UCC2897A 110-V active clamp current mode PWM controller with P-channel clamp FET and line OV protection | TI.com

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



The UCC2897A PWM controller simplifies implementation of the various active clamp or reset and synchronous rectifier switching power topologies.

The UCC2897A is a peak current-mode fixed-frequency high-performance pulse-width modulator. The controller 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 ON and OFF transitions of the converter with regard to the bulk input voltage, VIN.

The UCC2897A adds a second-level hiccup-mode current-sense threshold, bi-directional synchronization and input-overvoltage protection functionalities. The UCC2897A is offered in 20-pin TSSOP (PW) and 20-pin QFN (RGP) packages.


  • Low-output jitter
  • Soft-stop shutdown of MAIN and AUX
  • 110-V input startup function
  • Ideal for active-clamp, reset-forward, flyback and synchronous rectifier uses
  • Provides complementary auxiliary driver with programmable dead time (Turn-On Delay) between AUX and MAIN switches
  • Peak current-mode control with 0.5-V cycle-by-cycle current limiting
  • TrueDrive™ 2-A Sink, 2-A source outputs
  • Trimmed internal-bandgap reference for accurate line UV and line OV threshold
  • Programmable slope compensation
  • High-performance 1-MHz synchronizable oscillator with internal timing capacitor
  • Precise programmable maximum duty cycle
  • PB-free lead finish package

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  Min   Max Range
Vin  V 18.0 to 110.0V
Vout  V 3.3 to 50V
Iout  A ≤ 100A
Ambient Temp  °C -40 to 125°C


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Part number Order Topology Control method VCC (Min) (V) VCC (Max) (V) Frequency (Max) (kHz) UVLO thresholds on/off (V) Duty cycle (Max) (%) Gate drive (Typ) (A) Features Rating Operating temperature range (C) Package Group Package size: mm2:W x L (PKG)
UCC2897A Order now Active-Clamp Forward
Current     8.5     16     1000     12.7/~8     74     2     HV Start-up
Input Line Monitor
Programmable Slope Compensation
Soft Start
Soft Switching
Supports PFET Clamp    
Catalog     -40 to 125     QFN | 20
TSSOP | 20    
20QFN: 16 mm2: 4 x 4 (QFN | 20)
20TSSOP: 42 mm2: 6.4 x 6.5 (TSSOP | 20)    
LM5026 Order now Active-Clamp Forward
Current     8     15     1000     Programmable/1.25V     80     3     Current Limiting
Dead Time Control
HV Start-up
Leading Edge Blanking
Programmable Max Duty Cycle
Programmable Soft Start
Supports NFET Clamp
Supports PFET Clamp
Synchronization Pin    
Catalog     -40 to 125     TSSOP | 16
WSON | 16    
16TSSOP: 22 mm2: 4.4 x 5 (TSSOP | 16)
16WSON: 25 mm2: 5 x 5 (WSON | 16)    
LM5034 Order now Active-Clamp Forward
Current     8     15     2000     Programmable/1.25V     76     2.5     Current Limiting
HV Start-up
Soft Start
Supports PFET Clamp
Synchronization Pin    
Catalog     -40 to 125     TSSOP | 20     20TSSOP: 42 mm2: 6.4 x 6.5 (TSSOP | 20)