Zero-drift op amps target precision sensing in wearable products

June 06, 2014 // By EDN
STMicroelectronics' TSZ121 family of zero-drift op amps provide accuracy and precision for battery-powered, connected or wearable-device applications including 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-stabilised 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.

Very high accuracy and stability, combined with speed/power-consumption ratio, make these zero-drift op amps a suitable choice for sensor and control interfaces in a wide range of battery-powered IoT applications.

TSZ121, TSZ122 and TSZ124 expand a high-precision line-up which also includes non-switching op amps such as the TSV711 and TSV731, so offering choices for a wide range of system and application requirements. The devices operate from 1.8V to 5.5V, with quiescent current below 40 µA at 5V, gain-bandwidth product of 400 kHz, and ultra-low input bias current.

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 x 2 mm DFN8. By also offering the TSZ124 quad op amp in TSSOP-14 and 3 x 3 mm QFN16, this family provides the broadest choice of zero-drift op amps.

Pricing is from $0.95 for the TSZ121 in SC70-5 or SOT-25L (1,000). Dual TSZ122 and quad TSZ124 versions start from $1.24 and $1.62 respectively.

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