路过的进来看看、、、器件的选择问题

请铭记

Hi：U13就是相当于一个Nmos开关的作用，不明白为什么不直接用NMOS器件，成本不是吧？还是说USB电源这块有什么特殊的要求吗？小弟不太明白，求粮、、、、thanks！

Vincent.M

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USB供电电路这用过两种：MOSFET做USB供电开关用；用专用的可设置限流值的开关芯片，如SIP4610。
RT9701看起来这里用来实现两个目的：
1、A built-in charge pump is used to drive the N-Channel MOSFET that is free of parasitic body diode to eliminate any reversed current flow across the switch when it is powered off——区别于mosfet，无寄生的并联二极管，防止反向电流
2、The current limit threshold is set internally to allow a minimum of 1.1A through the MOSFET but limits the output current to approximately 1.5A typical——固定值1.5A限流

lxizj

不一样哦，用MOS FET做的，算是负载开关。而RT9701是限流开关。

kaka198510

限流的作用,USB一般会限制在500ma和900ma

超級狗

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kaka198510 发表于 2013-7-11 09:59
. c% ?9 L' C5 k  Z9 @  U' Q7 E限流的作用,USB一般会限制在500ma和900ma

Richtek RT9701
Several protection functions include soft start to limit inrush current during plug-in, current limiting at 1.5A to meet USB power requirement, and thermal shutdown to protect damage under over current conditions.

可以不放，就看你在不在意這些問題，還有認證過不過得了。

{:soso_e144:}

请铭记

超級狗 发表于 2013-7-11 11:24
Richtek RT9701
Several protection functions include soft start to limit inrush current during plu ...

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THANKS