Laird Sterling-EWB, Руководство пользователя

Страница: 7 / 18

https://www.lairdconnect.com/ 7
© Copyright 2019 Laird. All Rights Reserved
Americas : +1-800-492-2320
Europe : +44-1628-858-940
Hong Kong : +852 2923 0610
Figure 4 shows the EWB development board power supply tree.
DC Jack
(J18)
4x AA
(J8)
Bench
(J9)
microUSB
(J24)
microUSB
(J14)
D3
D4
D5
D6
SW7
POWER INPUT
SOURCE SELECT
USB
EXT
3.3V
Regulator
3.3V
Regulator
U5
U6
DEBUG
PROGRAM
OPTIONAL
USB
4.4 – 10V
4.4 – 10V
4.4 – 7.2V
SW8
EWB RADIO POWER
SOURCE SELECT
3V3_VDD 3V3_MCU 3V3_WIFI
SINGLE
SEPARATE
Figure 4: EWB development Kit power supply
There are five options for powering the development board:
▪
DEBUG/PROGRAM USB port (micro-B connector)
– If using the FTDI USB-UART path (Default)
▪
OPTIONAL USB port (micro-B connector)
– USB function is not supported/connected on the EWB module, but port can
be used as a power input
▪
External DC supply (4.4V-10V), into DC jack connector (J18)
▪
External DC bench supply (4.4V-10V) using 2-pin header (J9)
▪
AA batteries
– Four AA batteries connected to terminal block (J8)
The external power sources are fed into selection switch SW7 which allows the selection between either USB sources or the
external DC sources.
The external power source is regulated to a fixed 3.3V on the development board. Two regulators are on the development
board to provide the option to power the EWB module from a single supply or to separate the supplies for the EWB MCU
(3V3_MCU) and radio (3V3_WIFI) sections. The development board peripherals are also powered by U5 (3V3_VDD).
The EWB module power supply inputs are sourced as following on the development board:
3V3_WIFI
▪
VDD_WIFI_PA (pin 9)
▪
VDD_WIFI_IO (pin 41)
▪
VDD_WIFI (pin 62)
3V3_MCU
▪
VDD_MCU (pin 37)
▪
VDD_USB (pin 35)
▪
VBAT (pin 80)
Note: The EWB module currently does not support the external USB interface, so the VDD_USB pin is tied directly to
3V3_MCU. The VDD_USB pin supplies power to GPIO PA11 and PA12 on the EWB module.