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[原创] ST PM8804以太网加电PD转换器4V 8A解决方案

关键词:电源管理 以太网加电 PoE PWM IEEE802.3.af/at/bt

时间:2019-05-16 11:24:24       来源:中电网

ST公司的PM8804以太网加电PD转换器是PWM控制器(峰值电流模式),集成了设计用于PoE和电信中等功率智能和有效48V应用所有需要的电路.PD转换器具有5V 8A输出,具有同步反激,与IEEE802.3bt标准兼容.PM8804具有可编程振荡器,用于开关频率,可调斜率补偿,双互补的具有可编死区时间,可编软起动,软关断和可编电流检测消隐时间(高达200ns)的低边驱动器.其内部高压线性稳压器具有典型20mA输出电流,使得器件能以最少化外接元件来起动.输入工作电压高达75V,栅极驱动器1A峰值电流,最大占空比80%,CTL引脚上的内部上拉电阻可连接光耦合器,工作电流消耗小于1.5mA,主要用于PoE加电设备如IP电话,WLAN接入点和网络照相机以及电信电源.本文介绍了PM8804主要特性,内部框图,应用电路图和以太网加电评估板STEVAL-POE002V1主要特性,电路图和材料清单.

The PM8804 is a PWM controller that integrates all the circuitry required to design a smart and efficient 48 V converter for PoE and telecom mid-power applications.

It features a programmable oscillator for the switching frequency, adjustable slopecompensation, dual complementary low-side drivers with programmable dead time,programmable soft-start, soft turn off and a programmable current sense blanking time.

An internal high-voltage linear regulator with a typical 20 mA output current allows the device to start up with a minimum of external components.Complementary 1 A peak gate drivers make possible to implement high power topologies,while when the second drives is not used, like with simple low power flyback converters, it can be turned off.

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