STMicroelectronics E-L4981A

Overview

E-L4981A from STMicroelectronics is a fixed-frequency average-current-mode PWM power factor correction (PFC) controller IC designed for boost pre-regulator topologies. It achieves up to 0.99 power factor, limits line current distortion to <5%, supports universal AC input (85–265 V_AC), and integrates a 5.1 V ±2% reference, programmable UVLO, and totem-pole gate driver capable of >1 A peak output. It is used in industrial and consumer AC-DC power supplies requiring high-efficiency PFC compliance.

For engineers reviewing the E-L4981A datasheet, E-L4981A pinout, E-L4981A application, or E-L4981A equivalent, key selection considerations include its fixed 100 kHz nominal switching frequency (L4981A variant), average-current-mode control architecture, IPK-based peak current limiting, and integrated protections including OVP, OCP, and soft-start - all critical for stable, low-THD boost PFC design.

Technical Context

The E-L4981A implements an analog multiplier-based average-current-mode control loop with RMS line voltage feedforward (Pin 7), load feedforward (Pin 6), and precise error amplifier compensation (Pin 13). Its internal oscillator uses external ROSC/COSC components to fix frequency at ~100 kHz (typ), and it drives external MOSFETs via a bipolar/DMOS totem-pole output (Pin 20) with 0.5–0.8 V low-state and 11.5–12.5 V high-state drive capability under load.

It features dual-stage protection: overvoltage protection compares boost output against a 5.1 V internal reference (Pin 3), while peak current limiting uses Pin 2 with resistor-programmable threshold (±30 mV comparator offset). The device operates from 12–19.5 V supply, draws only 0.3 mA startup current, and includes programmable UVLO with hysteresis (14.5–16.5 V turn-on, 9–11 V turn-off).

Key Specifications

Pinout & Package

Available in DIP20 and SO20 packages (BCD 60II technology); thermal resistance is 80 °C/W (DIP20) and 120 °C/W (SO20). Pinout validated per STMicroelectronics datasheet Rev. 16 (Nov. 2001).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power factor correction controller applications.

Compared with UCC3817DW and FAN4803SJX, the E-L4981A offers superior line/load regulation via dedicated feedforward pins, higher gate drive strength for direct MOSFET control, and tighter THD performance - making it optimal for 200–360 W universal-input PFC stages demanding Class D compliance.

Availability

E-L4981A is available at Aetrix Electronics and suitable for industrial AC-DC power supplies, LED driver front-end stages, and medical equipment power modules requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for E-L4981A 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 ICs.

The L4981 series belongs to ST's legacy power factor correction controller product line, engineered specifically for continuous-conduction-mode (CCM) boost PFC pre-regulators in universal-input AC-DC systems up to 400 W.

FAQ

What is the maximum recommended operating temperature for E-L4981A?

The E-L4981A specifies an operating ambient temperature range of –40°C to +125°C. Thermal derating begins above +70°C ambient, where power dissipation must be limited to 1 W (DIP20) or 0.6 W (SO20) to maintain junction temperature within safe limits per R_{th j-amb} values (80°C/W and 120°C/W respectively).

Can E-L4981A be used with discontinuous conduction mode (DCM) boost topologies?

No - the E-L4981A is explicitly designed for continuous conduction mode (CCM) boost PFC operation. Its average-current-mode control architecture, multiplier-based reference generation, and compensation structure assume CCM waveforms; DCM use would cause instability and inaccurate current regulation per STMicroelectronics AN628 application note.

How is the overvoltage protection threshold set on E-L4981A?

OVP threshold is set externally via a resistive divider from the boost output to Pin 3 (OVP), referenced to the internal 5.1 V comparator threshold. For example, a 442 V trip point requires a 87:1 divider ratio (e.g., 806 kΩ top, 9.3 kΩ bottom), as demonstrated in Figure 9A of the datasheet.

Does E-L4981A support synchronization with other controllers?

Yes - Pin 16 (SYNC) functions as both CMOS-compatible synchronization input and output. When configured as input, it accepts external clock signals to align switching edges; as output, it delivers synchronized rectangular pulses usable for interleaving or coordinating secondary controllers in multi-rail systems.