2-16
The power board can be divided into two parts: AC-DC, DC-DC. AC-DC part transforms the
network source into 15.2V direct voltage. DC-DC part transforms the 15.2V direct voltage
outputted by AC-DC part or lithium battery supply into several direct voltages needed by the
system: 12V, 5.0V and 3.3V. In addition, power board also realizes functions including
power-on/off control, AC indicator light, heating module drive, backlight switch control, and
lithium battery charging management, etc.
When powering on the system, power board CPU detectes the power-on signal, and control the
powering up of 3.3V, 5V, and 12V orderedly. When powering off the system, power down 12V, 5V,
and 3.3V orderedly.
Signal flow when powering on:
Power Board
Power
switch
009-004712-00
Abutting
joint
009-001776-00
Mother
Board
J2-11 12
J10-
11
12
CPU
J3-11
12
Defi
nition of power board J3
Pin No. Signal name Description
1)
RXD
received through the communication of power board
series port
2)
TXD
send through the communication of power board series
port
3)
GND ground
4)
LCD-EN LCD backlight enable signal
5)
LCD-BR LCD backlight brightness control voltage
6)
3.3VBF only used for the 3.3V when powering on/off
7)
GND ground
8)
NTC2 Lithium battery 2, connecting to thermistor signal inside
9)
GND ground
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