Interface IC gives 14-bit direct digital output from bridge sensors

October 26, 2015 // By Graham Prophet
Mixed-signal semiconductor supplier ZMDI (Dresden, Germany) has posted details of the ZSC31014, a CMOS IC for highly accurate amplification and analogue-to-digital conversion of differential and half-bridge input signals.

The ZSC31014 can compensate the measured signal for offset, 1 st and 2 nd order span, and 1 st and 2 nd

order temperature (Tco and Tcg). It is suited for sensor specific correction of bridge sensors. Digital compensation of signal offset, sensitivity, temperature drift, and non-linearity is accomplished via an internal digital signal processor running a correction algorithm with calibration coefficients stored in a non-volatile EEPROM.

The ZSC31014 is adjustable to nearly all piezo-resistive bridge sensors. Measured and corrected bridge values are provided at digital output pins, which can be configured as I ²C or SPI. The digital I ²C interface can be used for a simple PC-controlled calibration procedure to program calibration coefficients into an on-chip EEPROM. The calibrated ZSC31014 and a specific sensor are mated digitally: fast, precise, and without the cost overhead associated with trimming by external devices or laser trimming. The ZSC31014’s integrated diagnostics functions are suited for safety-critical applications.

Features include;

High accuracy (±0.1% FSO @ -25 to +85°C; ±0.25% FSO @ -40 to +125°C)

2nd order charge-balancing analogue-to-digital converter provides low noise, 14-bit data at sample rates exceeding 2 kHz

Fast power-up to data output response: 3msec at 4 MHz

Digital compensation of sensor offset, sensitivity, temperature drift, and non-linearity

Eight programmable analogue gain settings combine with a digital gain term; accommodates

bridges with spans <1 mV/V and high offset

Internal temperature compensation for sensor correction and for corrected temperature output

48-bit customer ID field for module traceability

Supply voltage is 2.7V to 5.5V; current consumption as low as 70 μA depending on programmed sample rate; in low power sleep mode it uses <2μA @ 25°C.