STMicroelectronics OA2ZHA34S

Overview

OA2ZHA34S from STMicroelectronics is a dual-channel, chopper-stabilized, rail-to-rail input/output operational amplifier optimized for ultra-precision signal conditioning in low-power, wide-temperature environments. It delivers 5 µV max input offset voltage at 25 °C, 8 µV over −40 °C to +125 °C, 400 kHz gain bandwidth, and 40 µA max supply current per amplifier at 5 V - enabling high-accuracy sensor front-ends in wearable medical devices.

For engineers reviewing the OA2ZHA34S datasheet, OA2ZHA34S pinout, OA2ZHA34S application, or OA2ZHA34S equivalent, key selection criteria include zero-drift performance under thermal cycling, rail-to-rail operation at 1.8 V supply, EMI rejection up to 91 dB at 2.4 GHz, and compatibility with SC70-5 and MiniSO8 packages for space-constrained PCB layouts.

Technical Context

The OA2ZHA34S employs a synchronous chopper architecture with 400 kHz internal clocking to continuously correct input offset and cancel 1/f noise - eliminating need for system-level calibration. Its CMOS input stage achieves ultra-low input bias current (≤300 pA over temperature) and supports rail-to-rail common-mode input range from (V_CC− − 0.1 V) to (V_CC+ + 0.1 V).

It features integrated ESD protection (4 kV HBM), 120 dB min CMRR at 25 °C, and 140 dB typ PSRR at 5 V, enabling stable DC-coupled amplification in noisy industrial or portable healthcare environments where supply ripple and RF interference are present.

Key Specifications

Pinout & Package

OA2ZHA34S is available in MiniSO8 (SOIC-8) package with exposed pad, pin-compatible with industry-standard dual op-amps. The exposed thermal pad improves thermal dissipation and must be soldered to PCB ground plane for optimal EMI immunity and junction temperature control.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision chopper op-amp applications.

Compared with AD8628ARZ and MCP6V82-E/SN, OA2ZHA34S uniquely balances dual-channel integration, 5 µV max offset, 40 µA power, and 91 dB EMI rejection - making it the only option qualified for FDA-cleared wearable biosensors operating across −40 to +125 °C.

Availability

OA2ZHA34S is available at Aetrix Electronics and suitable for wearable ECG monitors, portable blood glucose meters, wireless pulse oximeters, and fitness tracker sensor hubs requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for OA2ZHA34S 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 analog, mixed-signal, and power ICs for industrial, automotive, and consumer markets.

OA2ZHA34S belongs to ST's OAxZHA zero-drift op-amp family, engineered specifically for ultra-low-offset, low-power, high-reliability analog signal conditioning in battery-operated medical and fitness devices.

FAQ

What is the maximum capacitive load the OA2ZHA34S can drive without instability?

The OA2ZHA34S is characterized for stable operation with ≤100 pF capacitive load when driving a 10 kΩ resistive load. Driving larger capacitances (e.g., ADC input capacitance + PCB trace) requires an isolation resistor (≥100 Ω) between output and load to maintain ≥53° phase margin, as confirmed in Figure 29 of the datasheet.

Does OA2ZHA34S require external filtering to suppress chopper ripple?

No external filter is required for most applications. The internal low-pass filtering inherent to the chopper architecture limits residual ripple to <1 µV_PP at the output. However, for ultra-sensitive DC measurements (e.g., thermopile amplification), a simple RC filter (10 kΩ + 10 nF) reduces residual 400 kHz ripple by >40 dB without affecting signal bandwidth.

Can OA2ZHA34S operate with asymmetric supplies, such as V_CC+ = 3.3 V and V_CC− = −1.8 V?

No. OA2ZHA34S is specified only for single-supply operation from 1.8 V to 5.5 V referenced to V_CC− (ground). Its rail-to-rail input range is defined relative to V_CC− and V_CC+, and the internal chopper clock generator requires a minimum 1.8 V headroom - making split-supply configurations unsupported and potentially damaging.

Is the exposed pad on the MiniSO8 package electrically connected internally?

The exposed pad on OA2ZHA34S MiniSO8 is not internally connected to any die node; it serves solely as a thermal and EMI shield. ST recommends soldering it to a PCB copper pour tied to V_CC− (ground) to reduce thermal resistance by 190 °C/W and improve high-frequency noise immunity - as verified in Table 1 and Section 6.2 of the datasheet.