基于LTR3741大功率20A降壓電源控制方案
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Linear 公司的LTR3741是大功率恒流恒壓20A降壓電源控制器，輸入電壓VIN從6V到36V，輸出電壓高達VIN-2V，穩壓精度1.5%,穩流精度±6%，效率高達94%，主要應用在通用工業領域，超電容充電，恒壓或恒流源。本文介紹LTR3741主要特性，方框圖，以及典型應用電路，包括10V/20A恒壓恒流降壓轉換器電路圖，20A超電容充電器電路圖，20A LED驅動器電路圖以及10A單個鋰離子電池充電器電路圖等。
LT3741-High Power, Constant Current, Constant Voltage, Step-Down Controller
The LTR3741 is a fixed frequency synchronous step-down DC/DC controller designed to accurately regulate the output current at up to 20A. The average current-mode controller will maintain inductor current regulation over a wide output voltage range of 0V to (VIN – 2V). The regulated current is set by an analog voltage on the CTRL pins and an external sense resistor. Due to its unique topology, the LT3741 is capable of sourcing and sinking current. The regulated voltage and overvoltage protection are set with a voltage divider from the output to the FB pin. Soft-Start is provided to allow a gradual increase in the regulated current during startup. The switching frequency is programmable from 200kHz to 1MHz through an external resistor on the RT pin or through the use of the SYNC pin and an external clock signal.
Additional Features include an accurate external reference voltage for use with the CTRL pins, an accurate UVLO/EN pin that allows for programmable UVLO hysteresis, and thermal shutdown.
LTR3741主要特性:
Control Pin Provides Accurate Control of Regulated Output Current
1.5% Voltage Regulation Accuracy
±6% Current Regulation Accuracy
6V to 36V Input Voltage Range
Wide Output Voltage Range Up to (VIN – 2V)
Average Current Mode Control
1μA Shutdown Current
Up to 94% Efficiency
Additional Pin for Thermal Control of Load Current
Thermally Enhanced 4mmx ?4mm QFN and 20-Pin FE Package
LTR3741應用:
General Purpose Industrial
Super-Cap Charging
Applications Needing Extreme Short-Circuit Protection and/or Accurate Output Current Limit
Constant Current or Constant Voltage Source
圖1。LTR3741方框圖
圖2。LTR3741 10V/20A恒壓恒流降壓轉換器電路圖
圖3。LTR3741 5V穩壓輸出的20A超電容充電器電路圖
圖4。LTR3741 20A LED驅動器電路圖
圖5。LTR3741 10A單個鋰離子電池充電器電路圖
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