STMicroelectronics L4981AD013TR

Overview

L4981AD013TR from STMicroelectronics is a fixed-frequency average-current-mode power factor correction (PFC) controller IC in SO-20 package, designed for boost pre-regulator topologies. It delivers up to 0.99 power factor, limits line current THD to <5%, integrates a ±2% precision 5.1V reference, supports universal AC input (85–265V), and features bipolar/DMOS totem-pole gate driver with >1A peak output for MOSFET/IGBT drive.

For engineers reviewing the L4981AD013TR datasheet, L4981AD013TR pinout, L4981AD013TR application, or L4981AD013TR equivalent, key selection criteria include its fixed-frequency operation (L4981A variant), programmable UVLO threshold, integrated OVP/OCP protection, soft-start timing via external capacitor, and compatibility with continuous-conduction-mode (CCM) boost PFC designs requiring high line regulation and low noise sensitivity.

Technical Context

The L4981AD013TR implements an analog multiplier-based average current mode control architecture, using VRMS, IAC, and LFF inputs to generate a sinusoidal current reference proportional to line voltage and load. Its internal error amplifier compares boost output voltage against a stable 5.1V reference, while the current amplifier regulates sensed inductor current to match that reference without slope compensation.

It operates at a nominal 100 kHz switching frequency set by ROSC/COSC, with oscillator stability of ±20 kHz over temperature and supply variations. The device includes dedicated pins for programmable UVLO (Pin 15), overvoltage protection (Pin 3), peak current limiting (Pin 2), and synchronous clock output (Pin 16), enabling precise system-level timing coordination and robust fault handling in offline AC-DC front-ends.

Key Specifications

Pinout & Package

Package: SO-20 (SOIC-20, 0.300" wide), compliant with JEDEC MS-013, 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 UCC28070PW and FAN4803SJX, the L4981AD013TR offers superior integration (on-chip 5.1 V reference, LFF/VRMS inputs, 1 A gate driver), tighter THD control (<5%), and simpler board layout-making it optimal for industrial and medical 200–400 W PFC stages where reliability and regulatory compliance are critical.

Availability

L4981AD013TR is available at Aetrix Electronics and suitable for server power supplies, industrial motor drives, medical imaging systems, and outdoor LED lighting requiring stable component supply and long-term manufacturability.

Supply support for L4981AD013TR 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 high-efficiency, continuous-conduction-mode boost pre-regulators in universal-input AC-DC power supplies.

FAQ

What is the maximum recommended operating ambient temperature for L4981AD013TR?

The L4981AD013TR is rated for operation from –40°C to +125°C ambient temperature. At 70°C ambient, its SO-20 package has a thermal resistance of 120°C/W; derating is required above this point to maintain junction temperature ≤150°C. Maximum power dissipation drops to 0.6 W at 70°C, limiting total internal losses in high-power designs.

Can L4981AD013TR be used in discontinuous conduction mode (DCM)?

No-L4981AD013TR is explicitly designed for continuous conduction mode (CCM) boost PFC operation. Its average current mode control architecture, lack of zero-current detection, and fixed-frequency oscillator are optimized for CCM. Using it in DCM results in unstable current regulation, poor PF, and potential overcurrent faults due to uncontrolled peak currents.

How is the soft-start time calculated for L4981AD013TR?

Soft-start time is determined by CSS (capacitor on Pin 12) and the internal 100 µA current source: t_SS ≈ (CSS × 5.1 V) / 100 µA. For example, a 1 µF capacitor yields ~51 ms ramp time to full output. The internal discharge MOSFET resets CSS during UVLO or OVP events, ensuring controlled restart after faults.

Does L4981AD013TR support frequency synchronization with external clocks?

Yes-Pin 16 (SYNC) functions as both input and output. As SYNC input, it accepts CMOS-level rectangular waves (min. pulse width 0.3 µs) to lock internal oscillator frequency. As SYNC output, it delivers a 50% duty-cycle clock pulse train synchronized to internal switching, enabling multi-controller coordination without external logic.