Features: · 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 Cycle-by-Cycle Current Limiting
· TrueDrive 2-A Sink, 2-A Source Outputs
· 110-V Input Startup Device on UCC2891/3
· 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 Limit
Application· High-Efficiency Off-Line or DC/DC Switch-Mode Power Supplies
· Server Power, 48-V Telecom, Datacom, and 42-V Automotive ApplicationsPinout
SpecificationsSupply voltage range, VDD (IDD < 10 mA) .....................................................15 V
Analog inputs FB, CS ................................−0.3 to (VREF + 0.3) not to exceed 6 V
Output source current (peak), IO SOURCE OUT, AUX ...................................2.5 A
Output sink current (peak), IO SINK OUT, AUX ...........................................−2.5 A
Operating junction temperature range, TJ .....................................−55 to 150 °C
Storage temperature, Tstg .............................................................−65 to 150 °C
Lead temperature, Tsol, 1,6 mm (1/16 inch) from case for 10 seconds ......300 °C
DescriptionThe UCC2891/2/3/4 family of PWM controllers is designed to simplify implementation of the various active clamp/reset and synchronous rectifier 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 along with a simple method of programming the critical delays for proper active clamp operation.
Additional features of UCC2891/2/3/4 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. These features allow the power supply designer to eliminate many of the external components, reducing the size and complexity of the design.
The devices UCC2891/2/3/4 are offered in 16-pin SOIC (D). The UCC2892 and UCC2894 is also offered in 16-pin TSSOP (PW) packages.
UCC2891 Data Sheet
