Sharp R-380A, Service Manual

Page: 19 / 40

R-380A
17
DESCRIPTION OF LSI
LSI(IZA778DR):
The I/O signal of the LSI(IZA778DR) is detailed in the following table.
Pin No. Signal I/O Description
A
B
0.12 sec.
2.4 sec.
H : GND
L : -5V
H : GND
L : -5V
1 C1 IN Terminal not used.
2 VL1 IN Power source voltage input terminal.
Standard voltage for LCD.
3-6 AN7-AN4 IN Terminal to change cooking constant according to the Model.
By using the A/D converter contained in the LSI, DC voltage in accordance with the
Model in operation is applied to set up its cooking constant.
7 AN3 OUT Terminal not used.
8 AIN2 IN To input signal which communicates the door open/close information to LSI.
Door closed; "H" level signal (0V).
Door opened; "L" level signal (-5V).
9 AN1 IN AH sensor input.
This input is an analog input terminal from the AH sensor circuit, and connected
the A/D converter built into the LSI.
10 AN0 IN Used for initial balancing of the bridge circuit (absolute humidity sensor). This input
is an analog input terminal from the AH sensor circuit, and connected to the A/D
converter built into the LSI.
11-13 P57-P55 OUT Terminal not used.
14 P54 OUT Signal to sound buzzer (2.0kHz).
A: key touch sound.
B: Completion sound.
15-18 P53-P50 OUT Terminal not used.
19-23 P47-P43 OUT Used for initial balancing of the bridge circuit (absolute humidity sensor).
24 INT0 IN Signal synchronized with commercial power source frequency.
This is the basic timing for time process-
ing of LSI.
25-26 P41-P40 OUT Terminal not used.
27 P77 IN Signal coming from touch key.
When either G12 line on key matrix is touched, a corresponding signal out of P20
- P27 will be input into P77. When no key is touched, the signal is held at "H" level.
28 P76 IN Signal similar to R77.
When either G11 line on key matrix is touched, a corresponding signal will be input into R76.
29 P75 IN Signal similar to R77.
When either G10 line on key matrix is touched, a corresponding signal will be input into R75.
30 P74 IN Signal similar to R77.
When either G9 line on key matrix is touched, a corresponding signal will be input into R74.
31 P73 OUT Oven lamp, fan motor and turntable motor driving signal.
To turn on and off the shut-off relay (RY1).
The square waveform voltage is delivered
to the relay RY1 driving circuit and RY2
control circuit.
32 P72 OUT Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay
(RY2). The signals holds "L" level
during microwave cooking and "H"
level while not cooking. In other cook-
ing modes (variable cooking) the sig-
nal turns to "H" level and "L" level in
repetition according to the power level.
33 P71 OUT Terminal not used.
34 P70 IN Connected to VC.
35 RESET IN Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is supplied.
Temporarily set to "L" level the moment power is supplied, at this time the LSI is
reset. Thereafter set at "H" level.
20.0 msec.
H : GND
L : -5V
20.0 msec.
During cooking
H : GND
L : -5V
P-HI
H : GND
L : -5V
H : GND
L : -5V
P-70
ON
ON
OFF
OFF OFF
24 sec.
8 sec.