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High power consumption in StandBy mode

Question asked by Tuomas on Mar 21, 2012
Latest reply on Mar 24, 2012 by Clive One
Hi

I have my F205 (and F405) going to StandBy mode and waking up properly. I have confirmed that from the PWR_CSR register's SBF flag and also the 25MHz HSE is turned off properly according to an oscilloscope (I don't have LSE).

But I'm getting quite high power consumption and I have no idea why. Here's a blog post with an image of the board to get some idea about the stuff in it:

http://snowcap.fi/blog/2012/01/24/control-board-pcbs-arrived/

The board takes around 24mA when running (power led on and an user led blinking). In StandBy mode it takes about 5.5mA with the power led on. According to my measurements and tests the leds take a bit over 1mA each. This is measured by bypassing the 3.3V regulator and providing 3.3V directly.

Here's the code I'm using to go to the StandBy mode:
1.SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
2.PWR->CR |= (PWR_CR_PDDS | PWR_CR_LPDS | PWR_CR_CSBF | PWR_CR_CWUF);
3.RTC->ISR &= ~(RTC_ISR_ALRBF | RTC_ISR_ALRAF | RTC_ISR_WUTF | RTC_ISR_TAMP1F | RTC_ISR_TSOVF | RTC_ISR_TSF);
4. 
5.sc_led_on();
6.__WFI();

Any suggestions about lowering the power consumptions?

Thanks.

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