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UCC2891

ACTIVE

110-V active clamp current mode PWM controller with P-channel clamp FET and 0.75V CS threshold

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Data sheet

UCC2891

ACTIVE
Data sheet Order now

Product details

Topology Active-clamp forward, Flyback, Forward Control mode Current Features High-voltage startup, Input line monitor, Multi-topology, Programmable slope compensation, Soft start, Soft switching, Supports NFET clamp Duty cycle (max) (%) 100
Topology Active-clamp forward, Flyback, Forward Control mode Current Features High-voltage startup, Input line monitor, Multi-topology, Programmable slope compensation, Soft start, Soft switching, Supports NFET clamp Duty cycle (max) (%) 100
TSSOP (PW) 16 32 mm² (5 mm × 6.4 mm) SOIC (D) 16 59.4 mm² (9.9 mm × 6 mm)
  • 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
  • APPLICATIONS
    • 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
  • 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
  • APPLICATIONS
    • 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

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.

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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UCC2897A ACTIVE 110-V active clamp current mode PWM controller with P-channel clamp FET and line OV protection Supports active clamp topology

Technical documentation

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Top documentation Type Title Format options Date
* Data sheet UCC289x Current Mode Active Clamp PWM Controller datasheet (Rev. F) Jul 1, 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
Analog design Journal Design of a 60-A interleaved active-clamp forward converter Jan 22, 2013
Analog design Journal 1Q 2013Issue Analog Applications Journal Jan 22, 2013
User guide 48-V to 3.3-V Forward Converter w/Active Clamp Reset Using the UCC2891 Active Cl (Rev. A) Apr 13, 2012
Application note Method of Providing Hiccup Operation for UCC2897AEVM Aug 27, 2009
User guide 48-V to 3.3-V Forward Converter w/Active Clamp Reset (Rev. A) Dec 12, 2006
Application note Active Clamp Transformer Reset: High Side or Low Side? Sep 17, 2004
Application note UCC2891 Active Clamp Dec 22, 2003
More literature Seminar 1100 Topic 3 - Design Considerations for Active Clamp and Reset Feb 15, 2001
More literature Seminar 1000 Topic 3 - Active Clamp and Reset Technique Feb 15, 2001

Design & development

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

Evaluation board

UCC2891EVM-520 — Evaluation Module for UCC2891 Current Mode Active Clamp PWM Controller

The UCC2891EVM evaluation module (EVM) is a forward converter providing a 3.3V regulated output at 30A of load current, operating from a 48V input. The EVM operates over the full 36V to 75V telecom input range, and is able to fully regulate down to zero load current. The module uses the UCC2891 (...)
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Simulation model

UCC2891 TINA-TI Startup Reference Design

SLUM294.TSC (667 KB) - TINA-TI reference design
Supported products & hardware
Simulation model

UCC2891 TINA-TI Steady State Reference Design

SLUM292.TSC (183 KB) - TINA-TI reference design
Supported products & hardware
Simulation model

UCC2891 TINA-TI Transient Spice Model

SLUM293.ZIP (42 KB) - TINA-TI Spice model
Supported products & hardware
Simulation model

UCC2891 Unencrypted PSpice Transient Model Package (Rev. A)

SLVM050A.ZIP (117 KB) - PSpice model
Supported products & hardware
Simulation model

UCC289x PSpice Average Model

SLUC118.ZIP (353 KB) - PSpice model
Supported products & hardware
Simulation model

UCC289x TINA-TI Average Reference Design

SLUM154.TSC (834 KB) - TINA-TI reference design
Supported products & hardware
Simulation model

UCC289x TINA-TI Average Spice Model

SLUM155.ZIP (12 KB) - TINA-TI Spice model
Supported products & hardware
Package Pins CAD symbols, footprints & 3D models
TSSOP (PW) 16 Ultra Librarian
SOIC (D) 16 Ultra Librarian
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