Acconeer XE123, Руководство пользователя

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Entry+ module EVK hardware user guide
Page 11 of 28
2022-07-06
© 2022 by Acconeer – All rights reserved
3.1.2. Power
In the text below, the reference designators refer to the Electrical Schematic of XE123/XE124 in
chapter 3.1.4.
The XE123/124 is powered via the USB connector J1 and/or via the pin header J5. The USB 5V
power domain supplies the USB-UART chip (U2). If the USB-UART interface is not used, a
dedicated USB charger can be used.
The XM123/XM124 module mounted on the XE123/124 can be powered either from a 1.8V LDO
(U5) which is supplied from the USB 5V power domain or from “V_EXT” in the J5 pin header.
V_EXT should be 1.8V.
The power source for XM123/XM124 is determined by the setting of the switch “SW3”. When the
LED D4 on the XE123/124 is lit, the XM123/XM124 is powered
It should be noted that regardless of if “V_EXT” or “1.8V” is used to power XM123/XM124, the LED
D4 will consume power since it is connected to “V_MISC”. If one wants to measure only the current
consumed by XM123/XM124, power should be supplied to XE123/124 via the pin “VIN” (pin 4 in
pin header J5). In this case, the solder-bridge “SB12” should be cut. This way, all components on
XE123/XE124 are supplied from the 1.8V LDO, but XM123/XM124 is supplied from the external
power supply. D4 will not indicate if XM123/XM124 is powered after SB12 has been cut.
The intention of the power pin header J5 is that it can be used both for supplying power to
XM123/XM124 and for measuring current over a measurement resistor. SB12 is a short-circuited
solder-bridge, but the customer can change it to a low-value measurement resistor with high accuracy
to perform very accurate measurements of the XM123/XM124 current. See Table 2 for the pin
assignment of pin header J5.
To minimize the current consumption of the XM123/XM124 module, the voltage to “1V8”
(VIN_VIO) can be turned off when the A111 radar sensor is disabled (ENABLE=0). To do this, the
power switch U7 must be controlled by a GPIO of your choice from XM123/XM124. If a GPIO on
pin header J2 is connected to the signal “PS_EN” (PIN 2 on J2), and solder bridge “SB11” is cut, the
power switch ON/OFF state is controlled by this GPIO. The SW to do this is not provided by
Acconeer and must be implemented by the customer. By default, the power switch U7 is always on.
3.1.3. Not Mounted Components
As can be seen in the schematic in chapter 3.1.4, USB connector J4 and several other components are
“No Mount”. These components are related to the FTDI I2C-USB bridge chip FT4222H which can be
mounted on the PCB. It was added for internal Acconeer use, but customers are of course free to
mount these components if they wish. The I2C interface is also accessible in pin header J2. Refer to
Table 4.