HYT TC-580 User manual

TC-580 Service Manual
Contents
Introduction...................................................................................................................... 1
Safety Information........................................................................................................... 1
Radio Overview................................................................................................................ 2
Software Specifications .................................................................................................. 5
Circuit Description ........................................................................................................ 13
CPU Pins ........................................................................................................................21
TC-580 Parts List 1 ........................................................................................................ 25
Adjustment Description ................................................................................................ 40
Troubleshooting Flow Chart......................................................................................... 50
Disassembly and Assembly for Repair........................................................................ 53
Exploded View ............................................................................................................... 56
TC-580 Parts List 2 ........................................................................................................ 57
Packing........................................................................................................................... 59
TC-580 PCB View........................................................................................................... 60
TC-580 Level Diagram................................................................................................... 62
TC-580 Block Diagram................................................................................................... 63
TC-580 Schematic Diagram .......................................................................................... 64
Specifications ................................................................................................................ 69

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Introduction
Manual Scope
This manual is intended for use by experienced technicians familiar with similar types of communication
equipment. It contains all service information required for the equipment and is current as of the
publication date.
Safety Information
The following safety precautions shall always be observed during operation, service and repair of this
equipment.
◇This radio shall be serviced by qualified technicians only.
◇Only use HYT supplied or approved batteries and chargers.
◇To avoid electromagnetic interference and/or compatibility conflicts, turn off your radio in any
area where posted notices instruct you to do so. Turn off your radio before boarding an aircraft.
Any use of the radio must be in accordance with airline regulations or crew instructions.
◇For vehicles with an air bag, do not place a radio in the area over an air bag or in the air bag
deployment area.
◇Turn off your radio prior to entering any area with explosive and flammable materials.
◇Do not charge or replace your battery in a location with explosive and flammable materials.
◇Turn off your radio before entering a blasting area.
◇Do not use any portable radio that has a damaged antenna. If a damaged antenna comes into
contact with your skin, a minor burn may result.
◇Do not expose the radio to direct sunlight for a long time, nor place it close to a heating source.
◇During transmission, hold the radio in a vertical position with its microphone 2.5 to 5.0
centimeters (1-2 inches) away from your lips, and keep the antenna at least 2.5 centimeters
(approximately 1 inch) away from your head. If you wear a portable radio on your body, ensure
that the antenna is at least 2.5 centimeters (approximately 1 inch) away from your body when
transmitting.

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Radio Overview
(1) Strap Hole (2) Antenna (3) PTT
(Push-to-Talk) Key
(4)SK1
(programmable)
(5)SK2 (programmable) (6) LCD Display (7) Function Keypad (8) LED Indicator
(9) TK (programmable) (10)Radio On-Off/Volume
Control Knob (11) Microphone (12) Speaker
(13) Accessory Jack
Cover (14) Numeric Keypad (15) Battery Latch (16) Accessory
Jack
(17) Belt Clip (18) Battery (19) Charging Piece
﹡Function Keypad
yOK key: to access a menu or to select an option.
yDN key: to switch channels downwards during non-menu operation or to scroll options
downwards during menu operation.
yUP key: to switch channels upwards during non-menu operation or to scroll options upwards
during menu operation.
yC key: to return to the previous menu. Long press this key to return to the main menu.

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OKkey DNkey UPkey Ckey
﹡Numeric Keypad
Used to enter information for programming the radio.
y- : Used to enter numbers or characters.
y: Used to enter decimal points or characters. Press OK first and then immediately to
lock/unlock the keypad.
y: Used to enter characters.
﹡LED Indicator
Status indications and alert tones are shown in the table below:
Operations/Functions LED Indications and Alert Tones
To enter Wired Clone mode:
Turn on the source radio with
SK1 held down for
approximately 2 seconds,
and turn on the target radio
directly.
The LED on the source radio flashes red once
upon power-on.
Status of the source radio in
Wired Clone mode
(After the target radio is
turned on and the cloning
cable is connected, press
PTT of the source radio to
begin cloning.)
The LED glows red during cloning process.
The LED flashes orange upon cloning errors.
(Press OK, and then the orange LED goes out.
Press PTT to restart cloning.)
The LED solidly glows orange once cloning is
completed.
Wired Clone
Status of the target radio in
Wired Clone mode
The LED glows green during cloning process.
The green LED goes out once cloning is
completed.

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Power On (to enter User Mode) The LED flashes green once and the power-on
alert tone sounds.
Low Battery Alert The LED flashes red, and a low-pitched tone
sounds every 10 (programmable) seconds.
Transmitting
The LED glows red during transmitting.
When TOT timer expires, the radio sounds beep
tones continuously.
A TOT pre-alert tone sounds before the TOT timer
expires.
Receiving The LED glows green during receiving.
Scanning
The LED flashes green during scanning.
Scan Start Alert (programmable by the dealer):
one beep is heard.
Scan End Alert (programmable by your dealer):
two continuous beeps are heard.
Writing/Reading The LED glows red when reading data.
The LED glows green when writing data.
When a call is transmitted (within the Auto
Reset Time) The LED solidly glows orange.
When a call is received The LED rapidly flashes orange.
When an individual call is received (within
the Auto Reset Time)
The orange LED gives indication by means of
double flash.
When a group call is received (within the
Auto Reset Time) The LED flashes orange.
Adjusting TX items The LED solidly glows red.
Adjusting RX items The LED solidly glows green.

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Software Specifications
Description of Features
1. 256 available channels
2. 32 available zones
3. High /Low power switchable
4. 5 selectable VOX sensitivity levels
5. Channel Scan
6. Bandwidth Switch
7. Home Channel
8. Time-out Timer (TOT)
9. Busy Channel Lockout (transmission prohibited in busy status)
10. 9 selectable squelch levels
11. Monitor
12. Compandor
13. Scrambler
14. Whisper
15. CTCSS/CDCSS Encode & Decode (CTCSS Tail Revert of 180/120 degrees, supporting
non-standard CTCSS/CDCSS)
16. DTMF Decode
17. Manual Frequency Input
18. Keypad Lock
19. Menu Edit
20. Channel Set Mode
21. Channel Alias Display
22. Reverse Display
23. Incoming-call Display
24. PC Programming
25. Wired Clone
26. Manual Adjust
27. Battery Strength Indicator

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28. Low Battery Alert
29. Battery Save
30. Power-on Password
31. Reset: to restore factory settings
32. Emergency Alarm
33. Software Update
Description of Modes
User Mode
It is a conventional communication mode. After the radio is turned on, it enters the User mode.
PC Programming Mode
The radio in User mode enters PC Programming mode through specific protocol based communication
with the programming software. In this mode, radio functions and adjustment parameters can be set
through the programming software (including User Version and Factory Version).
Reset Mode
You can restore the settings, which may affect normal operation, to factory defaults in this mode. The
factory default settings include radio parameters, as well as 8 channel frequencies and other
channel-related parameters.
If your radio is programmed with this function, you can enable it by pressing PTT, SK1 and SK2 for 2
seconds while powering on the radio.
Channel Set Mode
You can edit parameters on the current channel through menu operation and keypad input. Once the
Channel Set mode is entered, you can select and edit parameters like TX/RX frequency,
CTCSS/CDCSS, channel spacing, power level and so on, through the menu. Such settings are mainly
made through the menu. Some of these parameters can only be selected from the drop-down list (like
Wide/Narrow channel spacing, and High/Low power level) and some can be input through numeric
keys (like TX/RX frequency).
Press and hold down PTT and SK2 for 2 seconds while powering on the radio to enter the Channel Set
mode. See the structure illustrated below:

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After the Channel Set mode is entered, you will be required to input the channel number for further
menu operation.
Level-1 Menu
(Displayed
Content)
Level-2 Menu
(Displayed
Content)
Description for Level-2 Menu
CH n
RX Freq
RX Freq
350.00000 Displays the RX frequency. Press OK to edit.

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CH n
TX Freq
TX Freq
350.00000 Displays the TX frequency. Press OK to edit.
Option Items
CH Space Sets the spacing of the current channel.
Option Items
Power Level Sets the power level of the current channel.
Option Items
Whisper Sets the whisper feature on the current channel.
Option Items
Compandor
Sets the compandor feature on the current
channel.
CH n
Option Items
Option Items
Scrambler
Sets the scrambler feature on the current
channel.
RX CTC/CDC
CTC/CDC None
Sets not to receive CTCSS/CDCSS on the
current channel.
RX CTC/CDC
CTC
Displays the RX CTCSS on the current channel.
Press OK to edit it.
RX CTC/CDC
Normal CDC
Displays the RX CDCSS on the current channel.
Press OK to edit it.
CH n
RX CTC/CDC
RX CTC/CDC
Invert CDC
Displays the RX CDCSS on the current channel.
Press OK to edit it.
TX CTC/CDC
CTC/CDC None
Sets not to transmit CTCSS/CDCSS on the
current channel.
TX CTC/CDC
CTC
Displays the TX CTCSS on the current channel.
Press OK to edit it.
TX CTC/CDC
Normal CDC
Displays the TX CDCSS on the current channel.
Press OK to edit it.
CH n
TX CTC/CDC
TX CTC/CDC
Invert CDC
Displays the TX CDCSS on the current channel.
Press OK to edit it.
Wired Clone Mode
1. Description
Wired Clone mode is an independent mode. To access other modes, you must restart the radio.
Wired Clone mode includes Clone mode and Factory Clone mode.
1) Clone Mode:
Connect two radios using a cloning cable. Then press and hold down SK1 for 2 seconds while
powering the source radio on, and the radio enters Clone mode. The target radio can be directly
turned on to enter the mode. In this mode, data stored in EEPROM of the source radio will be cloned
to EEPROM of the target radio. The data transferred only covers channel data and common
parameters, excluding adjustment data, version and serial No. of the model.
2) Factory Clone Mode:

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Connect two radios using a clone cable. Then hold down SK1 for 2 seconds while powering the
source radio on, and the radio enters Clone mode; press the SK2 afterwards to switch to Factory
Clone mode. The target radio can be directly turned on to enter the Clone mode. The data transferred
covers all data in EEPROM other than serial No, with flag of manual adjustment switch included.
2. Process
Process of Wired Clone:
1) The LED flashes red once after the source radio enters Wired Clone mode. Press PTT to begin to
clone data to the target radio.
2) During cloning, LED of the source radio solidly glows red, and LED of the target radio solidly glows
green. When cloning ends, LED of the source radio solidly glows orange, while LED of the target
radio goes out, and the target radio restarts automatically to prepare for a further clone.
3) If any abnormal situation occurs during cloning, the source radio will stop cloning and its orange
LED will flash, indicating both radios are ready for another cloning operation.
4) When cloning ends, the source radio goes back to standby status no matter whether the cloning is
successful. Press PTT again to begin another cloning operation.
Manual Tune Mode
Press and hold down PTT and SK1 on the radio for 2 seconds while powering it on, and the radio
enters Manual Tune mode. (Note: This operation is subject to the option Manual Tune Mode in the
programming software. If this option is unchecked, the radio can not enter this mode, which helps avoid
change of parameters and degradation of radio performance caused by user’s misoperations.)
Keep this option unchecked after values are well adjusted from factory, to avoid any unexpected
change of values. And re-adjust the values upon your further requirement. These values will remain in
other modes.
See the tuning items illustrated below:

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1. To enter the Manual Tune mode
Hold down PTT and SK1 for 2 seconds while powering on the radio. Then the LCD displays
"Tuning Mode”, indicating that the Manual Tune mode has been entered. At this time, release the
keys.
2. To switch the tuning item
After the tuning mode is entered, switch the tuning item using UP or DN key. The LCD displays the
tuning item accordingly. The LED solidly glows red for the TX group items and glows green for the
RX group items.
3. To adjust the value
At a certain frequency, short press SK1 to increase the value in the step of 1; hold down the key to
increase the value continuously in steps of 1.
At a certain frequency, short press SK2 to decrease the value in the step of 1; hold down the key to
decrease the value continuously in steps of 1.
4. To save the value
After the value is set, press UP or DN to switch the frequency, or press OK to save the value.
5. To enter the selected item
Use UP or DN key to choose your desired tuning items, and press OK to enter the item.
6. To return to the previous menu
Short press Cto return to the previous menu; and long press Cto return to the first level menu.
7. Measures on special items
TX group items: Including the VOX Level 1-5 and TX Low Voltage Threshold. These tuning items
are related to AD sampling. Short press SK1 or SK2 after entering the above
items, to activate AD sampling (including calculation) once. Press UP or DN to
switch the frequency and press OK to save the current AD sampling value. If
neither of SK1 or SK2 is pressed, the tuning value will not be updated, and AD
sampling will not be activated.
Rx Group Items: Including the SQL On 1, SQL On 5, SQL On 9, SQL Off 1, SQL Off 5, SQL Off 9
and Rx Low Voltage Threshold. These tuning items are related to AD sampling.
Short press SK1 or SK2 after entering the above items, to activate AD sampling
(including calculation) once. Press UP or DN to switch the frequency and press

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OK to save the current AD sampling value. If neither of SK1 or SK2 is pressed,
the tuning value will not be updated, and AD sampling will not be activated.
8. Description of key-press
Short press: indicates to press the key for shorter than 1 second;
Long press: indicates to press the key for 1 second or more.

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Circuit Description
General Realization Method
TX Section: The audio signal from MIC is amplitude limited and amplified by U203. After that, the
signal feeds to the AGC circuit and then to the baseband processor U202 in AK2347, where the signal
is filtered, compressed, pre-emphasized and amplitude limited. The signal from AK2347 goes to VCO
for frequency modulation (the PLL system is composed of U101, Q100 and Q101). After modulated
onto the RF carrier, the signal is processed by the buffer amplifiers Q104 and Q106. Then the signal
passes through the TX/RX switch D401, and goes to the front-stage power amplifier for
pre-amplification. After that, the signal is further amplified by the driver amplifier Q402, for obtaining the
power to drive the final-stage amplifier. After the signal is amplified by the final-stage amplifier (Q403),
the signal with required power is generated. Then it passes through the TX/RX switch D403, and feeds
to the low-pass filter circuit. Finally, the signal is transmitted via the antenna after high-order harmonics
are removed (The TX/RX switch circuit is composed of D401, D511, D403, D501 and D502).）
RX Section: The RF signal from the antenna passes through the low-pass filter, and then feeds to the
bandpass filter (composed of D514, D515 and D516) to filter out undesired out-of-band interference
signal. Then the desired RF signal enters the high-frequency low-noise amplifier Q501, where it is
amplified. The amplified signal goes to the bandpass filter (composed of D509, D510 and D513) to filter
out out-of-band interference signal again. The desired RF signal is mixed with the first local oscillator
signal from VCO at Q502. The newly generated signal is processed by the crystal filter (Z1, Z2 or
XF501) to generate the first IF signal. After amplified at Q505, the first IF signal goes to the IF
modulator (U201), where it is mixed with the second local oscillator signal from X101 to generate the
second IF signal (it is filtered by CF201). Then U201 demodulates the second IF signal, and outputs
audio signal, which is divided into two flows and sent to the baseband processor U202 in AK2347. One
flow of audio signal is amplified, and then goes to the low-pass filter to filter out high-frequency audio
signal (CTCSS/CDCSS signal is kept). The CTCSS/CDCSS signal is sent to MCU (U611) for decoding.
The other flow of audio signal is filtered, de-emphasized and expanded, and then is sent to the audio
amplifier (U205), where the audio power of the signal is amplified to drive the speaker directly.
Power Supply Section: The 7.4V battery voltage goes to the LDO IC (U601), and generates 5V DC
voltage, which is divided into two flows. One flow is converted into 4.5V voltage via the dual LDO IC
(U602) (under the control of MCU, one flow (4.5T) supplies power for the TX circuit; one flow (V_SAVE)

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supplies power for VCO; under the control of 4.5T, V_SAVE is converted to 4.5R via Q604); the other
flow goes to the dual LDO IC (U603), and generates two flows of 3V voltage (3M1 and 3M2), supplying
power for MCU/LCD and PLL/U202(AK2347) respectively.
Signaling Encoding: MCU (U611) generates two flows of CTCSS/CDCSS. One flow is output via the RC
network, and is sent to VCO together with the audio signal for modulation. The other flow goes through
the RC network to modulate the PLL reference frequency oscillator. The signal amplitude of the two
flows can be adjusted separately.
Realization Methods of Basic Functional Modules
1 HF Section
1) Block Diagram of PLL Circuit:
Figure 1.1 Block Diagram of PLL and VCO
The PLL circuit generates RF carrier signal for TX and the first local oscillator signal for
RX.
PLL: The step frequency of the PLL circuit is 5.0KHz, 6.25KHz, 10.0KHz or 12.5KHz. In U101, the
21.25MHz reference oscillator signal is divided into 5.0KHz, 6.25 KHz, 10.0 KHz or 12.5 KHz
reference frequencies via a fixed counter in PLL. The signal output from the VCO (TX VCO/RX
VCO) is processed by the buffer amplifier Q104, and then enters PLL, where it is further processed
by the variable frequency-divider. Then the signal is compared with the reference frequency in the
phase detector (PD) of PLL. The signal from PD passes through a low-pass filter, and then is sent
to the varactors of VCO so as to control its output frequency.
VCO
Synthesizer
2SC5108
TX
RX
VCO
2SC5108
MB15E03
Ripple
TX
T/R BUF_AMP
MIXER
TX/RX
Restraint
LD
PLL_EN
PLL_DATA
PLL_CL
K
Loop Filte
r
TCXO
T/R
U101
VRCR
Q104
VCO_BUF
Q103
CTC/DCS
Q101
Q100
21.25M
V_T
V_R
Q106
PLL System
CTC/DCS

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VCO: There is a TX VCO and a RX VCO. In TX mode, PLL generates a control voltage via
the phase detector and the low-pass filter (LOOP FILTER) to control the varactor, making
TX VCO generate the RF carrier signal consistent with the preset frequency of MCU. The
modulation signal from U202 (AK2347) and MCU is modulated onto the RF carrier via
D108. Then the signal is processed by the buffer amplifier, and is sent to the RF power
amplifier circuit for power amplification. In RX mode, RX PLL generates a control voltage
via the phase detector and the low-pass filter (LOOP FILTER) to control the varactor,
making RX VCO generate the first local oscillator signal consistent with the preset
frequency of MCU. Then the signal is mixed with the received RF signal at Q502, and the
first IF signal is therefore generated.
Unlock Detector: If the LD pin of U101 is at low level, unlock status is valid. When this
status is detected by the microprocessor, neither transmission nor reception can be made,
and the unlock alarm sounds.
2) Block Diagram of The RF Power Amplifier Circuit:
2SC4988 RQA0002RD012SC5108 2SC5108
BUF_AMP
TX/RX
Q104
ANT
VCO_BUF
Harmonic_LPF
ANT_SW
TX/RX
DRV_AMPPRE_AMP Final_AMP
APC
APC
Q106 Q401 Q403Q402
VCO_OUT
PLL_RF_IN
1st Lo
Figure 1.2 Block Diagram of TX RF Circuit
The modulated carrier signal is processed by the front-stage amplifier Q401 and by the
driver amplifier Q402, for obtaining the power to drive the final-stage amplifier. Then the
RF signal is further amplified by the final-stage amplifier Q403, for obtaining required
power. The amplified RF signal passes through D403, and goes to the LC low-pass filter
circuit (LPF). Finally the signal is transmitted via the antenna after high-order harmonics
are removed in LPF.
The APC circuit is composed of U401, Q405 and Q404. U401 controls the bias voltage at
the gates of Q402 and Q403, so as to control the TX current and to further regulate power.

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3) Block Diagram of RX Low-noise Amplifier and The First Mixer Circuit:
AT41511
2SC5108
3SK318
Tuned Filter
Varactor
Tuned Filter
Q501
Q502
Harmonic_LPF
TU
XF501
TU
ANT
Q503
ANT_SW
IF_AMP
Crystal Filter
21.7M
MIXER
LNA
Varactor
TX/ R X
1ST LO
Figure 1.3 Block Diagram of RX RF Circuit
Desired and undesired RF signals received via the antenna feed to the band-pass filter to
filter out undesired out-of-band interference signal. Then the desired RF signal is
amplified by the high-frequency low-noise amplifier Q501. Afterwards, the amplified signal
goes through the bandpass filter again to filter out undesired out-of-band interference
signal. The desired RF signal is mixed with the first local oscillator signal from VCO at Q502.
The MCU outputs through APC/TU pin a voltage, which controls the central frequency of
the electrically tunable bandpass filter.
2. IF Processing and Audio Demodulation
Figure 1.4 Block Diagram of IF Processing
Narrow Band
2SC5108
TA31136
N-DET
Detecto
r
Z1，Z2 or XF501
Crystal Filte
r
21.7M
Q503
IF_AMP
Ceramic Filte
r
RSSI
U201
2nd LO
MIX OUT
A
F_DET

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The newly generated signal at Q501 is processed by the crystal filter (Z1, Z2 or XF501) to generate the
first IF signal (21.7MHz). After amplified by Q505, this IF signal enters the IF demodulator U201, where
it will be mixed with the second local oscillator signal to generate the second IF signal (450KHz). Then
U201 demodulates this second IF signal and outputs an audio signal which will be sent to AK2347.
3. MCU Control, Signal Processing and Audio Power Amplification
Circuit diagram of this section is shown as below:
C2
C
VOX
STM32F100
CPU
KEY PAD LCD E2PROM
APA_EN
PTT
AP C /T U
LED RED
TX/RX
W/N
SAVE
SK2
SK1
U611
RXD
4*4
TXD
DTMF_IN
CTC_IN
LED_GREEN
CTC/DCS
POWER_CTRL
Reset
VRCR
ALARM
VDD
DTMF/TTS
Xin
Xout
APC /TU
SAVE
TTS_IN
W/N
TX/RX
T/R
RSSI
N-DET
VOX_DET
BEEP
PLL_CLK
DTMF/TTS_OUT
R2
R
CTC/DCS_OUT
PLL_DATA
PLL_EN
T/R
CSTN
9.8304M
AK2347
Noise Detect
RSSI
VRCR
APA_ EN
LED_RED
LED_GREEN
TTS_DET
CTC/DCS_DET
DTMF_DET
Figure 1.5 Block Diagram of MCU Control Circuit
1) MCU Control Circuit
MCU control circuit is composed of MCU, EEPROM, keys and etc. This section has the
following functions: to initialize data of the radio and save data to EEPROM; to check the
battery voltage and signals from external keys, LD and VOX-DET, and make responses; to
transmit required data to PLL; to switch and control RX/TX status based on the input PTT
signal; to switch the squelch circuit on or off based on the input signaling decode signal
and squelch level signal; to control circuits of high/low power switch, audio power
amplification, VCO power supply, RX power supply and TX power supply; (for
programming) to communicate with PC via RXD/TXD, and transmit data to or receive data
from PC.

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2) Signal Processing Circuit
Figure 1.6 Block Diagram of Baseband Processing
a. TX Baseband Processing
The modulation signal from MIC is amplitude limited and amplified by U204. Afterwards, the signal
feeds to the AGC circuit and then to the baseband processor U202 in AK2347, where it is filtered,
compressed, pre-emphasized and amplitude limited. Then the modulated signal enters VCO for
direct frequency modulation.
b. Rx Baseband Processing
The DEMOD signal derived from IF demodulation has two flows after entering U202 in AK2347.
One flow of audio signal is amplified, and then goes to the low-pass filter to filter out high-frequency
audio signal and to reserve the CTCSS/CDCSS signal; then the reserved CTCSS/CDCSS signal is
sent to MCU (U611) for decoding. The other flow of audio signal is filtered, de-emphasized and
expanded, and then is sent to the audio power amplifier (U205).
c. Audio Power Amplification
The audio signal output from U202 in AK2347 goes through the volume control switch, and it is then
amplified by the audio power amplifier (U205) to drive the speaker directly.
Audio & Sub-Audio Processor
A
K2347
U202
U205
Q205
Speake
r
MIC
S201
U203
A
GC
NJM2904
TDA2822
A
PA_EN
NJM2904U204
MIC_AMP
VOX
VOX_AMP
DTMF/TTS
BEEP
OPTIONAL
VOX_DET CTC/DCS
CTC/DCS_DET
DTMF_DET
TTS_DET
AF_DET
MOD_VCO

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4. Power Supply Processing
Block diagram of power supply circuit is shown as below:
5V
LCD_3M1
PLL_3M2
MC U _3M1
AK2347_3M2
POWER_CTRL
VR_4.5V
VP_4.5V
VT_4.5V
U601 U603
Power Supply
U602
XC6401FF
XC6201P
XC6401FF
VCO_4.5V
7.4V
Figure 1.7 Block Diagram of Power Supply Circuit
Power Supply Section: The 7.4V battery voltage goes to the LDO U601 and generates a 5V DC voltage,
which is divided into two flows. One flow is converted into a 4.5V DC voltage via the dual LCO IC (U602)
and supplies the TX, RX and VCO circuits. The other flow goes through U603 and generates a 3V
voltage to supply the MCU, EEPROM, LCD, PLL, and U202 (AK2347) etc.
5. Keypad and LCD
Figure 1.8 Diagram of LCD and Keypad