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[原创] Linear LTC7820大功率无电感电荷泵控制方案

关键词:电源管理 DC/DC转换器 电荷泵 LTC7820

时间:2017-07-11 10:14:05       作者:Linear       来源:中电网

Linear公司的LTC7820是固定比例高压大电流开关电容/电荷泵控制器,包括了四个N沟MOSFET栅极驱动器,用来驱动电压分压器,倍增器反相器的外接功率MOSFET.器件降压比例2:1,输入电压高达72V;升压比例会1:2,输入电压高达36V或反相器比例1:1,输入电压高达36V.工作频率100kHz 到1MHz,主要用在总线转换器,大功率分布式电源系统,通信系统和工业应用.本文介绍了LTC7820主要特性,框图,多种应用电路以及演示板2543A主要特性和指标,电路图,材料清单和PCB设计图.

The LTCR7820 is a fixed ratio high voltage high powerswitched capacitor/charge pump controller. The deviceincludes four N-channel MOSFET gate drivers to driveexternal power MOSFETs in voltage divider, doubler orinverter configurations. The device achieves a 2:1 stepdownratio from an input voltage as high as 72V, a 1:2step-up ratio from an input voltage as high as 36V, or a1:1 inverting ratio from an input voltage up to 36V. Eachpower MOSFET is switched with 50% duty cycle at aconstant pre-programmed switching frequency. Systemefficiency can be optimized to over 99%. The LTC7820provides a small and cost effective solution for highpower, non-isolated intermediate bus applications withfault protection.

The LTC7820 switching frequency can be linearlyprogrammed from 100 kHz to 1MHz. The device is availablein a thermally enhanced 28-lead QFN package with someno-connect pins for high voltage compatible pin spacing.

LTC7820主要特性:

Low Profile, High Power Density, Capable of 500W+
Soft Switching: 99% Peak Efficiency and Low EMI
VIN Max for Voltage Divider (2:1): 72V
VIN Max for Voltage Doubler (1:2)/Inverter (1:1): 36V
Wide Bias VCC Range: 6V to 72V
Soft Startup into Steady State Operation
6.5V to 40V EXTVCC Input for Improved Efficiency
Input Current Sensing and Overcurrent Protection
Wide Operating Frequency Range: 100kHz to 1MHz
Output Short-Circuit/OV/UV Protections withProgrammable Timer and Retry
Thermally Enhanced 28-Pin 4mm × 5mm QFN Package

LTC7820应用:

Bus Converters
High Power Distributed Power Systems
Communications Systems
Industrial Applications

图1.LTC7820功能框图

图2.LTC7820 PCB大电流布局图

图3.LTC7820高效48V/24V到24V/12V 15A电压分压器电路图

图4.LTC7820带FET输入的高效24V到48V 7.5A电压倍压器电路图

图5.LTC7820输入热插拔的高效24V到-24V 10A电压反相器电路图

图6.LTC7820输入热插拔的高效24V到12V 10A电压分压器电路图

图7.LTC7820高效48V到12V 20A电压分压器电路图

演示板2543A

Demonstration circuit 2543A is a high efficiency, highdensity, open loop charge pump (inductorless) DC/DCconverter. This demo board is a voltage divider whichachieves a 2:1 step-down ratio from an input voltage from36V to 60V. The output voltage is a fixed ratio of half of theinput voltage (VIN/2) and can supply a 10A load current.This demo board has the option to deliver a 20A maximumload with the addition of 15 chip capacitors.

The DC2543A provides a very high efficiency solution of98.7% when converting 48VIN to 24VOUT at 10A as shownin Figure 3. When configured for a 20A output, an efficiencyof up to 98.4% is achievable for a 48VIN to 24VOUTat 20A as shown in Figure 8.

The demo board features the LTC®7820, a fixed ratio highvoltage high power switched capacitor/charge pumpcontroller in a 4mmx 5mm QFN package. Please seeLTC7820 data sheet for more detailed information.The DC2543A needs to be powered on with no load currentor a very small load current (less than 50mA) with thedefault setup. Large load current can be applied after VOis established. The board offers a disconnect FET optionwhich is controlled by the LTC7820 FAULT pin to disconnectthe load during startup as shown in the schematic.

Please refer to “Voltage Divider PrebalanceBefore Switching”section in the LTC7820 data sheet for more detailsregarding the startup of the voltage divider. The board also features some protection functions such as overcurrentand thermal shutdown to make it a reliable solution.

Performance Summary The DC2543A needs to be powered on with no load currentor a very small load current (less than 50mA) with thedefault setup. Large load current can be applied after VOis established. The board offers a disconnect FET optionhich is controlled by the LTC7820 FAULT pin to disconnectthe load during startup as shown in the schematic.

Please refer to “Voltage Divider PrebalanceBefore Switching”section in the LTC7820 data sheet for more detailsregarding the startup of the voltage divider. The board also features some protection functions such as overcurrentand thermal shutdown to make it a reliable solution.

演示板2543A指标(TA = 25°C):


图8.演示板2543A测量建立图

图9.演示板2543A电路图(1)

图10.演示板2543A电路图(2)
演示板2543A材料清单:



图11.演示板2543A PCB设计图(顶层)

图12.演示板2543A PCB设计图(底层)
详情请见:
http://cds.linear.com/docs/en/datasheet/7820fa.pdf
http://cds.linear.com/docs/en/demo-board-manual/DC2543AF.PDF
以及http://cds.linear.com/docs/en/demo-board-schematic/DC2543A2-SCH.PDF
7820fa.pdf
DC2543A2-SCH.PDF
DC2543AF.PDF
DC2543A.zip

 

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