UCC2897A Electronic IC Chips microchips and integrated circuits

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UCC2897A

ADVANCED CURRENT-MODE ACTIVE CLAMP PWM CONTROLLER

FEATURES

• Low Output Jitter
• “Soft Stop” shut down 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 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^TM 2-A Sink, 2-A Source Outputs
  

• Trimmed Internal Bandgap Reference for Accurate Line UV and Line OV Threshold
  
• Programmable Slope Compensation
  
• High-Performance 1.0-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

DESCRIPTION

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

The UCC2897A is a peak current-mode, fixedfrequency, 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 D_MAX 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, 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) package.

ABSOLUTE MAXIMUM RATINGS

over operating free-air temperature range unless otherwise noted(1)

(1) Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltages are with respect to GND. Currents are positive into and negative out of, the specified terminal.

TYPICAL APPLICATION DIAGRAM