STMicroelectronics ST730MR

Overview

ST730MR from STMicroelectronics is an adjustable 300 mA low-dropout linear regulator in SOT23-5L package, designed for post-regulation and battery-powered systems requiring ultra-low quiescent current (5 µA typ. at no-load) and wide input range (2.5 V to 28 V). It delivers ±0.5% output voltage accuracy at 25 °C, supports output voltages from 1.2 V to VIN − VDROP, and integrates thermal shutdown, current limit, and SOA protection for robust operation in industrial and automotive after-market applications.

For engineers reviewing the ST730MR datasheet, ST730MR pinout, ST730MR application, or ST730MR equivalent, this page provides verified technical context, validated pin functions, confirmed LDO performance parameters (dropout, PSRR, noise), and real-world use cases in smoke detectors, electronic meters, and portable equipment - all grounded in DS13036 Rev 5 specifications.

Technical Context

The ST730MR implements a bandgap-referenced op-amp control loop with internal bias generator and thermal feedback. Its adjustable architecture uses the ADJ pin to set output via external resistor divider (VOUT = 1.2 V × (1 + R1/R2)), enabling precise remote sensing and flexible voltage scaling across input conditions.

Protection logic combines temperature-dependent current limiting (non-constant, dropout-voltage dependent) and thermal shutdown with 20 °C hysteresis (trip at 160 °C, recover at ~140 °C). The enable circuitry features TTL-compatible thresholds (EN < 0.35 V = shutdown, EN > 1.2 V = active) and sub-100 nA leakage.

Key Specifications

Pinout & Package

SOT23-5L package: 2.95 mm × 1.60 mm × 1.45 mm body height, thermally enhanced leadframe, RoHS-compliant ECOPACK2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6219B122MR and MIC5205-3.3YM5, the ST730MR uniquely combines adjustability, 300 mA capability, ultra-low IQ, and full protection suite - making it the only viable choice for battery-backed industrial and safety-critical systems requiring design flexibility and long-term reliability.

Availability

ST730MR is available at Aetrix Electronics and suitable for electronic meters, smoke detectors, portable medical devices, and automotive after-market modules requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for ST730MR 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, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The ST730 product line targets ultra-low-power, wide-input-voltage LDO regulation for battery-constrained and harsh-environment applications - emphasizing longevity, robustness, and design flexibility over cost-optimized simplicity.

FAQ

What is the minimum output capacitor required for ST730MR stability?

The ST730MR requires a minimum 0.47 µF ceramic capacitor (X5R/X7R) on the output with ESR between 5 mΩ and 500 mΩ. This value is validated across temperature and load conditions per DS13036 Section 6.1. Using smaller capacitance or outside the ESR range risks oscillation or instability during load transients.

Can ST730MR be used with input voltages below 2.5 V?

No - the absolute minimum operating input voltage is 2.5 V per Table 2 and Table 5 of DS13036 Rev 5. Operation below this threshold violates the device's specified operating conditions and may result in unregulated output or undefined behavior, including failure to start up or maintain regulation.

How does the current limit behave under varying dropout conditions?

The ST730MR implements a SOA-based current limit that decreases as (VIN − VOUT) increases - ensuring maximum power dissipation remains within safe limits. As shown in Figure 18, short-circuit current drops from ~450 mA at 0.5 V dropout to ~200 mA at 25 V dropout, preventing thermal runaway during fault conditions.

Is the ADJ pin internally connected in the ST730MR variant?

Yes - ST730MR is the adjustable version, so Pin 4 (ADJ) is internally connected to the 1.2 V reference and must be externally biased via a resistor divider. This is explicitly defined in Table 1 (Pin Description) and Figure 2 (Block diagram – Adjustable version) of DS13036 Rev 5.