LG LDC-A310 CIRCUIT DESCRIPTION

Page 1
1-3. CP1 STROBE CIRCUIT DESCRIPTION
1. Charging Circuit
When UNREG power is supplied to the charge circuit and the CHG signal from microprocessor becomes High (3.3 V), the charging circuit starts operating and the main electorolytic capacitor is charged with high-voltage direct current. However, when the CHG signal is Low (0 V), the charging circuit does not operate.
1-1. Power switch
When the CHG signal switches to Hi, Q5407 turns ON and the charging circuit starts operating.
1-2. Power supply filter
C5401 constitutes the power supply filter. They smooth out ripples in the current which accompany the switching of the oscillation transformer.
1-3. Oscillation circuit
This circuit generates an AC voltage (pulse) in order to in­crease the UNREG power supply voltage when drops in cur­rent occur. This circuit generates a drive pulse with a frequency of approximately 50-100 kHz. Because self-excited light omis­sion is used, the oscillation frequency changes according to the drive conditions.
2. Light Emission Circuit
When RDY and TRIG signals are input from the ASIC expan­sion port, the stroboscope emits light.
2-1. Emission control circuit
When the RDY signal is input to the emission control circuit, Q5409 switches on and preparation is made to let current flow to the light emitting element. Moreover, when a STOP signal is input, the stroboscope stops emitting light.
2-2. Trigger circuit
When a TRIG signal is input to the trigger circuit, D5405 switches on, a high-voltage pulse of several kilovolts is gen­erated inside the trigger circuit, and this pulse is then applied to the light emitting part.
2-3. Light emitting element
When the high-voltage pulse form the trigger circuit is ap­plied to the light emitting part, currnet flows to the light emit­ting element and light is emitted.
Beware of electric shocks.
1-4. Oscillation transformer
The low-voltage alternating current which is generated by the oscillation control circuit is converted to a high-voltage alter­nating current by the oscillation transformer.
1-5. Rectifier circuit
The high-voltage alternating current which is generated at the secondary side of T5401 is rectified to produce a high­voltage direct current and is accumulated at electrolytic ca­pacitor C5412.
1-6. Voltage monitoring circuit
This circuit is used to maintain the voltage accumulated at C5512 at a constance level. After the charging voltage is divided and converted to a lower voltage by R5417, R5419 and R5420, it is output to the mi­croprocessor as the monitoring voltage VMONIT. When this VMONIT voltage reaches a specified level at the micropro­cessor, the CHG signal is switched to Low and charging is interrupted.
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Page 2
1-4. SYA CIRCUIT DESCRIPTION
1. Configuration and Functions
For the overall configuration of the SYA block, refer to the block diagram. The SYA block centers around a 8-bit microprocessor (IC301), and controls camera system condition (mode). The 8-bit microprocessor handles the following functions.
1. Operation key input, 2. Clock control and backup, 3. Power ON/OFF, 4. Storobe charge control, 5. Signal input and output for zoom and lens control.
Pin
1~4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24 VDD
25 AVSS
26 NOT USED
27~29 SCAN IN 0~2
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
/STBY_LED (GREEN)
Signal
/SCAN OUT 0~3
P ON
PA ON
BL_ON
LCD_ON
VSS
VDD
/SELF LED
/STBY_LED (RED)
/AVREF_ON
SI
SO
SCK
PRG SI
PRG SO
PRG SCK
NOT USED
NOT USED
CHG ON
NOT USED
NOT USED
CHG VOL
BATTERY
AVREF
AVDD
/RESET
XCOUT
XCIN
IC
XOUT
XIN
VSS
/BAT OFF
/SREQ
/SCAN IN3
SUB 1
/DC_IN
I/O
O
O
O
O
O
O
O
O
O
O
I/O
O
I/O
O
O
O
Outline
Key scan output
Digital power ON/OFF control H : ON
Analog power ON/OFF control H : ON
LCD backlight ON/OFF control H : ON
LCD power ON/OFF control H : ON
-
-
I
I
-
-
-
-
-
I
-
-
I
I
-
-
I
I
I
I
-
I
I
I
I
I
GND
VDD
Self LED (red) control L : ON
Stand-by LED (green) control L : ON
Stand-by LED (red) control L : ON
A/D converter standard voltage control L : ON
Receiving data (from ASIC)
Sending data (to ASIC)
Communication clock (to ASIC)
Flash memory writing receiving data
Flash memory writing sending data
Flash memory writing communication clock
-
-
Flash charge control H : ON
VDD
AVSS
-
Key scan input
-
-
Storobe charge voltage detection (analog input)
Battery voltage detection (analog input)
Analog standard voltage input terminal
A/D converter analog power terminal
Reset input
Clock oscillation terminal (37.768 kHz)
Clock oscillation terminal
Flash memory writing voltage
Main clock oscillation terminal (4MHz)
Main clock oscillation terminal
GND
Battery OFF detection
Serial communication requirement (from ASIC)
Key scan input 6
Command input (from ASIC)
DC jack/battery detection input
See next page
– 7 –
Page 3
48
49
50
51
52
53
54
55
56
57
58 NOT USED
59
60
61
62
63
64
BOOT
AV JACK I
NOT USED
/CARD
BUZZER
LCD ON2
ZTEST MODE
NOT USED
/BACKUP_CNT
/USB
NOT USED - -
CLKSEL 0
CLKSEL 1
PLLEN
ZTEST
/ASIC RESET
I/O
--
I
O
O
I
-
O
I
-
O
O CPU clock swtich control
O PLL reset signal L : RESET
O
O
Table 4-1. 8-bit Microprocessor Port Specification
Compulsion boot control L : DC JACK detection
AV jack connection detection H : AV jack detection
SD card insertion detection L : Insertion
Beep output
LCD power ON/OFF control 2
Test mode input L : Test mode
-
Backup battery charge control L : Charge ON
USB connector detection L : USB detecion
-
CPU clock ON/OFF control H : ON
ASIC reset signal L : RESET
CPU reset singal L : RESET
2. Internal Communication Bus
The SYA block carries out overall control of camera operation by detecting the input from the keyboard and the condition of the camera circuits. The 8-bit microprocessor reads the signals from each sensor element as input data and outputs this data to the camera circuits (ASIC) or to the LCD display device as operation mode setting data. Fig. 4-1 shows the internal communication between the 8-bit microprocessor, ASIC and SPARC lite circuits.
ZTEST
ASIC RESET
S. REQ
8-bit
Microprocessor
Fig. 4-1 Internal Bus Communication System
ASIC SO
ASIC SI
ASIC SCK
PLLEN
CLKSEL0
CLKSEL1
3. Key Operaiton
For details of the key operation, refer to the instruction manual.
SCAN
SCAN OUT
IN
0
0
REC
123
REC (VF)
ASIC
PLAY
1
2
3
WIDE
LEFT
1st SHUTTER
Table 4-2. Key Operation
TELE
UP
2nd SHUTTER
MENU
DOWN
FLASH
– 8 –
SET
RIGHT
POWER ON/OFF
Page 4
4. Power Supply Control
The 8-bit microprocessor controls the power supply for the overall system. The following is a description of how the power supply is turned on and off. When the battery is attached, a regulated 3.2 V voltage is normally input to the 8-bit microprocessor (IC301) by IC302, so that clock counting and key scanning is carried out even when the power switch is turned off, so that the camera can start up again. When the battery is removed, the 8-bit micro­processor operates in sleep mode using the backup lithium secondary battery. At this time, the 8-bit microprocessor only carries out clock counting, and waits in standby for the battery to be attached again. When a switch is operated, the 8-bit microprocessor supplies power to the system as required. The 8-bit microprocessor first sets both the P (A) ON signal at pin (6) and the P ON signal at pin (5) to high, and then turns on the DC/DC converter. After this, high signals are output from pins (60), (61), (62), (63) and (64) so that the ASIC is set to the active condition. If the LCD monitor is on, the LCD ON signal at pin (21) and the LCD ON 2 signal at pin (53) set to high, and the DC/DC converter for the LCD monitor is turned on. Once it is completed, the ASIC returns to the reset condition, all DC/DC converters are turned off and the power supply to the whole system is halted.
ASIC,
memory
Power voltage
Power OFF
Power save
CAMERA
Note) 4 MHz = Main clock operation, 32 kHz = Sub clock operation
Monitor OFF
LCD finder
Play back
Table 4-3. Camera Mode (Battery Operation)
3.3 V
OFF
OFF
OFF
ON
ON
CCD
-7.6 V (A)
+15 V (A) etc.
OFF
OFF
OFF
ON
OFF
8 bit
CPU
3.2 V
(ALWAYS)
32KHz OFF
4 MHz OFF
4 MHz OFF
4 MHz ON
4 MHz ON
MONITOR
+15 V (L)
+5V (L)
LCD
– 9 –
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