| TPS54383双路异步转换器应用方案(TI) |
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| 作者:TI 来源:本站原创 点击数:129 更新时间:2008-3-17 |
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TI公司的TPS54383 和TPS54386是双输出异步降压DC/DC转换器,输入电压从4.5V到28V,输出电流可高达3A,输出电压则在0.8V和输入电压的90%之间.主要应用在机顶盒,数字TV,DSP电源和消费类电子产品.本文介绍了TPS54383 和TPS54386的主要性能,功能方框图以及多种详细的设计案例.
TI 3-A DUAL NON-SYNCHRONOUS CONVERTER WITH INTEGRATED HIGH-SIDE MOSFET The TPS54383 and TPS54386 are dual output, non-synchronous buck converters capable of supporting 3-A output applications that operate from a 4.5-V to 28-V input supply voltage, and require output voltages between 0.8 V and 90% of the input voltage.
With an internally-determined operating frequency, soft start time, and control loop compensation, these converters provide many features with a minimum of external components. Channel 1 overcurrent protection is set at 4.5 A, while Channel 2 overcurrent protection level is selected by connecting a pin to ground, to BP, or left floating. The setting levels are used to allow for scaling of external components for applications that do not need the full load capability of both outputs.
The outputs may be enabled independently, or may be configured to allow either ratiometric or sequential startup sequencing. Additionally, the two outputs may be powered from different sources.

主要特性: 4.5-V to 28-V Input Range Output Voltage Range 0.8 V to 90% of Input Voltage Output Current Up to 3 A Two Fixed Switching Frequency Versions: TPS54383: 300 kHz TPS54386: 600 kHz Three Selectable Levels of Overcurrent Protection (Output 2) 0.8-V 1.5% Voltage Reference 2.1-ms Internal Soft Start Dual PWM Outputs 180° Out-of-Phase Ratiometric or Sequential Startup Modes Selectable by a Single Pin 85-m Internal High-Side MOSFETs Current Mode Control Internal Compensation (See Page 16) Pulse-by-Pulse Overcurrent Protection Thermal Shutdown Protection at +148°C 14-Pin PowerPAD™ HTSSOP package 应用: Set Top Box Digital TV Power for DSP Consumer Electronics

图1. TPS54383/6方框图。
设计案例: 案例1: 12-V 到5-V 和3.3-V转换器的详情设计 The following example illustrates a design process and component selection for a 12-V to 5-V and 3.3-V dual non-synchronous buck regulator using the TPS54383 converter.

表1.设计案例所用元件清单(BOM)

案例2: 24-V到12-V 以及24-V 到5-V转换器详细设计 For a higher input voltage, both a snubber and bootstrap resistors are added to reduce ringing on the switch node and a 30 V schottky diode is selected. A higher resistance feedback network is chosen for the 12 V output to reduce the feedback current.

案例3: 5-V 到3.3V 以及5-V 到1.2 V详细设计 For a low input voltage application, the TPS54386 is selected for reduced size and all ceramic output capacitors are used. 22-F input capacitors are selected to reduce input ripple and lead capacitors are placed in the feedback to boost phase margin.
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