The nRF51822 is halted or hand_up frequently。Why？

[??]

Hello,this is Lee.I have a problem about nRF51822. When I turn on/off the power 2.8V to it ,it hangs up frequently.I check POR function,I found that the residual voltage (VDD) decreases slowly and stop at 0.5V.I doubt that
the residual voltage (VDD=0.5) cause nRF51822 not to be reseted and hangup.

when the VDD powers on angain,POR doesn't function and nRF51822 isn't running.

I don't know why? 1,the residual voltage(VDD=0.5)? 2,the power's noise? What is the casue of the nRF51822's halted (or hang_up)?

my contact:[email protected] Eng.Lee

[??]

Yes，it is so。CSCS7546-V3.pdfMCP1640T-I.pdf I turn off U1 （MCP1640T , DCUP charger),but the VDD drops to 0.5V .（There are some leak current in our board。） then I turn on U1 again,the VDD return to 2.8V，but the nRF51822 can't resume running。

I have some analysises： 1，Does the residual voltage (VDD=0.5) cause that the NRF51822 isn't be resetted completely? 2, Does the MCP1640T 's switching noise casue that the NRF51822 hangs up?

What is your idea？

QWE Lee