基于LTC3803-5设计的高温150度C反激电源控制技术

LTC3803-5是Linear公司的工作在–55℃ 到150℃的固定频率恒流模式的反激电源控制器,最适合用来驱动高输入电压的N-MOSFET.工作电压可低至5V,输出电压精度可达±1.5%,静态电流仅为240uA,主要用在42V和12V汽车电源,通信电源,以太网供电(POE),辅助电源等.本文介绍了LTC3803-5主要特性, 方框图和多种应用电路.

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应用:

42V and 12V Automotive Power Supplies

Telecom Power Supplies

Auxiliary/Housekeeping Power Supplies

Power Over Ethernet

图1.LTC3803-5方框图

图2.LTC3803-5双输出转换器应用电路图

图3.LTC3803-5 2W绝缘输出转换器应用电路图

图4.LTC3803-5 3.3V双输出反激DC/DC转换器应用电路图