STMicroelectronics ST732M28R

Overview

ST732M28R from STMicroelectronics is a 300 mA, fixed 2.8 V output low-dropout (LDO) linear regulator in SOT23-5L package, designed for post-regulation and battery-powered systems requiring ultra-low quiescent current (5 µA typ.), wide input range (2.5–28 V), ±2% output accuracy, and thermal/current protection. It operates from –40 °C to +125 °C and stabilizes with 0.47 µF ceramic output capacitors.

For engineers reviewing the ST732M28R datasheet, ST732M28R pinout, ST732M28R application, or ST732M28R equivalent, key selection criteria include dropout voltage at 300 mA (≤1.2 V), load regulation (0.0001 %/mA), PSRR at 1 kHz (75 dB), and compatibility with low-ESR ceramic capacitors in space-constrained industrial and safety-critical modules.

Technical Context

The ST732M28R implements a bandgap-referenced error amplifier with internal bias generator and overtemperature/overcurrent protection circuitry. Its SOA-based current limit varies with (VIN–VOUT) to constrain power dissipation under overload, while thermal shutdown triggers at 160 °C with 20 °C hysteresis.

Stability is achieved using a single-pole compensation scheme compatible with low-ESR ceramic capacitors ≥0.47 µF. The device requires no external components for basic operation but mandates close placement of 0.1 µF input and ≥0.47 µF output capacitors to ensure loop stability across –40 °C to +125 °C.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 1.45 mm height, 2.95 mm × 1.60 mm footprint, with exposed pad not connected internally. Designed for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with XC6219B282MR-G and AP2204K-2.8TRG1, the ST732M28R uniquely combines 28 V input capability, 5 µA IQ, and 300 mA output in SOT23-5L - making it the sole option for high-VIN, ultra-low-power industrial sensing nodes requiring long-term reliability.

Availability

ST732M28R is available at Aetrix Electronics and suitable for electronic meters, smoke detectors, and industrial PLC I/O modules requiring stable component supply, long-lifecycle support, and guaranteed parametric compliance across temperature extremes.

Supply support for ST732M28R 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, specializing in power management, analog, microcontrollers, and automotive-grade ICs with ISO/TS 16949 certified manufacturing.

The ST732 series belongs to ST's high-voltage, ultra-low-IQ LDO portfolio, engineered specifically for battery-backed safety and metering applications where decades-long operational life and robustness against voltage transients are mandatory.

FAQ

What is the minimum output capacitance required for ST732M28R stability?

The ST732M28R requires a minimum 0.47 µF ceramic capacitor (X5R/X7R) on VOUT with ESR between 5 mΩ and 500 mΩ. This value is validated across –40 °C to +125 °C and ensures phase margin >45°; smaller values risk oscillation under load transients.

Can ST732M28R operate with a 3.3 V input supplying 2.8 V output at 300 mA?

No - at 300 mA, the dropout voltage is 600–1200 mV. With 3.3 V input, the maximum sustainable output is 2.1–2.7 V, below the 2.8 V nominal. Minimum recommended VIN is 3.4 V (2.8 V + 600 mV) for full 300 mA regulation.

Does ST732M28R support reverse-voltage protection?

No - the device lacks integrated reverse-polarity protection. If reverse input voltage exceeding –0.3 V may occur, an external Schottky diode in series with VIN is required to prevent latch-up or damage per absolute maximum ratings.

How does the current limit behave under varying input-output differential?

The ST732M28R implements a voltage-dependent current limit: short-circuit current decreases as (VIN–VOUT) increases, capping power dissipation. At VIN = 2.5 V, ISC ≈ 450 mA; at VIN = 28 V, ISC drops to ~100 mA - preventing thermal runaway during sustained overload.