nRF51822 showing short in power after it is first powered on a custom board

[deepu]

hello,

We have developed a custom board corresponding to mbed pca10024 evaluation board.We haven't mounted the rf section and not even the crystal.The only thing that the board contains as hardware is nrf51822 IC,capacitors at AVDD,VDD.Then we tried programming the board using JLink-edu in keil and programmed it with "blinky example" provided by nordic.The programming was successful with led connected at a gpio pin started to blink for few seconds,and suddenly it stopped .When we checked the board it shows short in power.This happens for every board for which board detection and programming is successful for the very first time it is tried and then shows short in vcc and gnd

please help us sort out this issue

[RK]

Don't see really how anyone can help you with a short on your own custom board, it sounds like you have a fault on your board which is causing it. How are you even detecting that there is a short? Did it smoke, or make a pop noise, the kind of sound which might indicate a capacitor shorted out and connected VCC and ground?

[deepu]

nothing like that,used a multimeter

[RK]

You measured the voltage between VCC and GND and found it to be zero or you used a multimeter in 'short detect' mode, in which case you just put a random voltage across the chip and the rest of the circuit? A multimeter isn't a very good way to test complicated assemblies.

Did you test a board with your multimeter before and after? If there was no short beforehand and there's one afterwards, then one of the components on your board shorted out.

[Locky]

I'd start by removing capacitors one at a time and test. It sounds like you may have an under-spec capacitor that has failed as a short. Sometimes X5R and X7R caps can fail as a short.

What voltage Vcc are you supplying the board for programming? testing?

Do you have any GPIO's which are connect to Vcc through a resistor?

[RK]

short capacitor was my first thought too, my expectation was any GPIO connected to VCC or GND would be sufficiently current-limited not to be a problem so I could only think some component on the board between VCC and GND had shorted directly.