Questions are at the end
I did some measurements with nucleo stm32l053r8, stlinkv2 cut off, led3 removed
power supply form v3pwr via
- 3.3V cn6 pin4
- GND cn6 pin6
Tools used
- stm cubemonitor power v1.2.1 & stlinkv3pwr
- multimeter (should still count as factory calibrated, price roughly 2x stlinkv3pwr -> values should be OK)
Measuring current
- via IDD
- in power wire
Code Basis: cubemx stm32 project for stm32l053r8 with
- all free pins analog
- MSI clock 1MHz
- USART2 9600 Bit/s
Measurement settings : voltage 3.3V, sampling frequency 100 Hz
Full Power Code:
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_USART2_UART_Init();
/* USER CODE BEGIN 2 */
while(1) {
}
/* USER CODE END 2 */
…
stm cubemonitor power, multiple measurements
- between 370 uA and 380 uA
- sometimes more ripple, sometimes less
- several times jumps in current, see one example image
multimeter in power line
- value continuously changing, from 371 uA to 377ua with 3.3 uA to 3.7uA AC
multimeter in IDD
- value continuously changing, from 206 uA to 214uA with 6.6 uA to 6.9 uA AC
- value seems to follow the sawtooth pattern
Expected for MCU at 3.3V and 1 MHz, see “Table 28. Current consumption in Run mode, code with data processing running from Flash”
-> Should fit for 1MHz run from Flash
Standby Code:
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_USART2_UART_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);
HAL_PWR_EnterSTANDBYMode();
…
stm cubemonitor power, multiple measurements
- between 158 uA and 159 uA
multimeter in power line
- value continuously changing, from 161.9 uA to 162.1 uA with 0.1uA AC
multimeter in IDD
- value continuously changing, from 1.78 uA .. 1.80 uA with no AC
Expected; see "Table 36. Typical and maximum current consumptions in Standby mode"
No IWDG / LSI OFF TA = − 40 to 25°C 0.29 0.6 uA
IWDG / LSI ON TA = − 40 to 25°C 1.3 1.7 uA
Should be OK as not configured to use LSE
Question 1
Given Run Mode
~375uA Board incl MCU - ~210uA MCU —> ~165uA board
UART2 is configured but not in action
Given Standby Mode
~162uA Board incl MCU - ~2uA MCU —> ~160uA board
Where is the ~160uA going on the board
Question 2
A current jump as in the screenshot has happened to me quite often. Is this OK for the v3pwr ?
Schematic should guide you on where to look.
Looks like you are backpowering U4 which is surely drawing some current. Removing SB2 would solve.
Current will spike as the MCU does stuff. No need to be concerned.
