STMicroelectronics B-G474E-DPOW1, Руководство пользователя

Страница: 26 / 54

Table 8. PD2 and PC12 function
Command
Logic
state
(1)
Description
USBPD_550mA_PROTECT (PD2)
0 Deactivated
1 Connects R99 in parallel to R101
5V_USBPD_PROTECT_1A (PC12)
0 Deactivated
1 Connects R102 in parallel to R101
1. The default setting is in bold.
It is possible to increase the default current limitation set on the 5V_USBPD supply following the next table
settings.
Table 9. Typical current protection on 5V_USBPD
Mode 5V_USBPD_PROTECT_1A (PC12) (1) USBPD_550mA_PROTECT (PD2) (1) 5V_USBPD typical protection
Default 0 0 380 mA
Mode 1 0 1 520 mA
Mode 2 1 0 810 mA
Mode 3 1 1 950 mA
1. The default setting is in bold.
Note that the current protection set on 5V_USBPD may include the current drawn by the 3V3_STLK power supply
at the start. This additional current depends on the 5V_USBPD, the 5V_USB_CHGR, and the 5V_VIN voltages of
the board. It can reach 150 mA maximum and can be suppressed by removing SB31. Note also that removing
SB31 may bring a behavior constraint: upon USB STLK insertion, the board is reset unless JP7 is removed.
In case of overcurrent detected on 5V_USBPD, the LTC-3114-1 progressively lowers 5V_USBPD voltage and
may reset the Discovery board. The LEDs LD7 and LD6 may indicate such a 5 V power decrease. By shutting
down the 5V_USBPD voltage, the current on USB Type-C
®
V
BUS
of CN2 decreases, protecting the USB Host
from overcurrent.
The current protection set on 5V_USBPD supply leads to corresponding current protection on USBPD_VBUS of
USB Type-C
®
CN2 connector. Table 10 gives typical figures for two use cases.
Table 10. Typical current protection on CN2
Mode 5 V USBPD_ VBUS nominal voltage (1) 15 V USBPD_VBUS nominal voltage
Default 0.45 A 0.15 A
Mode 1 0.7 A 0.23 A
Mode 2 1.2 A 0.4 A
Mode 3 1.5 A 0.45 A
1. The default setting is in bold.
An USBPD_Detach function is designed to be able to monitor the USBPD_VBUS voltage on an
STM32G474RET6 microcontroller ADC. It is used by the USB software stack to get a USBPD_VBUS voltage
status close to the USB Type-C
®
connector and manage the unplugging procedure.
13.1.2 Power input to the digital power buck
‑
boost feature
The USB Type-C
®
CN2 connector can also be used as a power input to demonstrate the digital power
buck
‑
boost converter feature of the B-G474E-DPOW1 product (Refer to Section 13.2 Digital power buck-
boost converter ):
UM2577
USB Type-C®
UM2577 - Rev 2
page 26/54