lpcware

LPC3250 RTC供电故障 导致LPC3250无法引导

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by fq1110 on Tue Dec 03 01:07:57 MST 2013
各位朋友,大家好,请教一个问题,
在使用LPC3250过程中遇到这么一个问题,现在我们的RTC电路由battery供电,当battery用完后,有一大部分 LPC3250就再也无法boot,无论是uart,还是spi,还是nand都不能引导。除非给RTC供电。
但是有一小部分LPC3250又能正常引导。
看手册上有这么一段
An ONSW output pin is included to assist in waking up when the chip has had power removed to all functions except the RTC and Battery RAM。
The ONSW output pin can also be triggered by a match event, and cause an external power supply to turn on all of the operating voltages, as a way to startup after power has been removed.
这个RTC如果异常,ONSW则不能唤醒芯片,导致LPC3250无法引导。
我用示波器测量ONSW pin脚,能正常启动的,与不能正常启动的LPC3250,都是低电平。
这是什么原因呢?需要如何处理呢?

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