Time-to-Digital-Converters by Acam
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Time to Digital Converters

TDC - GP1
TDC - GP2
TDC - GP21
TDC - GP22
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Time-to-Digital Applications
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PICOSTRAIN

Time to Digital Converters for Digital Strain Gage

PICOSTRAIN PS08
PICOSTRAIN PS081
PICOSTRAIN PS09
PICOSTRAIN PS021
Strain Gage Applications
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PICOCAP

Time to Digital Converters for Capacitance Measurement

PICOCAP PCap01
PICOCAP PS021
PICOCAP PSA21
Capacitance Applications
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PICOTURN

Time to Digital Converters for Speed Sensors

PICOTURN 2G
PICOTURN BM/SM
Speed Sensor Applications
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PS021 - Digital Amplifier for Strain Gage

Digital Front End for Measurement of Strain Gage
The PSØ21 is a digital front-end device for measuring strain gages. Using PICOSTRAIN® measuring principle the PSØ21 provides a high degree of flexibility.

Low Current - High Precision - Beats 24-bit A/D Converters
The current consumption of the total system, including the sensor, can be reduced down to less than 100 μA. The precision to be achieved is better than with most 24-bit A/D-converters and even surpasses them at high measurement rates.

Full, Half, and Wheatstone Bridge Combinations Capable

The PSØ21 is capable of measuring 2 Wheatstone bridges, 2 full or 4 half-bridges. Driving one half bridge is also possible without any loss in precision. An additional port for temperature measurement, patented compensation methods and a serial SPI interface offers the PSØ21 as an innovative front end to strain gage applications.
PICOSTRAIN® Circuits
PS021 - Bridge Connections
PS021 - Rdson/Gain Compensation
PS021 - Span, Gain - Offset, Drift
PS021 - Capacitor, Comparator
PS021 - Oscillator, Cycle Time
PS021 - Averaging, Temperature
PS021 - Performance
PSA21 - Evaluation System
PS021 - Data Sheet

PS021 Chip

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PS021 - Circuit Features

  • Up to 2 full- or 4 halfbridges
  • Up to 2 Wheatstone bridges
  • Capable of driving only a halfbridge without any loss in precision
  • For compensated or non-compensated bridges
  • Adaptation of compensation resistor's Tk by software
  • Offset and span compensation internally separated (mathematically) - bridge offset trim not needed
  • Resistance strain gauge: 350 Ohm to 10 kOhm
  • Programmable resolution: Up to 19 Bit (20nV rms or 500,000 scale div) @ 2 mV/V strain and 5 Hz update rate
  • High Measurement rate: Up to 50 kHz with high resolution (12.4 ENOB @ 4 kHz and 2 mV/V max. strain)
  • Extremely low current consumption possible
  • Possible current down to 15 µA (incl. SG) at 1 Hz and 10 ENOB with 1 kOhm SG and 1000 µ strain
  • High stability with temperature, low gain error (< 1 ppm/K)
  • No need for a pre-amplifier
  • No separate supply of Strain Gage
  • No separate reference voltage
  • Optional Single-conversion mode
  • Separate temperature measurement
  • Optional capacity measurement
  • Serial interface (SPI compatible)
  • Supply voltage I/O and SG: 1.8 ... 5.5 V
  • Separate Supply for interface I/Os
  • Supply voltage PSØ21: 1.8 ... 3.6 V
  • Op. temperature range -40°C ... +120°C
  • QFN48 / QFP48 package (body size 7 x 7 mm²)
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PS021 - Circuit Block Diagram and Package Outline

Block Diagram

Package Outline

Schematic

PS021 Block Diagram PS021 Package Outline PS021 Schematic
Click the images for a closup view
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Applications
Weight Scales Calibrated Weight Scales Telemetric Applications
Force Sensors Load Cells General Strain Gage Amplifiers
Solar Cell Driven Equipment Solar Cells Pressure Sensors (also 4 - 20 mA)
Battery Driven Devices Strain Gage Measurement Digital Strain Gage Measurement