Hardware and layout UM1018
16/44 Doc ID 18141 Rev 1
2.16 IDD measurement
The built-in IDD measurement circuit implemented allows the consumption measurement of
the STM32L152C6T6 while the MCU is in Run or Low power saving modes.
For IDD measurement the circuit below is implemented on STM32L152-EVAL.
Figure 4. STM32L152-EVAL IDD measurement circuit
2.16.1 Run mode
In Run mode, IDD current is measured using the operational amplifier MAX9938FEUK+
(U10) connected to the 1 Ohm shunt resistor (R36).
In this case IDD_CNT_EN remains high during measurement, so R35 remains in short-
circuit during the measurement because of transistor T4 which remains ON permanently.
Jumper JP4 must be connected between pins 2 and 3.
2.16.2 Low power mode
In Low power modes (Stop or Standby), the operational amplifier MAX9938FEUK+ (U10) is
connected to the 1 KOhm shunt resistor (R35), controlled by the analogue switch T4.
In this case the counter 74HC4060 (U6) enabled by IDD_CNT_EN manages the
measurement timing according to Figure 5.
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