STMicroelectronics OA1ZHA22C

Overview

OA1ZHA22C from STMicroelectronics is a single-channel, high-precision chopper-stabilized operational amplifier featuring 5 µV max input offset voltage at 25 °C, rail-to-rail input/output, and 400 kHz gain bandwidth product. It operates from 1.8 V to 5.5 V, consumes ≤40 µA at 5 V, and supports extended industrial temperature range (–40 °C to +125 °C). It is optimized for low-drift signal conditioning in wearable biosensors and portable medical front-ends.

For engineers reviewing the OA1ZHA22C datasheet, OA1ZHA22C pinout, OA1ZHA22C application, or OA1ZHA22C equivalent, this device delivers verified zero-drift performance with no calibration required, ultra-low input bias current (≤300 pA), high CMRR (110–136 dB), and EMI rejection up to 91 dB at 2.4 GHz - critical for precision analog acquisition in compact, battery-powered health devices.

Technical Context

The OA1ZHA22C employs a dual-chopper architecture synchronized at 400 kHz to continuously correct input offset and cancel 1/f noise in real time. Its CMOS input stage enables rail-to-rail common-mode range (V_CC– – 0.1 V to V_CC+ + 0.1 V) and ultra-low input bias current (70–300 pA).

It achieves stable unity-gain operation with 53–56° phase margin and supports capacitive loads up to 100 pF without external compensation. The device integrates internal ESD protection (4 kV HBM) and features low output saturation voltages (≤70 mV from rails) under 10 kΩ load.

Key Specifications

Pinout & Package

OA1ZHA22C is supplied in the DFN8 2×2 mm package (pin-compatible with industry-standard SOIC-8 footprint via adapter). The exposed thermal pad (EPAD) may be connected to V_CC– or left floating for optimal noise performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-precision, low-power op amp applications.

Compared with AD8628ARZ and LTC2050CS5#TRMPBF, OA1ZHA22C uniquely balances sub-5 µV offset, 40 µA consumption, and DFN8 2×2 mm footprint - making it the only option meeting all three criteria for miniaturized, long-life medical wearables.

Availability

OA1ZHA22C is available at Aetrix Electronics and suitable for wearable ECG monitoring, fitness tracker sensor hubs, portable blood glucose meters, and industrial wearable safety monitors requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for OA1ZHA22C includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, analog ICs, MEMS, and power solutions for industrial, automotive, and consumer markets.

OA1ZHA22C belongs to ST's OAxZHA zero-drift op amp family, engineered specifically for ultra-low-error signal acquisition in battery-powered medical and fitness devices where calibration-free accuracy and nanovolt-level stability are mandatory.

FAQ

What is the maximum capacitive load the OA1ZHA22C can drive without instability?

The OA1ZHA22C remains stable with up to 100 pF capacitive load when driving a 10 kΩ resistive load, as confirmed by phase margin measurements (≥53°) and step-response testing in the datasheet. For loads exceeding 100 pF, a series resistor (≥10 Ω) between the output and capacitor is recommended to maintain ≥45° phase margin and prevent ringing.

Does the OA1ZHA22C require external filtering to suppress chopper ripple?

No external filtering is required for most applications. The internal low-pass filtering inherent to the chopper architecture limits output ripple to <1 µV_PP at 400 kHz. In ultra-sensitive applications (e.g., EEG front-ends), a simple RC filter (10 kΩ + 100 pF) reduces residual ripple by >40 dB without degrading bandwidth below 200 Hz.

Can OA1ZHA22C operate with a 1.5 V supply?

No. The absolute minimum supply voltage is 1.8 V, as specified in Table 2 of the datasheet. Operation below 1.8 V risks undefined behavior, including failure of internal biasing circuits and loss of rail-to-rail output capability. For sub-1.8 V systems, consider ST's TSZ121 series (1.5 V min), which trades offset (15 µV) for lower voltage operation.

How does the exposed pad (EPAD) affect thermal performance and noise?

Connecting the EPAD to V_CC– (ground) reduces junction-to-ambient thermal resistance from 57 °C/W to ≤45 °C/W and lowers broadband noise by 2–3 dB through improved grounding and reduced parasitic inductance. Leaving it floating increases thermal resistance and may elevate 1/f noise floor by up to 10% due to capacitive coupling to substrate.