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| TI UCC28230 PWM总线控制方案 |
| 作者： 时间：2008-07-10 来源:eaw |
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TI公司的UCC28230和UCC28231 PWM总线控制器具有根据负载进行编程的特性,频率控制的起动允许使用较小的输出电感和低的波纹,而恒流起动则采用大输出电容,效率高达97%. UCC28230/1包括了推挽,半桥和全桥托扑电路,能和外接驱动器如120V高边/低边驱车器UCC27200配合使用.因此,非常适合用在高效率,高功率密度和不调整的中间总线转换器以及DC-DC变压器.本文介绍了UCC28230和UCC28231的主要特性以及全桥转换器和半桥转换器的电路图.
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
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