Linear公司的LTC3803-5是工作在–55℃ 到150℃的固定頻率恒流模式的反激電源控制器,最適合用來(lái)驅(qū)動(dòng)高輸入電壓的N-MOSFET.工作電壓可低至5V,輸出電壓精度可達(dá)±1.5%,靜態(tài)電 流僅為240uA,主要用在42V和12V汽車電源,通信電源,以太網(wǎng)供電(POE),輔助電源等.本文介紹了LTC3803-5主要特性, 方框圖和多種應(yīng)用電路.

The LTC3803-5 is a constant frequency current mode flyback controller optimized for driving N-channel MOSFETs in high input voltage applications. The LTC3803-5 operates from inputs as low as 5V. Constant frequency operation is maintained down to very light loads, resulting in less low frequency noise generation over a wide range of load currents. Slope compensation can be programmed with an external resistor.

The LTC3803-5 provides ±1.5% output voltage accuracy and consumes only 240μA of quiescent current. Groundreferenced current sensing allows LTC3803-5-based converters to accept input supplies beyond the LTC3803-5’s absolute maximum VCC. For simplicity, the LTC3803-5 can be powered from a high VIN through a resistor, due to its internal shunt regulator. An internal undervoltage lockout shuts down the IC when the input voltage is too low to provide suffi cient gate drive to the external MOSFET.

The LTC3803-5 is available in a low profi le (1mm) 6-lead SOT-23 (ThinSOT?) package.

LTC3803-5主要特性:

VIN and VOUT Limited Only by External Components

4.8V Undervoltage Lockout Threshold

Operating Junction Temperature from –55℃ to 150℃

Adjustable Slope Compensation

Internal Soft-Start

Constant Frequency 200kHz Operation

±1.5% Reference Accuracy

Current Mode Operation for Excellent Line and Load Transient Response

No Minimum Load Requirement

Low Quiescent Current: 240μA

Low Profi le (1mm) SOT-23 Package

LTC3803-5應(yīng)用:

42V and 12V Automotive Power Supplies

Telecom Power Supplies

Auxiliary/Housekeeping Power Supplies

Power Over Ethernet

圖1.LTC3803-5方框圖

圖2.LTC3803-5雙輸出轉(zhuǎn)換器應(yīng)用電路圖

圖3.LTC3803-5 2W絕緣輸出轉(zhuǎn)換器應(yīng)用電路圖

圖4.LTC3803-5 3.3V雙輸出反激DC/DC轉(zhuǎn)換器應(yīng)用電路圖