STMicroelectronics L4964

Overview

L4964 from STMicroelectronics is a monolithic stepdown switching regulator delivering 4 A continuous output current at adjustable output voltages from 5.1 V to 28 V, featuring ±3 % on-chip reference, up to 120 kHz switching frequency, and integrated reset output for microprocessor supervision in industrial power supplies.

For engineers reviewing the L4964 datasheet, L4964 pinout, L4964 application, or L4964 equivalent, key selection criteria include its 4 A current capability, 5.1–28 V output adjustability, soft-start timing control via external capacitor, thermal shutdown at ~140 °C, and open-collector reset output with programmable delay.

Technical Context

The L4964 implements a fixed-frequency PWM control architecture with an internal 5.1 V zener-zap-trimmed reference and sawtooth oscillator. Regulation is achieved by comparing feedback voltage against the reference using an error amplifier whose loop gain is externally set via pin 9 (frequency compensation).

It integrates multiple protection functions: current limiting via internal metal resistor sensing, thermal shutdown at 135–145 °C with hysteresis, remote TTL-level inhibit (pin 6), and synchronous PWM input (pin 7) for multi-device coordination. The reset circuit (pins 12–14) provides a delayed, open-collector output triggered by input or feedback voltage thresholds.

Key Specifications

Pinout & Package

The L4964 is housed in a Multiwatt15 vertical plastic power package (15-lead, TO-220-compatible footprint), optimized for thermal dissipation (R_{th j-case} = 3 °C/W) and high-current PCB layout. Pins 1, 4, and 15 are no-connect and must remain unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2596-ADJ and TPS5430, the L4964 uniquely combines 4 A capability, ±3 % trimmed reference, open-collector reset with capacitor-programmed delay, and multi-device synchronization - making it optimal for industrial systems demanding reliability, precision, and coordinated power management.

Availability

L4964 is available at Aetrix Electronics and suitable for industrial PLC power supplies, telecom line card DC-DC conversion, and test equipment power modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for L4964 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 L4964 belongs to ST's legacy high-current switching regulator product line, designed specifically for rugged industrial power conversion where reliability, thermal robustness, and integrated system supervision (reset, inhibit, sync) are critical.

FAQ

What is the maximum input voltage the L4964 can withstand?

The absolute maximum input voltage at pin 3 is 36 V DC. Exceeding this risks permanent damage. The recommended operating range is 9 V to 36 V, with optimal efficiency observed between 12 V and 28 V input for typical 5.1–28 V output configurations. Transient spikes above 36 V require external clamping.

How is the output voltage adjusted above 5.1 V?

Output voltage is scaled above 5.1 V using a resistor divider from output to pin 10 (feedback) and ground. For example, a 12 V output uses R7 = 6.2 kΩ and R8 = 4.7 kΩ per ST's application note. The divider ratio must maintain ≥10 µA bias current into pin 10 while ensuring loop stability with compensation network on pin 9.

Does the L4964 require an external MOSFET?

No. The L4964 integrates a bipolar transistor output stage capable of delivering 4 A continuously. It does not require an external MOSFET or driver. However, proper heatsinking is essential - its R_{th j-case} of 3 °C/W mandates mechanical attachment to a thermal pad or heatsink for full-load operation above 70 °C ambient.

Can the reset output drive a standard microcontroller reset pin directly?

Yes, but only with an external pull-up resistor (typically 4.7–10 kΩ to +5 V or +3.3 V). Pin 14 is open-collector and sinks ≥50 mA when active low. It asserts reset when input voltage falls below V_ref − 100 mV and de-asserts after a capacitor-programmed delay once voltage rises above threshold - matching standard MCU reset timing requirements.