Signal conditioner preps data from consumer pressure & thermopile sensors

January 27, 2016 // By Graham Prophet
IDT’s ZSSC3224 is a 24-bit sensor signal conditioner (SSC) IC designed for energy-efficient designs with consumer barometric pressure and thermopile sensors. The part is one of the first released by the former ZMDI (Dresden, Germany) since its acquisition by IDT in 2015.

The device has an integrated 26-bit digital signal processor (DSP) for linearisation and calibration functions, for high-resolution consumer, industrial, white goods and medical applications, as well as phones and tablets, and joins a family of SSCs designed for high-end sensor modules: it delivers high-accuracy amplification and a 24-bit precision full-featured analogue-to-digital converter.

The ZSSC3224 is suitable for high-precision measurement systems, including barometric altitude measurement for portable navigation or emergency call systems; altitude measurement for car navigation; pressure measurements inside hard discs; and weather forecasting equipment. The device—available in die and wafer form—can also adapt thermopile sensors to enable contactless temperature measurements of objects or human body temperature.

Michael Georgi, product marketing manager, adds, “The device is designed for use with resistive pressure sensors as well as absolute voltage sensors such as thermopiles. A stacked die assembly, combined with a dedicated MEMS sensor element, can provide the lowest form factor on the market for MEMS-based sensors.”

Targeting battery-driven, low-power devices, features such as 1 mA typical overall current consumption, 20 nA typical sleep mode current, and a 1.68V to 3.6V power supply range combine with an intelligent power-save scheme to help ensure the lowest overall current consumption. The device also offers internal filter options for low noise output signals and intelligent alarm and interrupt capabilities. The ZSSC3224 eliminates the need for an external buffer capacitor and it provides power supply rejection ratio (PSRR) of up to 90 dB at 2V, making it attractive for applications in harsh environments.

Digital compensation of signal offset, sensitivity, temperature and non-linearity is accomplished via an internal correction algorithm with coefficients stored on-chip in a reliable, nonvolatile, programmable memory. Other features include: Quadratic form factor, optimised for stacked die assembly; operating temperature range:-40°C to 85°C; programming via software provided in evaluation kit; accuracy better than ±0.10% full-scale output; internal temperature measurement and signal processing; and fully corrected digital output signal simplifying the system design.