STMicroelectronics 32L4R9IDISCOVERY, Руководство пользователя

Страница: 22 / 78

Hardware layout and configuration UM2271
22/78 DocID030906 Rev 2
The ST890 power switch protects the host USB port against current demand exceeding
625 mA, in case a short circuit occurs on the board (the red LED fault LD5 lights on).
32L4R9IDISCOVERY can also be supplied by STLINK USB power source with no
enumeration, such as a USB charger. In this particular case, the SB36 solder bridge must
be closed. ST-LINK/V2-1 turns the ST890 power switch On regardless of enumeration
procedure result and passes the power unconditionally to the board. The green LED LD8
lights on whenever the whole board is powered.
10.6.4 Measurement of MCU current consumption
Jumper JP1 allows the consumption of STM32L4R9AI to be measured directly by a built-in
MCU current ammeter circuit (MFX_V3, able to measure from 60 nA to 50 mA) or by
removing the jumper and replace it by an external ammeter (see
Table 8 ).
To measure the MCU consumption in standby or shutdown modes, MFX_V3 needs to run
software. To wake up MCU from these modes, it is necessary to press the Reset button B1,
or to wait a few seconds.
VDDA and VDDUSB power inputs from STM32L4R9AI can be connected to two different
power sources, +3V3 or VDD_MCU. These power inputs may be included or not in the IDD
current measurement of VDD_MCU, depending on the JP3 jumper configurations described
in
Table 9 .
Table 8. JP1: IDD_MCU measurement setting
Jumper Setting Description
JP1
Default setting.
A module on the board is designed to measure from 60 nA to
50 mA by using several MOSFET, and switching automatically
depending on the read value.
STM32L4R9AI is powered by VDD. MCU current measurement
is not possible
No jumper on JP1: an ammeter can be connected on
pins 2 and 3 to measure STM32L4R9AI current (if there is no
ammeter, STM32L4R9AI is not powered).
Table 9. JP3: VDDA and VDDUSB, settings
Jumper Setting Description
JP3
Default setting.
VDDA and VDDUSB power pins of STM32L4R9AI are supplied
with +3V3. the IDD measurement does not include their current
consumption. USB OTG FS is functional even if JP7 is set on
+1V8.
VDDA and VDDUSB power pins of STM32L4R9AI are supplied
with VDD_MCU. The IDD measurement includes their current
consumption.