STMicroelectronics L4971D013TR

Overview

L4971D013TR from STMicroelectronics is a monolithic step-down switching regulator IC with internal 0.25Ω D-MOS power transistor, delivering up to 1.5A output current across an adjustable output voltage range of 3.3V to 50V. It operates from 8V to 55V input, features ±1% 3.3V internal reference, adjustable 90–300kHz switching frequency, and supports zero-load operation in inhibit mode-used in industrial DC-DC conversion for programmable power supplies and embedded system rails.

For engineers reviewing the L4971D013TR datasheet, L4971D013TR pinout, L4971D013TR application, or L4971D013TR equivalent, key selection criteria include its voltage feedforward regulation, pulse-by-pulse current limiting, soft-start timing via external capacitor, thermal shutdown behavior, and SO16W package compatibility with high-efficiency buck topologies requiring wide VIN and precise VOUT stability.

Technical Context

The L4971D013TR integrates a BCD-process D-MOS power switch with typical R_DS(on) = 0.25Ω and uses voltage feedforward control to maintain stable duty cycle under input ripple. Its error amplifier provides 57dB open-loop gain and 2.5mS transconductance, enabling robust loop compensation via the COMP pin.

Switching frequency is set by external R_OSC and C_OSC, with line- and temperature-stability of ±3% and ±4%, respectively. The device supports hiccup-mode short-circuit protection, feedback disconnection detection, and soft-start charge/discharge currents of 40µA/10µA typical-ensuring controlled startup and fault recovery without external supervision.

Key Specifications

Pinout & Package

Package: SO16W (wide-body SOIC-16), surface-mount, 10.10 × 7.40 mm footprint, 1.27 mm pitch, with exposed thermal pad (not electrically connected). Pins 1, 7, 8, 9, 10, 15, and 16 are NC (no internal connection).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Compared with LM2596S-ADJ and MP2451DT-LF-Z, the L4971D013TR uniquely supports 55V input, voltage feedforward for dynamic line regulation, and true zero-current inhibit-making it optimal for ruggedized, wide-VIN industrial buck stages where reliability under transient stress is critical.

Availability

L4971D013TR is available at Aetrix Electronics and suitable for industrial programmable power supplies, telecom line card bias rails, automotive body control modules, and factory automation I/O power systems requiring stable component supply across extended temperature and voltage ranges.

Supply support for L4971D013TR 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 L4971 belongs to ST's legacy high-voltage buck regulator product line, designed specifically for industrial and telecom applications demanding wide input range, high reliability, and minimal external component count in non-isolated DC-DC conversion.

FAQ

What is the maximum recommended input voltage for continuous operation?

The L4971D013TR has an absolute maximum input rating of 58V, but continuous operation is specified up to 55V per Table 3. Operation at 55V requires strict thermal management: SO16W package power dissipation must remain ≤0.8W, achieved via PCB copper area, airflow, or ambient ≤60°C. Exceeding 55V risks premature thermal shutdown or latch-up.

Can the L4971D013TR regulate output voltages below 3.3V?

No. The internal 3.3V reference is fixed and non-adjustable; the minimum output voltage is 3.3V when FB is connected directly to VOUT. External resistor dividers can only scale upward-e.g., 5.1V, 12V, 24V-not downward. For sub-3.3V outputs, a different controller with adjustable reference or external reference injection is required.

How does the voltage feedforward function impact loop compensation?

Voltage feedforward dynamically adjusts the oscillator ramp amplitude in proportion to VCC, making duty cycle inherently less sensitive to input variation. This reduces the burden on the error amplifier, allowing simpler Type II compensation on the COMP pin-typically one series RC network-without sacrificing line regulation or transient response.

Is the BOOT capacitor polarity-sensitive, and what value is recommended?

Yes-the BOOT capacitor must be a 100nF X7R ceramic with 16V+ rating, connected between BOOT and OUT pins with shortest possible traces. Reverse polarity or insufficient voltage rating causes gate-drive failure and immediate D-MOS latch-up. ST recommends 100nF for 100–300kHz operation; values below 47nF risk shoot-through at high frequencies.