90V active clamp voltage mode PWM controller with P or N-channel clamp FET and 0.5V CS threshold


Product details


Topology Active-Clamp Forward, Forward Control method Feedforward, Voltage VCC (Min) (V) 8 VCC (Max) (V) 15 Duty cycle (Max) (%) 80 UVLO thresholds on/off (V) Programmable/2.5V Frequency (Max) (kHz) 1000 Operating temperature range (C) -40 to 125 Gate drive (Typ) (A) 3 Features Current Limiting, HV Start-up, Leading Edge Blanking, Soft Start, Supports NFET Clamp, Supports PFET Clamp, Thermal Shutdown Rating Catalog open-in-new Find other PWM controllers & resonant controllers

Package | Pins | Size

TSSOP (PW) 16 22 mm² 5 x 4.4 WSON (NHQ) 16 25 mm² 5 x 5 open-in-new Find other PWM controllers & resonant controllers


  • Internal Start-Up Bias Regulator
  • 3-A Compound Main Gate Driver
  • Programmable Line Undervoltage Lockout (UVLO) With Adjustable Hysteresis
  • Voltage Mode Control With Feedforward
  • Adjustable Dual Mode Overcurrent Protection
  • Programmable Overlap or Dead Time Between the Main and Active Clamp Outputs
  • Volt × Second Clamp
  • Programmable Soft Start
  • Leading Edge Blanking
  • Single Resistor Programmable Oscillator
  • Oscillator UP and DOWN Sync Capability
  • Precision 5-V Reference
  • Thermal Shutdown
  • Packages:
    • 16-Pin TSSOP
    • Thermally Enhanced 16-Pin WSON (5 mm × 5 mm)
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The LM5025A is a functional variant of the LM5025 active clamp PWM controller. The functional differences of the LM5025A are that the CS1 and CS2 current limit thresholds have been increased to 0.5 V, the internal CS2 filter discharge device has been disabled and no longer operates each clock cycle, and the internal VCC and VREF regulators continue to operate when the line UVLO pin is below threshold.

The LM5025A PWM controller contains all of the features necessary to implement power converters using the Active Clamp / Reset technique. With the active clamp technique, higher efficiencies and greater power densities can be realized compared to conventional catch winding or RDC clamp / reset techniques. Two control outputs are provided: the main power switch control (OUT_A) and the active clamp switch control (OUT_B). The two internal compound gate drivers parallel both MOS and bipolar devices, providing superior gate drive characteristics. This controller is designed for high-speed operation including an oscillator frequency range up to 1 MHz and total PWM and current sense propagation delays less than 100 ns. The LM5025A includes a high-voltage start-up regulator that operates over a wide input range of 13 V to 90 V. Additional features include: line undervoltage lockout (UVLO), soft start, oscillator UP and DOWN sync capability, precision reference, and thermal shutdown.

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Technical documentation

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No results found. Please clear your search and try again. View all 5
Type Title Date
* Datasheet LM5025A Active Clamp Voltage Mode PWM Controller datasheet (Rev. F) Aug. 18, 2016
Technical articles Excuse me for being a little forward... with my topology Oct. 21, 2015
Technical articles MHz isolated power supply - we are at the inflection point Dec. 14, 2013
User guides LM5025 Isolated Active Clamp Forward Converter Ref Design User Guide Jan. 27, 2012
Application notes Operation and Benefits of Active-Clamp Forward Power Converters Mar. 22, 2007

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Hardware development

document-generic User guide

The LM5025A evaluation board is designed to provide the design engineer with a fully functional power converter based on the Active Clamp Forward topology to evaluate the LM5025A controller. The evaluation board is provided in an industry standard half-brick footprint.

  • Internal Start-up Bias Regulator
  • 3 A Compound Main Gate Driver
  • Programmable Line Under-Voltage Lockout (UVLO) with Adjustable Hysteresis
  • Voltage Mode Control with Feed-Forward
  • Adjustable Dual Mode Over-Current Protection
  • Programmable Overlap or Deadtime between the Main and Active Clamp Outputs
  • Volt x (...)

Design tools & simulation

SNVM477A.ZIP (48 KB) - PSpice Model
SLUC655.ZIP (184 KB)

Reference designs

18V-36Vdc Input, 5V/30W Active Clamp Forward - Reference Design
PMP4468 The PMP4468 is a DC-DC isolated module reference design targeted for industrial and telecom applications. The DC input range is 18V-36V, with 24V typical and the output is 5V/6A. An active clamp forward controller LM5025A is used in the design. The efficiency is up to 90% with good thermal (...)
document-generic Schematic document-generic User guide
18-40Vin Isolated 5V/6A Power Supply with Low Profile for Industrial Application Reference Design
PMP4428 This 5V / 6A  solution implements a high efficiency active clamp controller LM5025A and self-drive synchronous rectifier. Input voltage is 18V-40V as typical industrial request and efficiency is 89.5%@24Vin full load. The transformer is embeded into the PCB and 8mm height can be met. The design (...)
document-generic Schematic document-generic User guide
Isolated Forward Converter Reference Design
PMP7806 — The PMP7806 reference design is a Forward which uses a LM5025A and was intended for Metering applications. It can generate an Isolated 15 volt output at 3 Amps from an input 16 to 32 Volts DC.
Design files
Active clamp forward with -30 to -6V input and 6V @ 18A output
PMP7756 — PMP7756 is an active clamp forward controller. It has a 6V @ 18A isolated output. It uses self driven synchronous regulation.
Design files

CAD/CAE symbols

Package Pins Download
TSSOP (PW) 16 View options
WSON (NHQ) 16 View options

Ordering & quality

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