TI UCC28251PW

The UCC28251 PWM controller is designed for high power density applications with stringent pre-bias startup requirements. The UCC28251's integrated synchronous rectifier control outputs target high-efficiency, high-performance topologies such as half-bridge, full-bridge, interleaved forward, and push-pull. The UCC27210 half-bridge driver and UCC2752x MOSFET drivers used with the UCC28251 provide a complete power converter solution. The combination of an externally programmable soft-start with the internal pre-bias startup circuit allows the controller to gradually reach its steady-state operating point under all output conditions. The UCC28251 can be configured for primary- or secondary-side control and supports both voltage-mode and current-mode control. The oscillator operates at frequencies up to 1.8 MHz and can synchronize to an external clock. Input voltage feed-forward, cycle-by-cycle current limiting, and a programmable hiccup timer keep the system within a safe operating range. Input voltage, output voltage, and temperature protections are supported. Dead times between primary-side switches and secondary-side synchronous rectifiers can be set independently.

• Pre-biased startup
• Synchronous rectifier control output with programmable delay (including zero-delay support)
• Voltage mode control or current mode control with input voltage feedforward
• Primary-side or secondary-side control
• 3.3V, 1.5% high-accuracy reference output
• Lower minimum operating frequency
• 1% high-accuracy cycle-by-cycle overcurrent protection with matched duty cycle outputs
• Programmable soft-start and hiccup restart timer
• Thermally enhanced 4mm × 4mm ultra-thin VQFN-20 package and 20-pin TSSOP package

• Half-bridge, full-bridge, interleaved forward, and push-pull isolated converters
• Telecom and data communication power supplies
• Wireless base station power supplies
• Server power supplies
• Industrial power systems