The UCC28250 PWM controller is designed for high power density applications that may have stringent prebiased start-up requirements. The integrated synchronous rectifier control outputs target high-efficiency and high-performance topologies such as half-bridge, full-bridge, interleaved forward, and push-pull. The UCC27200 half-bridge drivers and UCC2732X MOSFET drivers used in conjunction with the UCC28250 provide a complete power converter solution.
Externally programmable soft-start, used in conjunction with an internal prebiased start-up circuit, allows the controller to gradually reach a steady-state operating point under all output conditions. The UCC28250 can be configured for primary or secondary-side control and either voltage or current mode control can be implemented.
The oscillator operates at frequencies up to 2 MHz, and can be synchronized to an external clock. Input voltage feedforward, cycle-by-cycle current limit, and a programmable hiccup timer allow the system to stay within a safe operation range. Input voltage, output voltage and temperature protection can be implemented. Dead time between primary-side switch and secondary-side synchronous rectifiers can be independently programmed.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
UCC28250 | TSSOP (20) | 6.50 mm × 4.40 mm |
VQFN (20) | 4.00 mm × 3.50 mm |
Changes from C Revision (July 2011) to D Revision
Changes from B Revision (October 2010) to C Revision
Changes from A Revision (April, 2010) to B Revision
PIN | I/O | DESCRIPTION | ||
---|---|---|---|---|
NAME | QFN | PW | ||
COMP | 3 | 10 | I/O | Error amplifier output |
EN | 18 | 5 | I | Device enable and disable |
FB/EA- | 2 | 9 | I | Error amplifier inverting input |
GND | 4 | 11 | I | Ground |
HICC | 10 | 17 | I | Cycle-by-cycle current limit time delay and Hiccup time setting |
ILIM | 17 | 4 | I | Current sense for cycle-by-cycle overcurrent protection |
OUTA | 9 | 16 | O | 0.2-A sink/source primary switching output |
OUTB | 8 | 15 | O | 0.2-A sink/source primary switching output |
OVP/OTP | 19 | 6 | I | Overvoltage and overtemperature protection pin |
PS | 11 | 18 | I | Primary off to synchronous rectifier on dead-time set |
RAMP/CS | 16 | 3 | I | PWM ramp input (for voltage mode control) or current sense input (for current mode control) |
REF/EA+ | 1 | 8 | I | Error amplifier noninverting input |
RT | 15 | 2 | I | Oscillator frequency set or synchronous clock input |
SP | 12 | 19 | I | Synchronous rectifier off to primary on dead-time set |
SRA | 7 | 14 | O | 0.2-A sink/source synchronous rectifier output |
SRB | 6 | 13 | O | 0.2-A sink/source synchronous rectifier output |
SS | 13 | 20 | I/O | Soft-start programming |
VDD | 5 | 12 | I | Bias supply input |
VREF | 20 | 7 | O | 3.3-V reference output |
VSENSE | 14 | 1 | I | Output voltage sensing for prebias control |