Marco Di Biaggio

LPC54618 and RTC Battery power consumption

Discussion created by Marco Di Biaggio on May 3, 2020
Latest reply on May 21, 2020 by xiangjun.rong

Good morning,

I have a problem with power consumption of LPC54618 RTC. As illustrated in attached PDF I have a board with the configuration visible on the schematic. Battery is a rechargeable Panasonic VL-1220 with 7mA/h current capacitance. LPC54618 datasheet reports that, in power off conditions (board off, with only VBAT present), consumption is 340nA. I can't measure precisely the consumption, but after several tests, I see that the current absorbed from RTC is more than that indicated. I tried to left reset pin floating ad suggested in the datasheet, but without significative differences (and how can I left floating a reset pin?!?!). I have 2 different boards with same LPC54618 RTC circuit and same problem.

Is there anyone that can help me to understand how solve this problem?

For information I used same battery on LPC1768 controller (that has similar consumption characteristics) without problems and duration about 6 months.

Many thanks in advance for any information.

Best regards,

Marco Di Biaggio