TI TPS54383双路异步转换器应用方案
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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