I am using NXP LPC4078, the RTC module is onchip. To maintain the RTC, I use a CR1620 battery from Panasonic.
In theory, the battery can maintain real time over than 5 years. However, some of my product just run out of battery (measured voltage 0 volt) after around 4 months. Currently, we detected 2 of 500 products that happen the problem.
The circuit design is as below:
with VBAT is connected directly to pin 19 of the LPC4078 100 pin.
I don't known that problem caused by the battery or by hardware. Are there any body met that problem? Please give me any idea to solved it.
Thanks in advance,