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UCC2897

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Current Mode Active Clamp PWM Controller

UCC2897 is in the process of being discontinued
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UCC2897A ACTIVE 110-V active clamp current mode PWM controller with P-channel clamp FET and line OV protection This product is a replacement device for 0 to 70 degrees C. Designs can achieve better performance.

Product details

Switching frequency (max) (kHz) 1000 UVLO thresholds on/off (V) 13/8 Operating temperature range (°C) -40 to 105 Rating Catalog
Switching frequency (max) (kHz) 1000 UVLO thresholds on/off (V) 13/8 Operating temperature range (°C) -40 to 105 Rating Catalog
TSSOP (PW) 20 41.6 mm² 6.5 x 6.4
  • Ideal for Active Clamp/Reset Forward, Flyback and Synchronous Rectifier Apps
  • Provides Complementary Auxiliary Driver with Programmable Deadtime (Turn-On Delay) between AUX and MAIN Switches
  • Peak Current-Mode Control with 0.5-V Cycle-by-Cycle Current Limiting
  • Hiccup Mode 0.75-V Current Limit
  • TrueDrive™ 2-A Sink, 2-A Source Outputs
  • 110-V Input Startup Device
  • Trimmed Internal Bandgap Reference for Accurate Line UV and Line OV Threshold
  • Programmable Slope Compensation
  • High-Performance 1.0-MHz Synchronizable Oscillator with Internal Timing Capacitor
  • Precise Programmable Maximum Duty Cycle
  • PB-Free Lead Finish Package
  • APPLICATIONS
    • High-Efficiency DC/DC Power Supplies
    • Server Power, 48-V Telecom, Datacom, and 42-V Automotive Applications

  • Ideal for Active Clamp/Reset Forward, Flyback and Synchronous Rectifier Apps
  • Provides Complementary Auxiliary Driver with Programmable Deadtime (Turn-On Delay) between AUX and MAIN Switches
  • Peak Current-Mode Control with 0.5-V Cycle-by-Cycle Current Limiting
  • Hiccup Mode 0.75-V Current Limit
  • TrueDrive™ 2-A Sink, 2-A Source Outputs
  • 110-V Input Startup Device
  • Trimmed Internal Bandgap Reference for Accurate Line UV and Line OV Threshold
  • Programmable Slope Compensation
  • High-Performance 1.0-MHz Synchronizable Oscillator with Internal Timing Capacitor
  • Precise Programmable Maximum Duty Cycle
  • PB-Free Lead Finish Package
  • APPLICATIONS
    • High-Efficiency DC/DC Power Supplies
    • Server Power, 48-V Telecom, Datacom, and 42-V Automotive Applications

The UCC2897 PWM controller simplifies implementation of the various active clamp/reset and synchronous rectifier switching power topologies.

Based on the UCC2891 active-clamp controller the UCC2897 is a peak current-mode, fixed-frequency, high-performance pulse width modulator. It includes the logic and the drive capability for the P-channel auxiliary switch along with a simple method of programming the critical delays for proper active clamp operation.

Features include an internal programmable slope compensation circuit, precise DMAX limit, and a synchronizable oscillator with an internal timing capacitor. An accurate line monitoring function also programs the converter's ON and OFF transitions with regard to the bulk input voltage.

The UCC2897 adds a second level hiccup mode current sense threshold, bi-directional synchronization and the input overvoltage protection functionalities that are not available on the 16-pin UCC2891. The UCC2897 is offered in 20-pin TSSOP (PW) and 20-pin QFN (RTJ) package.

The UCC2897 PWM controller simplifies implementation of the various active clamp/reset and synchronous rectifier switching power topologies.

Based on the UCC2891 active-clamp controller the UCC2897 is a peak current-mode, fixed-frequency, high-performance pulse width modulator. It includes the logic and the drive capability for the P-channel auxiliary switch along with a simple method of programming the critical delays for proper active clamp operation.

Features include an internal programmable slope compensation circuit, precise DMAX limit, and a synchronizable oscillator with an internal timing capacitor. An accurate line monitoring function also programs the converter's ON and OFF transitions with regard to the bulk input voltage.

The UCC2897 adds a second level hiccup mode current sense threshold, bi-directional synchronization and the input overvoltage protection functionalities that are not available on the 16-pin UCC2891. The UCC2897 is offered in 20-pin TSSOP (PW) and 20-pin QFN (RTJ) package.

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Technical documentation

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Type Title Date
* Data sheet Advanced Current-Mode Active Clamp PWM Controller datasheet (Rev. G) 17 Dec 2008
More literature Исходные проекты ll 13 May 2011
User guide Reference Design PR265A (Rev. A) 01 Apr 2004
Application note UCC2891 Active Clamp 22 Dec 2003
More literature Seminar 1000 Topic 3 - Active Clamp and Reset Technique 15 Feb 2001
More literature Seminar 1100 Topic 3 - Design Considerations for Active Clamp and Reset 15 Feb 2001

Design & development

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Reference designs

PMP8923 — Non-Standard PoE (>25.5W) - High Efficiency Forward Converter (5V@10A) Reference Design

This converter provides a high power PoE output of 5V/10A. The TPS2379 PD controller allows the use of an external hot swap FET for increased efficiency. The UCC2897A PWM controller is used to implement a high efficiency active clamp forward converter.
Test report: PDF
Schematic: PDF
Package Pins Download
TSSOP (PW) 20 View options

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