DocID027351 Rev 3
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UM1855
Hardware layout and configuration
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Calibration procedure and current measurement compensation steps:
•
On JP11, short terminals 1,2 and open terminals 3,4. The current through the shunt
resistor is now zero.
•
Run low-power-mode IDD measurement as described in
Section 2.30.2
. The value
V
offset
measured corresponds to offset of the differential amplifier.
•
On JP11, add a second jumper, to short terminals 3 and 4, then remove the jumper
from terminals 1,2 of JP11. The MCU supply has not been interrupted and the supply
current now passes through the shunt resistor.
•
Run low-power-mode IDD measurement as described in
Section 2.30.2
. The value
V
measured
obtained corresponds to the sum of MCU supply current and the differential
amplifier’s offset V
offset
.
•
The software computes a V
out
number representing the MCU supply current as
V
out
= V
measured
- V
offset
Table 31. JP11 jumper settings during IDD measurement with calibration
Jumper
Setting
Description
JP11
JP11
Configuration used to measure V
offset
.
JP11 in VDD position
STM32L476ZGT6 supply current does not flow through shunt
resistor.
JP11
Configuration to transit from direct to shunted supply to
STM32L476ZGT6, without ever interrupting the MCU supply.
JP11
Default setting.
Configuration used to measure the MCU supply current.
JP11 in IDD position
STM32L476ZGT6 supply current flows through shunt resistor.
İ
1 2 3 4
İ
1 2 3 4
İ
1 2 3 4
