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| TI UCC28230 PWM总线控制方案 | |||||
作者：TI 文章来源：TI 点击数： 更新时间：2008-6-16  |
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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 as 120-V high-side/low-side driver UCC27200, can be used with this controller. Low cost, small size and highly efficient solutions are achieved by innovations such as: Start-up frequency control circuit allowing small output inductor and start with large intermediate bus capacitance. Load dependent 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 programmable time the controller proceeds into periodical shutdown and restart hiccup mode. The UCC28230 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 shutdown, programmable soft-start, over-current hiccup mode and short circuit protection with internal restart (by default) or latch-off mode by using an external resistor.  主要特性: Programmable, Load Dependent, 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 x 2 mm SON-12 and TSSOP-14 Package Options 应用: Intermediate Bus Isolated Converters DC-to-DC Transformers  图1.全桥转换器电路  图2.半桥转换器电路 详情请见: http://focus.ti.com/lit/ds/symlink/ucc28230.pdf |
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