STMicroelectronics L4981BD013TR

Overview

L4981BD013TR from STMicroelectronics is a fixed-frequency average-current-mode PWM power factor correction (PFC) controller IC designed for boost pre-regulator topologies. It delivers up to 0.99 power factor, limits line current THD to <5%, supports universal AC input (85–265 V_AC), integrates a ±2% precision 5.1 V reference, and features a totem-pole gate driver capable of >1 A peak output for MOSFET/IGBT switching in industrial SMPS.

For engineers reviewing the L4981BD013TR datasheet, L4981BD013TR pinout, L4981BD013TR application, or L4981BD013TR equivalent, key selection criteria include its average-current-mode control architecture, programmable UVLO threshold via Pin 15, fixed-frequency operation (L4981B variant), integrated OVP/OCP protection, and SO-20 package compatibility with high-density PFC board layouts.

Technical Context

The L4981BD013TR implements an analog multiplier-based average-current-mode control loop that generates a sinusoidal reference current proportional to rectified line voltage (via VRMS pin) and load condition (via LFF pin), eliminating slope compensation. Its internal error amplifier regulates boost output voltage through a voltage divider on Pin 14, while the current amplifier compares sensed inductor current (Pin 9) against the multiplier output to drive the gate driver (Pin 20).

Unlike voltage-mode controllers, it uses continuous conduction mode (CCM) with real-time feedforward of line RMS (Pin 7) and load (Pin 6) to achieve fast transient response and stable regulation across 85–265 V_AC inputs. The oscillator frequency is set by external ROSC (Pin 17) and COSC (Pin 18), with typical f_SW = 100 kHz (±15%) at T_J = 25°C and V_CC = 18 V.

Key Specifications

Pinout & Package

Package: SO-20 (Small Outline, 20-pin, 0.5 mm pitch, 12.6 × 7.6 mm body). RoHS-compliant, surface-mount, thermal resistance R_{th j-amb} = 120 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UC3854BDW and FAN4803SJX, the L4981BD013TR offers superior integration (on-chip 5.1 V reference, totem-pole driver, feedforward inputs), higher power scalability (up to 400 W demonstrated), and tighter THD control (<5% vs. ≥7% typical for UC3854), making it optimal for industrial-grade PFC stages demanding reliability and regulatory compliance.

Availability

L4981BD013TR is available at Aetrix Electronics and suitable for industrial switch-mode power supplies, medical AC-DC adapters, and LED streetlight drivers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for L4981BD013TR 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The L4981 series belongs to ST's legacy MultiPower BCD technology product line, engineered specifically for high-voltage, high-efficiency power conversion ICs with integrated bipolar/DMOS drivers and precision analog blocks for PFC and SMPS applications.

FAQ

What is the difference between L4981A and L4981B variants?

The L4981A uses fixed-frequency operation with SYNC input/output (Pin 16) for external clock synchronization, while the L4981B employs frequency modulation (FREQ-MOD) on Pin 16 to vary switching frequency with line voltage-reducing acoustic noise at light loads. Both share identical pinout, protection features, and average-current-mode architecture, but only L4981B supports modulated frequency.

Can L4981BD013TR operate without external soft-start capacitor?

No. An external capacitor on Pin 12 (SS) is mandatory: the internal 100 µA current source charges it to control duty-cycle ramp-up. Omitting it causes uncontrolled inrush current, potential OCP triggering, and stress on input rectifier and bulk capacitor. Typical values range from 100 nF to 1 µF depending on desired soft-start time (e.g., 1 µF ≈ 10 ms).

How is overvoltage protection configured on Pin 3 (OVP)?

OVP is configured using a resistive divider from boost output to Pin 3 and GND. When the divided voltage exceeds the internal 5.1 V reference ±20 mV, the controller shuts down. For a 442 V OVP threshold (as in Figure 9B), a 806 kΩ top resistor and 5.1 kΩ bottom resistor yields ~5.1 V at Pin 3, with 250 mV hysteresis ensuring clean recovery after fault clearance.

Does L4981BD013TR support discontinuous conduction mode (DCM)?

No. The L4981BD013TR is designed exclusively for continuous conduction mode (CCM) boost PFC operation. Its average-current-mode control loop, lack of zero-current detection, and internal compensation structure assume CCM waveforms. Attempting DCM results in unstable regulation, excessive THD, and potential OCP false triggering due to distorted current sensing.