16V active clamp current mode PWM controller with N-channel clamp FET and line OV protection


Product details


Topology Active-Clamp Forward, Flyback, Forward Control method Current Supply voltage (Max) (V) 16 Supply voltage (Min) (V) 8.5 Duty cycle (Max) (%) 100 UVLO thresholds on/off (V) 13.0/8.0 Frequency (Max) (kHz) 1000 Operating temperature range (C) -40 to 85 Gate drive (Typ) (A) 2.5 Features Input Line Monitor, Multi-topology, Programmable Slope Compensation, Soft Start, Soft Switching, Supports NFET Clamp Rating Catalog open-in-new Find other PWM controllers & resonant controllers

Package | Pins | Size

SOIC (D) 16 59 mm² 9.9 x 6 TSSOP (PW) 16 22 mm² 4.4 x 5 open-in-new Find other PWM controllers & resonant controllers


  • Low Output Jitter
  • Soft-Stop Shutdown of MAIN and AUX
  • Ideal for Active Clamp/Reset Forward, Flyback Converters
  • Provides Complementary Auxiliary Driver with Programmable Deadtime (Turn-On Delay) between AUX and MAIN Switches
  • Peak Current-Mode Control with Cycle-by-Cycle Current Limiting
  • 110-V Input Startup Regulator on UCC2891/3
  • TrueDrive™ 2-A Sink, 2-A Source Outputs
  • Accurate Line UV and Line OV Threshold
  • Programmable Slope Compensation
  • 1.0-MHz Synchronizable Oscillator
  • Precise Programmable Maximum Duty Cycle
  • Programmable Soft Start
    • 150-W to 700-W SMPS
    • High-Efficiency, Low EMI/RFI Off-Line or DC/DC Converters
    • Server, 48-V Telecom, Datacom
    • High Power Adapter, LCD-TV and PDP-TV

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The UCC2891/2/3/4 family of PWM controllers is designed to simplify implementation of the various active clamp/reset switching power topologies.

The UCC289x is a peak current-mode, fixedfrequency, high-performance pulse width modulator. It includes the logic and the drive capability for the auxiliary switch with a simple method of programming the critical delays for proper active clamp operation.

The UCC2891/3 includes a 110-V start-up regulator for initial start-up and to provide keep-alive power during stand-by.

Additional features include an internal programmable slope compensation circuit, precise DMAX limit, and a single resistor programmable synchronizable oscillator. An accurate line monitoring function also programs the converter\x92s ON and OFF transitions with regard to the bulk input voltage. Along with the UCC2897, this UCC289x family allows the power supply designer to eliminate many of the external components, reducing the size and complexity of the design.

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Technical documentation

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Type Title Date
* Data sheet UCC289x Current Mode Active Clamp PWM Controller datasheet (Rev. F) Jul. 01, 2009
Application note Understanding and Designing an Active Clamp Current Mode Controlled Converter (Rev. A) Jan. 27, 2020
Selection guide Power Management Guide 2018 (Rev. R) Jun. 25, 2018
Application note Method of Providing Hiccup Operation for UCC2897AEVM Aug. 27, 2009
Application note UCC2891 Active Clamp Dec. 22, 2003
More literature Seminar 1000 Topic 3 - Active Clamp and Reset Technique Feb. 15, 2001
More literature Seminar 1100 Topic 3 - Design Considerations for Active Clamp and Reset Feb. 15, 2001

Design & development

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Design tools & simulation

SLUC118.ZIP (353 KB) - PSpice Model
SLUM154.TSC (834 KB) - TINA-TI Reference Design
SLUM155.ZIP (12 KB) - TINA-TI Spice Model

Reference designs

380VDC Input, 24V/170W Active Clamp Forward Reference Design
PMP7391 This reference design uses the UCC2894 to control an active clamp forward converter that generates an isolated 24 V at 7 A from a 380-VDC input. This supply is intended to be used with a PFC boost front end and requires an external 12-V bias voltage for housekeeping on the primary side. This supply (...)
document-generic Schematic document-generic User guide

CAD/CAE symbols

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SOIC (D) 16 View options
TSSOP (PW) 16 View options

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