English German French Chinese Japanese Russian

PicoStrain - Stands for an innovative digital concept to measure resistance

PS09 Evaluation-Kit

Measuring strain gages is one of the big challenges for sensor technology, especially the weighing industry. Due to the small excitation of the strain gages on a load cell of only 0.2 % (2000 ppm) full scale, and due to the high resolution of 16 Bit and more, the resistors must be measured with a precision deeply in the ppb range. Reasonably, this can only be done measuring the ratio of the resistors.

Here the ® measuring principle is breaking new grounds compared to A/D converters. The ratio of the resistors is ascribed to a time interval measurement, not to a voltage difference like in Wheatstone bridges. The sensor's resistors together with a capacitor act as low-pass filters. The capacitor, charged to Vcc, is discharged through the sensor's resistors. The discharge time to trigger level (selectable) is precisely measured by a TDC (Time-to-Digital Converter).


The ® integrated circuits are realized without any analog component. Again, acam uses its TDC technology to set new standards in circuit design.


  • No elaborate supply of the strain gage
  • No need for a full-bridge, 2 resistors (half-bridge) are sufficient
  • Reduction of the current into the strain gage (total system current down to a few µA)
  • Easy temperature compensation
  • No reference voltage
  • Flexibility in update rate, precision and current consumption
  • Wide temperature range up to process limits


  • Strain gage sensors
  • Force sensors
  • Pressure sensors
  • Torque wrenches
  • Digital load cells
  • Bathroom scales (solar and battery)
  • Kitchen scales (solar and battery)
  • Legal for trade scales (OIML, NTEP)



General Description

PicoStrain measuring principle