STMicroelectronics TSU111ICT

Overview

TSU111ICT from STMicroelectronics is a nanopower, rail-to-rail input/output operational amplifier optimized for ultra-low-power sensor signal conditioning. It delivers 900 nA typical supply current at 25 °C, 150 µV max. input offset voltage at 25 °C, 3.6 µVpp low-frequency noise (0.1–10 Hz), 1.5–5.5 V supply range, and 11.5 kHz gain bandwidth product - enabling multi-decade battery life in gas sensing and wearable applications.

For engineers reviewing the TSU111ICT datasheet, TSU111ICT pinout, TSU111ICT application, or TSU111ICT equivalent, key selection criteria include sub-µA quiescent current stability across temperature, guaranteed 235 µV max. offset over –40 to 85 °C, EMI robustness (79 dB @ 900 MHz), and validated trans-impedance performance with electrochemical sensors.

Technical Context

The TSU111ICT employs complementary PMOS/NMOS input pairs to achieve true rail-to-rail input operation (V_ICM = V_CC– – 0.1 V to V_CC+ + 0.1 V) without phase reversal. Its CMOS architecture enables 10 pA max. input bias current at 25 °C and supports stable closed-loop operation with capacitive loads up to 100 pF when using recommended R_iso compensation.

It features a single-pole dominant-pole compensation scheme yielding 60° phase margin and 10–11.5 kHz gain bandwidth across 1.8–5 V supplies. The device maintains 76–121 dB common-mode rejection ratio and 92–116 dB supply voltage rejection ratio, with EMIRR of 79 dB at 900 MHz - critical for noisy portable environments.

Key Specifications

Pinout & Package

TSU111ICT is supplied in SC70-5 (SOT-353) package: 1.25 mm × 1.65 mm, 0.65 mm pitch, 5-pin surface-mount. Exposed pad not present. Compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSU101ICT, TSU111ICT trades 250 nA extra current for 150 µV lower offset and 7.5 kHz higher bandwidth - making it optimal for battery-powered gas sensors needing both longevity and ppm-level accuracy. Against TSZ121ICT, it sacrifices 20 µV offset precision to cut supply current by 2×, extending CR2032 lifetime from ~12 to >25 years.

Availability

TSU111ICT is available at Aetrix Electronics and suitable for gas sensing systems, PIR motion alarms, energy-harvesting wearables, and battery current monitoring requiring stable component supply across automotive, industrial, and medical design cycles.

Supply support for TSU111ICT 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The TSU11x series belongs to ST's nanopower precision op-amp product line, engineered specifically for battery-constrained, high-accuracy sensor front-ends where decades-long operation and µV-level DC integrity are non-negotiable.

FAQ

What is the maximum capacitive load the TSU111ICT can drive stably?

The TSU111ICT remains unity-gain stable with up to 100 pF capacitive load when using the recommended series isolation resistor (R_iso) per Figure 30 in DS11846. Without R_iso, oscillation may occur above 30 pF. For loads >100 pF, external buffer stages or active compensation are required - the device is not designed for direct driving of long cables or large LCD bias networks.

Can the TSU111ICT operate from a single 1.5 V alkaline cell?

Yes - the TSU111ICT is fully specified down to 1.5 V supply and maintains 900 nA typical ICC, 150 µV max. V_IO, and rail-to-rail input/output functionality at this voltage. Its 1.5 V minimum rating enables direct use with aging alkaline cells whose voltage drops below 1.8 V, unlike many competing nanopower op-amps that require ≥1.8 V.

Does the NC pin (Pin 2) require any PCB layout treatment?

Pin 2 is a true no-connect with no internal bond wire or silicon connection. It must remain electrically floating - no trace routing, solder mask opening, or thermal pad attachment. ST confirms this pin has zero electrical interaction with internal circuitry; grounding or connecting it risks parasitic coupling or assembly defects but causes no functional failure.

How does the TSU111ICT handle input overvoltage beyond the supply rails?

The TSU111ICT integrates ESD diodes from each input to V_CC+ and V_CC–, rated for 4 kV HBM. Input voltages exceeding rails by >0.3 V forward-bias these diodes, requiring external series resistors to limit current to ≤10 mA (per Table 1). Without current limiting, sustained overvoltage can cause latch-up or parametric shift - especially critical in electrochemical sensor bias circuits where reference electrodes float near V_CC+.