SCA103T

SCA103T VTI | Alldatasheet

Document overview

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Technical content

Features

• Measuring ranges ±15° SCA103T-D04 and ± 30° SCA103T-D05
• 0.001° resolution (10 Hz BW, analog output)
• Sensing element controlled over damped frequency response (-3dB 18Hz)
• Robust design, high shock durability (20000g)
• Excellent stability over temperature and time
• Common mode error and noise reduction using the differential measurement principle
• Single +5 V supply
• Ratiometric analog voltage outputs
• Digital SPI inclination and temperature output
• Comprehensive failure detection features o True self test by deflecting the sensing elements’ proof mass by electrostatic force. o Continuous sensing element interconnection failure check. o Continuous memory parity check.
• RoHS compliant
• Compatible with Pb-free reflow solder process

Applications

• Platform leveling and stabilization
• Rotating laser levels
• Leveling instruments
• Construction levels

Figure 1. Functional block diagram

VTI Technologies Oy S ubject to changes 2/19 TABLE OF CONTENTS

VTI Technologies Oy S ubject to changes 3/19

1 Electrical Specifications

The SCA103T product family cons ists of two versions, the SCA1 03T-D04 and the SCA103T-D05, that differ in measurement range. The specific performance specifications related to each version are listed in the table “SCA103T pe rformance characteristics” below. All other specifications are common to both versions. The supply voltage is Vdd=5.00V and ambient temperature unless otherwise specified. Parameters marked as D are valid when measured in differentia l mode using an external differential amplifier. Parameters marked with S are for a single measurement channel. The performance of the selected amplifier may have an effect on some parameters. The differential signal is determined as Out_diff = Out1 – Out2.

1.1 Absolute Maximum Ratings

Supply voltage (VDD) Voltage at input / output pins Storage temperature Operating temperature Mechanical shock -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 metre onto a concrete surface (20000g). Powered or non-powered

1.2 Performance Characteristics

Parameter D/S Condition SCA103T -D04 SCA103T -D05 Units Measuring range D Nominal ±15 ±0.26 ±30 ±0.5 g Frequency response S –3dB LP (1 8-28 8-28 Hz Offset (Output at 0g) S Ratiometric output Vdd/2 Vdd/2 V Offset calibration error S ±0.057 ±0.11 ° Offset Digital Output S 1024 1024 LSB Sensitivity D between 0…1° (2 280 140 V/g mV/° Sensitivity calibration error S ±0.5 ±0.5 % Sensitivity Digital Output D 6554 3277 LSB / g D -25…85°C (typical) ±0.002 ±0.002 °/°C Offset temperature dependency -40…125°C (max) ±0.29 ±0.29 ° Typical non-linearity D Measuring range ±0.057 ±0.11 ° Digital output resolution D between 0…1° (2 0.009 0.017 Bits ° / LSB Analog output resolution D Bandwidth 10 Hz (3 0.0013 0.0013 ° Cross-axis sensitivity S Max. 4 4 % Long term stability (4 D <0.004 <0.004 ° Note 1. The frequency response is determined by the sensing element’s internal gas damping. Note 2. The angle output has SIN curve relations hip to voltage output - refer to chapter 2.2 Note 3. Resolution = Noise density * √(bandwidth) Note 4. Power continuously connected (@ 23°C)

VTI Technologies Oy S ubject to changes 4/19

1.3 Electrical Characteristics

Parameter Condition Min. Typ Max. Units Supply voltage Vdd 4.75 5.0 5.25 V Current consumption Vdd = 5 V; No load 4 5 mA Operating temperature -40 +125 °C Analog resistive output load Vout to Vdd or GND 10 kOhm Analog capacitive output load Vout to Vdd or GND 20 nF Start-up delay Reset and parity check 10 ms

1.4 SPI Interface DC Characteristics

Parameter Conditions Symbol Min Typ Max Unit Input terminal CSB Pull up current V IN = 0 V I PU 13 22 35 µA Input high voltage VIH 4 Vdd+0.3 V Input low voltage V IL -0.3 1 V Hysteresis VHYST 0.23*Vdd V Input capacitance C IN 2 pF Input terminal MOSI, SCK Pull down current V IN = 5 V I PD 9 17 29 µA Input high voltage VIH 4 Vdd+0.3 V Input low voltage V IL -0.3 1 V Hysteresis VHYST 0.23*Vdd V Input capacitance C IN 2 pF Output terminal MISO Output high voltage I > -1mA V OH Vdd- 0.5 V Output low voltage I < 1 mA VOL 0.5 V Tristate leakage 0 < V MISO < Vdd ILEAK 5 100 pA

1.5 SPI Interface AC Characteristics

Parameter Condition Min. Typ. Max. Units Output load @500kHz 1 nF SPI clock frequency 500 kHz Internal A/D conversion time 150 µs Data transfer time @500kHz 38 µs

1.6 SPI Interface Ti ming Specifications

Figure 2. Timing diagram for SPI communication

1.7 Electrical Connection

provided from pins OUT_1 and OUT_2. Figure 3. SCA103T electrical connection

1 SCK Input Serial clock

2 NC Input No connect, left floating

3 MISO Output Master in slave out; data output

4 MOSI Input Master out slave in; data input

5 Out_2 Output Output 2 (Ch 2)

6 GND Supply Ground

7 CSB Input Chip select (active low)

8 NC Input No connect, left floating

9 ST_2 Input Self test input for Ch 2

10 ST_1 Input Self test input for Ch 1

11 Out_1 Output Output 1(Ch 1)

12 VDD Supply Positive supply voltage (+5V DC)

1.8 Typical Performance Characteristics

following diagrams. The 3 sigma limits represents 99.73% of the SCA103T population.

Figure 4. Typical temperature dependency of SCA103T offset Figure 5. Typical temperature de pendency of SCA103T sensitivity

1.8.1 Additional External Compensation

there is no need for any additional external compensation for offset. sensitivity temperature dependency from 0.013%/°C down to 0.005%/°C.

Figure 6. The temperature dependency of 3

2 Functional Description

2.1 Differential Measurement

amplifier or a microcontroller. efficient noise reduction, improved long term stability and extremely low temperature dependency. the figure below. For differential amplifier connection refer to the recommended circuit diagram. Figure 7. Differential output characteristics

2.2 Voltage to Angle Conversion

the measuring axis direction marking on the top of SCA103T package. Figure 8. Behavior of the analog output

VTI Technologies Oy S ubject to changes 10/19 ySensitivit OffsetVDout −=α ⎛ −= ySensitivit OffsetVDoutarcsinα where Offset is the output of the device at 0° incli nation position, Sensitivity is the sensitivity of the device and VDout is the output of differential amplifier. In the case of differential amplifier connection shown in the chapter Recommended circuit diagram the nominal offset output is 0 V and the sensit ivity is 16 V/g with SCA103T-D04 and 8 V/g with SCA103T-D05. Angles close to 0° inclination can be estimated quite accurately with straight line conversion but for best possible accuracy arcsine conversion is recommended to be used. Following table shows the angle measurement error if straight line conversion is used. Straight line conversion equation: Where: Sensitivity = 280mV/° with SCA103T-D04 or Sensitivity= 140mV/° with SCA103T-D05 Tilt angle [°] Straight line conversion error [°] 0 0 1 0.0027 2 0.0058 3 0.0094 4 0.0140 5 0.0198 10 0.0787 15 0.2185 30 1.668

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 SCA103T supply voltage is fluctuating, the SCA103T output will also vary. When the same reference voltage for both the SCA103T sensor and the measuring part (A/D- converter) is used, the error caused by reference voltage variation is automatically compensated.

2.4 SPI Serial Interface

A Serial Peripheral Interface (SPI) system cons ists of one master device and one or more slave devices. The master is defined as a microcontrolle r providing the SPI clock and the slave as any integrated circuit receiving the SPI clock from the master. The ASIC in VTI Technologies’ products always operates as a slave device in master-slave operation mode. The SPI has a 4-wire synchronous serial inte rface. Data communication is enabled with 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).

Figure 9. Typical SPI connection The SPI interface in VTI products is designed to support any micro controller that uses SPI bus.

• 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 falli ng 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 SCA103T’s internal registers
• data transfer out from MISO starts with the falli ng 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 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 in parallel with the input data. The SPI interface uses an 8-bit instruction (or co mmand) register. The list of commands is given in Table below.

MEAS command is the exit command from Self test. Figure 10. Command and 8 bit temperat ure data transmission over the SPI acceleration signal stored in acceleration data register X. acceleration signal stored in acceleration data register Y.

Figure 11. Command and 11 bit acceleration data transmission over the SPI

2.5 Digital Output to Angle Conversion

To obtain the differential digital output value, Dout, RDAY must be subtracted from RDAX. differential digital output values with -5, -1 0, 1 and 5 degree tilt angles.

2.6 Self Test and Fa ilure Detection Modes

command on the self test input, or through the SPI.

• 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 both in the SPI and analogue output. The self test function is activated digitally by a STX or STY command, and de-activated by a MEAS command. Self test can be also activated applying logic”1” (positive supply voltage level) to ST pins (pins 9 & 10) of SCA103T. The self test Input high voltage level is 4 – Vdd+0.3 V and input low voltage level is 0.3 – 1 V. The self test function must not be activated for both channels at the same time.

Figure 12. Self test wave forms V1 = initial output voltage before the self test function is activated. V2 = output voltage during the self test function. initial value after the specified stabilization time. After a longer time (max. 1 second) V1=V3.

VTI Technologies Oy S ubject to changes 15/19 083.1 197 −= CountsT T2 = Saturation delay T3 = Recovery time T4 = Stabilization time =T2+T3 T5 = Rise time during self test

2.7 Temperature Measurement

The SCA103T has an internal temperature sensor, which is used for internal offset compensation. The temperature information is also available for additional external compensation. The temperature sensor can be accessed via the SPI interface and the temperature reading is an 8-bit word (0…255). The transfer function is expressed by the following formula: Where: Counts Temperature reading T Temperature in °C The temperature measurement output is not calibrated. The internal temperature compensation routine uses relative results where absolute accuracy is not needed. If the temperature measurement results are used for additional external compensation then one point calibration in the system level is needed to remove the offset. With external one point calibration the accuracy of the temperature measurement is about ±1 °C.

3 Application Information

3.1 Recommended Circuit Diagrams a nd Printed Circuit Board Layouts

voltage for both the SCA103T and Analog/Digital converter. Use low pass RC filters with 5.11 kΩ and 10nF on the SCA103T outputs to minimize clock noise. narrow power supply or GND connection strips on PCB. External instrumentation amplifier connection example is shown below. Figure 13. Differential amplifier connection and layout example The recommended connection example for SPI connection is shown below. Figure 14. SPI connection example

3.2 Recommended Printed Ci rcuit Board Footprint

Figure 15. Recommended PCB footprint

4 Mechanical Specifications and Reflow Soldering

4.1 Mechanical Specifica tions (Reference only)

RoHS compliance: RoHS compliant lead-free component. Co-planarity error 0.1mm max. Figure 16. Mechanical dimensions of the SCA103T. (Dimensions in mm)

4.2 Reflow Soldering

normal SMD pick-and-place equipment. Figure 17. Recommended SCA103T body temperature profile during reflow soldering. Ref. Average ramp-up rate (TL to TP) 3°C/second max. 3°C/second max.

• Preheating time and temperatures according to solder paste manufacturer.
• It is important that the part is parallel to t he PCB plane and that there is no angular alignment error from intended measuring direction during the assembly process.
• Wave soldering is not recommended.
• Ultrasonic cleaning is not allowed. The sensing element may be damaged by an ultrasonic cleaning process.

VTI Technologies Oy S ubject to changes 19/19

5 Document Change Control

Version Date Change Description A 1.9.-06 Initial release

6 Contact Information

(head office) VTI Technologies Oy P.O. Box 27 Myllynkivenkuja 6 FI-01621 Vantaa Finland Tel. +358 9 879 181 Fax +358 9 8791 8791 E-mail: sales@vti.fi Germany VTI Technologies Oy Branch Office Frankfurt Rennbahnstrasse 72-74 D-60528 Frankfurt am Main, Germany Tel. +49 69 6786 880 Fax +49 69 6786 8829 E-mail: sales.de@vti.fi USA VTI Technologies, Inc. One Park Lane Blvd. Suite 804 - East Tower Dearborn, MI 48126 USA Tel. +1 313 425 0850 Fax +1 313 425 0860 E-mail sales@vtitechnologies.com Japan VTI Technologies Oy Tokyo Office Tokyo-to, Minato-ku 2-7-16 Bureau Toranomon 401105-0001 Japan Tel. +81 3 6277 6618 Fax +81 3 6277 6619 China VTI Technologies Shanghai Office 6th floor, Room 618

780 Cailun Lu

201203 Shanghai

P.R. China Tel. +86 21 5132 0418 or +86 21 5132 0400 *112 Fax +86 21 513 20 416 E-mail: forename.surname@vti.fi To find out your local sales representative visit www.vti.fi VTI Technologies reserves all rights to modify this document without prior notice.