µs. The load operation is disabled whenever the CSB signal is low, hence CSB must stay high at least 150 µs prior the RDAX command in order to guarantee correct data. Data output is an 11-bit digital word that is fed out MSB first and LSB last. Figure 6. Command and 11 bit acceleration data transmission over the SPI 2.4 Self Test and Failure Detection Modes To ensure reliable measurement results the SCA1000 has continuous interconnection failure and calibration memory validity detection. A detected failure forces the output signal close to power supply ground or VDD level, outside the normal output range. The normal output ranges are: analog 0.25-4.75 V (@Vdd=5V) and SPI 102...1945 counts. The calibration memory validity is verified by continuously 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 parity error is detected after re-loading data both analog output voltages are forced to go close to ground level (