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STMicroelectronics Evaluation board for STM32L1 series - with STM32L152ZD MCU STM32L152D-EVAL STM32L152D-EVAL Data Sheet

Product codes
STM32L152D-EVAL
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Page of 42
UM01018
Hardware and layout
Doc ID 18141 Rev 2
17/42
2.16.3 Ibias 
current 
measurement procedure
In Low power mode the bias current of operational amplifier input (U10 pin 4) is not 
negligible compared to IDD current (typical Ibias is ~240 nA). To obtain a reliable MCU IDD 
measurement it is possible to subtract the bias current from the IDD low power 
measurement since this current is not sinked by the MCU. 
The procedure for accurate IDD measurement is:
1.
Set jumper on JP4 pins 1 and 2.
2. 
Follow the Low power mode procedure to measure I1 = I bias.
3. 
Remove jumper on JP4 pins 1 and 2 and place it on JP4 pins 2 and 3.
4. 
Follow the low power mode procedure to measure I2 = IDD + I bias.
5. 
Calculate actual IDD: IDD = I2 - I1.
         
Note:
When jumper JP4 is removed the current consumption of the STM32L can be measured by 
connecting an ammeter between jumper JP4 pin 1 and pin 2.
Note:
RDS (on) typical value of analog switch T4 = 50 micro Ohm, so to improve measurement 
accuracy it is recommended to take into account the RDS in series with R36 (1 Ohm) in the 
Idd Run mode current calculation. 
Table 12.
IDD measurement related jumpers
Jumper
Description
Setting
JP14
PA5 is connected to IDD_measurement, the output of IDD measurement circuit 
when JP14 is closed (default).
PA5 is disconnected from IDD_measurement but remains connected to BNC 
connector CN13 when JP14 is open.
JP4
STM32L is powered through IDD measurement circuit (default)
STM32L is powered directly by +3V3, IDD measurement circuit is bypassed. 
Please refer to 
 for details.
3
2
1
3
2
1