HYT TC-618, Service Manual

Page: 17 / 110

TC-618/626 Service Manual
16
6. MCU Control Circuit
The block diagram of the MCU control circuit is shown in the figure below. MCU operates on the clock
frequency of 7.3728MHz.
/LIGHTING
X601
MB95F108AK
WPFV-GE1
AT24C64
APC/TUNE
U605
U610
Reset
IC
U609
MON2
BAT
7.3728M cry stal oscillator
PTT2
PLL
1.VOX
2.BUSY_DET
3.BEEF/CALL
4.T/R
5.SAVE
6.DC/CTC
7.W/N
8.UART
9.BAT_BAT
10.PLL_LD
CHANNEL SW
Figure 8
The MCU control circuit is mainly composed of MCU, EEPROM, reset IC, keys, knobs, etc. Main
functions realized by this circuit are:
1) Signal Control:
To control Battery Save Mode;
To control high/low power switch;
To control wide/narrow bandwidth switch;
To control Tx/Rx switch;
To control APC/TUNE output voltage;
To control Tx power supply and power supply of audio amplifier;
To control SQL OFF detection.
2) Signal Detect:
To detect startup of external PTT, MONI and VOX;
To detect unlocking of PLL;