Zero-drift op amps support precision sensing in wearable products

June 5, 2014. STMicroelectronics’ TSZ121 family of zero-drift op amps target Internet-of-Things (IoT) or wearable-device applications and can find use in temperature sensors, wellness and fitness monitors, and automotive controls.

With input-offset voltage of 5 µV at 25°C and temperature stability of 30 nV/°C, these chopper-stabilized op amps are suitable for front-end signal conditioning or low-side current measurement. Their precision guarantees accuracy without trimming, thereby saving component count and manufacturing overhead. Ultra-low temperature drift prevents system-performance degradation at higher temperature without requiring self-calibration.

The TSZ121, TSZ122, and TSZ124 expand ST’s high-precision line-up, which also includes non-switching op amps such as the TSV711 and TSV731. The devices operate from 1.8 V to 5.5 V, with quiescent current below 40 μA at 5 V and with a gain-bandwidth product of 400 kHz.

The single-channel TSZ121 is pin- and package-compatible with comparable devices from other manufacturers. The dual-channel TSZ122 offers MiniSO-8 and SO-8 packages plus the option of a miniature 2-mm x 2-mm DFN8.

The TSZ121 family is in mass production now, with devices priced from $0.95 for the TSZ121 in SC70-5 or SOT-25L package for orders of 1,000 pieces. Corresponding prices for dual TSZ122 and quad TSZ124 versions start from $1.24 and $1.62, respectively.

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