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2.2.6.2
Reset Circuit
The MCU (IC7) has an integrated power-on reset (POR) / power-down reset (PDR) circuitry. However, the power-down reset (PDR)
does not choose at this model.
When the power is turned off, Reset IC (IC1) as 3.1V reference voltage detects that the Battery voltage fall, and then Reset IC (IC1)
outputs a low level signal to the MCU (IC7).
2.2.7 Power Supply Circuit
2.2.7.1
Power Switching Circuit
There are five 3.0V power supplies as [3M], [3MS], [3MA], [3T] and [3R].
[3M], [3MS] and [3MA] are always ON. [3T] is output while TX mode and is the 3.0V for transmitter circuit. [3R] is the 3.0V for receiver
circuit. [3R] is output while RX mode but it's not output when the save function is active.
2.2.7.2
Voltage Reference
[Vref] is reference voltage for audio signals. The reference voltage is approx. 1.5V.
2.2.7.3
[8V] Circuit
[8V] is generated by 6 times voltage rectification circuit (D36, D37 and D38) with the MCU (IC7) clock 200 kHz.
2.2.7.4
Battery Saver
If no activity is detected (squelch closed) on the channel, the units enters into the battery save mode controlled by the MCU (IC7). In
this mode, [3RC] lines are set low, causing IC23 to disable [3R].
2.2.7.5
LCD Driver Circuit
The Segment LCD is driven by the LCD driver (IC25).
The duty is 1/4, and the bias is 1/3.
1-10 (No.RA066<Rev.001>)
BATT
F3
IC3
2.5A
IC1
IC28
IC2
/BINT
3MSC
IC23
3RC
IC7
MCU
IC24
3TC
200kHz
D36
Fig.13 Power supply circuit
LCD DRIVER
COM1~COM3
LCD
SEG0~SEG15
Fig.14 LCD circuit
3M
3MA
3MS
IC15
Vref
3R
3T
D37
D38
8V
IC25
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