Current consumption is high in Standby ( 500uA to 1ma)

[Pkuma.21]

Hi,

I have been working in Lower devices ( STM32L0),

Using 1MHZ Clock. ( MSI)

I m using Standy Mode to reduce current consumption when i am not using controller. In Standby mode with accelerometer i am expecting 37uA current but sometimes it is consuming 500 uA to 1 ma.

I Suspect 3 things,

1) capacitors , started to reduce the capacitors in VCC line( removed C5,C6,C7,C8,C9,C10,C33 ,C34 ) and kept C19 as 4.7ua and C32 as 0.1ua near vddio2 pin after that in some devices the problem solved but after some days if i measure the same devices , the problem exits. (Capacitor details i have attached in circuit diagram)

2) In some devices in standby LED is glowing (Mildly), So i thought some clock is ON in Standby So i Started disabling all clocks while going to standby and when i disabled APB2 Clock current consumption Reduces by 150uA.

3) When i have go through some websites , there preferred to give different power suppy to VDD and VDDA pin. So , i pulled the VDDA pin off and gave 2.9v separately and found current consumption is reduced in some devices.

I have attached my standby Code:

__HAL_RCC_PWR_CLK_ENABLE();

ACCLR_StandbyMode();

__HAL_RCC_APB2_FORCE_RESET();  // added to control power in Standby

 RCC->APB1RSTR = 0xEFFFFFFFU; // PWR_EN , all periperal disabled

 SET_BIT(PWR->CR, PWR_CSR_SBF); // Standby clear

SET_BIT(PWR->CR, PWR_CSR_WUF_Pos); //Wakeup clear

 CLEAR_BIT(PWR->CR, PWR_CSR_PVDO_Pos); // PVD Clear  

RTC_AlarmDisable(RTC_ALARM_A);

RTC_AlarmDisable(RTC_ALARM_B);

RTC_TamperDisable(RTC_TAMPER_1);

RTC_TamperDisable(RTC_TAMPER_2);

RTC_WakeupTimerDisable();

/* Clear PWR wake up Flag */

__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);

/* Clear Alarm A flag */

__HAL_RTC_ALARM_CLEAR_FLAG(&hrtc, RTC_FLAG_ALRAF);

/* Clear Alarm B flag */

__HAL_RTC_ALARM_CLEAR_FLAG(&hrtc, RTC_FLAG_ALRBF);

/* Clear RTC Tamper 1 Flag */

__HAL_RTC_TAMPER_CLEAR_FLAG(&hrtc,RTC_FLAG_TAMP1F);

/* Clear RTC Tamper 2 Flag */

__HAL_RTC_TAMPER_CLEAR_FLAG(&hrtc,RTC_FLAG_TAMP2F);

/* Clear RTC Wake Up timer Flag */

__HAL_RTC_WAKEUPTIMER_CLEAR_FLAG(&hrtc, RTC_FLAG_WUTF);

/* Enable Ultra low power mode */

 HAL_PWREx_EnableUltraLowPower();

/* Enter the Standby mode */

HAL_PWR_EnterSTANDBYMode();

 

[gregstm]

All I can suggest is that try a bare board with just the micro and minimum required passive components. Capacitors are usually not a problem unless they are leaking (I had trouble with one capacitor with a lowish voltage rating - I now try to have a voltage rating as high as possible for reliability), but leave them off your "bare" test board maybe. I would be more concerned about the state of your pins when you enter standby, whether they are floating, analog, output-low etc. (the Led glowing could be a sign that the pin is floating instead of being set output-low) If you get the current you expect with the bare board, I would try touching the pins to see how stable the current consumption is (probably not a recommended method - but something I do to check for floating pins, maybe someone else will have a more professional method)

[Pkuma.21]

HI greg, thanks for ur reply. Tried tat also current consumption is same. I removed all components and try measuring the voltage of the GPIO in standby , voltage ranges from 0.1 to 0.8v (Measured all pins).

Is there a way to Pull Gpio pin Low in Standby ?

or to have a backup memory of the GPIO pins in standby ?

[Uwe Bonnes]

Did you consider the PA1 divider? The additional sensor?

[Pkuma.21]

Hi Bonnes, that pin is for ADC , i removed that pin also when measuring .

[Piranha]

Also do this before going into low-power mode:

DBGMCU->CR = 0; // Disable debug and trace in low-power modes