Hello NXP,
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,
Hi,
Please check if you can find any different impedance between a good board and a failed board.
Please measure the current on failed boards and good boards.
If you change the battery on a failed board, does the problem persist?
I want to isolate the problem and verify that it is not the battery issue.
Have a great day,
Soledad
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Hello Soledad,
Thank you for your reply,
The good board and the failed board are same current, around 1.1 uA. After we detect a failed board, we just change the battery and keep monitoring. but after 5 months ago, the voltage of the battery still hold good.
From that information, may I think that the battery was not charged full? The battery is from Panasonic, a huge company. So that the defect product seem to bee very rare. Our defect rate is 2 pieces per totally 500 pieces.
From your experience, do you think that the battery is not charged full?
Best regards,