The UCC28230, UCC28231 PWM bus controllers are optimized for use in high efficiency, high power density, unregulated intermediate bus converters. Topologies include push-pull, half-bridge and full-bridge. External drivers, such asthe UCC27200 120-V high-side/low-side drivers, can be used with this controller.
Low cost, small size and highly efficient solutions are provided by innovations such as:
- Start-up frequency control circuit allowing small output inductor andthe ability tostart with large intermediate bus capacitor.
- Load depended off-time control set by user.
Additional 1-D control outputs can be used for primary winding clamping in self-driven output synchronous rectifier applications or as drive signals for the control-driven synchronous rectifier.
Cycle-by-cycle current limit prevents overstresses of converter. If the over current condition causes less than 80% duty cycle at the output, then after a programmed time the controller proceeds into periodical shutdown and restart hiccup mode.
The UCC28230PWR provides 5 V, and the UCC28231 provides 3.3-V precision reference voltages with 1.5% overall accuracy and 10-mA output current. This reference voltage can be used to supply housekeeping circuit and/or microcontroller. The precision reference voltage can also be used for accurate setting of system parameters.
Other features include under-voltage lockout, thermal shut down, programmable soft start, over-current hiccup mode and short circuit protection with internal restart by default that can be set into latch-off mode by an external resistor.
Feature
- Programmable, Load Depended Off Time Control
- Frequency Controlled Start Up Allows Small Output Inductor, Low Ripple and Constant Current Start with Large Output Capacitor
- Two 0.2-A Push-Pull Outputs Provide Matched Control Signals D to External Drivers
- Two Additional 1- D Outputs for Optimal Use of Self-Driven or Control Driven Synchronous Rectifiers
- Unregulated, Fixed Volt-Second or Fixed Frequency Modes set by User
- Two, 1.5% Overall Accuracy Reference Voltage Options: 5-V for UCC28230 and 3.3-V for UCC28231
- Resistor Programmable Switching Frequency up to 1 MHz
- Cycle-by-Cycle Current Limit Allows Parallel Operation with Droop Based Current Sharing
- Single External Capacitor sets Soft-Start and Over Current Hiccup Mode Parameters with Restart
- Severe Short Circuit Hiccup with Restart or Latch Off Protection Option by External Resistor
- Input Under Voltage Lock Out
- Thermal Shutdown
- Thermally Enhanced 3 mm × 2 mm SON-12 and TSSOP-14 Package Options
- APPLICATIONS
- Intermediate Bus Isolated Converters
- DC-to-DC Transformers
