LPC MicrocontrollersのトピックHuge power consumption on RTC ofLPCXpresso54S018M EVB.

Huge power consumption on RTC ofLPCXpresso54S018M EVB.

jcxz — Thu, 24 Sep 2026 07:44:48 GMT

I use are LPCXpresso54S018M EVB. I need the RTC in the LPC54018 to work after the main power supply is removed. I initialized and enabled the RTC in my firmware. I powered the VBATT line (J10:11) with a coin cell battery CR2032. While the main power is present, the VBATT line consumption is == 0. It's Ok. However, after removing the main power supply, the VBATT line consumption increases up to ~41 uA! According to the datasheet, consumption should be less than 1 uA. Why? How can I achieve current consumption of 1 µA or less?

Re: Huge power consumption on RTC ofLPCXpresso54S018M EVB.

Harry_Zhang — Mon, 28 Sep 2026 09:24:03 GMT

Hi @jcxz

The ~41 µA is most likely leakage through the RESETN circuitry , not RTC consumption. When main power is removed, VBAT > VDD; If VBAT> VDD, the external reset pin must be floating to prevent high VBAT leakage.

The LPCXpresso54S018M-EVK connects RESETN to its pushbutton/debug circuitry, so the unmodified EVK does not satisfy that measurement condition.

To reduce the current:

Isolate the MCU’s RESETN pin from the EVK reset network.

Harry