UCC28528 Datasheet | Texas Instruments

FEATURES D Provides Control of PFC and PWM Power Stages In One Device D Trailing-Edge PFC, Trailing-Edge PWM Modulation D Built-In Sequencing of PFC and PWM Turn-On D 2-A Source and 3-A Sink Gate Drive for Both PFC and PWM Stages D Typical 16-ns Rise Time and 7-ns Fall Time into 1-n F Loads PFC Features - Average-Current-Mode Control for Continuous Conduction Mode Operation - Highly-Linear Multiplier for Near-Unity Power Factor - Input Voltage Feedforward Implementation - Improved Load Transient Response - Accurate Power Limiting - Zero Power Detect PWM Features - Peak-Current-Mode Control Operation - 1:1 PFC:PWM Frequency Option - Programmable maximum Duty Cycle Limit Up to 90% - Programmable Soft-Start APPLICATIONS D High-Efficiency Server and Desktop Supplies D High-Efficiency Tele AC-DC Converter DESCRIPTION The UCC28521 and UCC28528 bination PFC/PWM controllers provide plete control functionality for any off-line power system requiring pliance with the IEC1000- 3- 2 harmonic reduction requirements. By bining the control and drive signals for the PFC and the PWM stages into a single device, significant performance and cost benefits are gained. Based on the UCC28511, the new devices employ an average current mode control architecture with input voltage feedforward. The major difference of the UCC28521/28 is the trailing-edge / trailing-edge (TEM/TEM) modulation scheme for the PFC/PWM stages. The UCC28528 differs from the UCC28521 as its PWM stage does not turn off with the falling bulk voltage. The UCC28528 PWM was designed for low power auxiliary supplies. These devices offer performance advantages over earlier generation bination controllers. A key PWM feature is programmable maximum duty cycle. For the PFC stage, the devices feature an improved multiplier and the use of a transconductance amplifier for enhanced transient response. The core of the PFC section is in a three-input multiplier that generates the reference signal for the line current. The UCC28521/28...