DocID027290 Rev 1

15/34

AN4635

Power consumption comparison

33

6.1

Stop vs. Sleep mode

The first comparison deals with the difference between the Sleep and Stop modes.

While waiting for the incoming communication, the device wants to minimize the power

consumption. The black line in Figure 2 represents debug configuration with device waiting

in Sleep mode. Using the LSE clock and LPUART peripheral the Stop mode can be

employed up to speed of 9600 baud, this is the green line. Finally, with purple line we can

see the absolute minimum current absorbed in Stop mode where the debug lines are

configured as analog input and the device is using the ULP + FWU combination.

Figure 2. Stop vs. Sleep mode

Table 4. Configurations - Stop vs. Sleep mode

Curve in Figure 2

Black

Green

Purple

Idle mode between

transmissions

Sleep

Stop

JTAG interface

ON

OFF

Current average

over phases 2, 3 and 4

18.35 µA

17.66 µA

16.99 µA

Clock

500 kHz MSI

Voltage regulator

Range 3

ULP/FWU

+/+

AHB/APB ratio

1/1

Baud rate

9600

SW used

Interrupt operation (Com IT) with defines RXSLEEP and TXSLEEP