Reset Circuit - Hitachi RAF-35NH5 Service Manual

. Reset Circuit

MODEL RAF- 5NH5, RAF-35NH5, RAF-50NH5
Timing chart
pin of IC5 1 supply voltage
②
pin of IC5 1 output voltage
①
or pin of microcomputer
⑦
Reset circuit is to initialize the indoor unit microcomputer when switching ON the power or after recovering from power
failure.
Microcomputer operates when
Waveform of each part when switching ON the power and when shutting down is shown in the Fig. - .
After switching ON the power,
approximately 4.4V or higher.
Then, resetting will be cancelled and microcomputer starts operating.
After shutting down the powe
approximately 4. V or lower.
Then, the microcomputer will be in reset condition.
5V
5
3
IC5 1
Voltage
5.0V
RES canceling voltage
4.4V
Voltage
5.0V
pin of the indoor unit microcomputer (reset input) is "Lo" for resetting and "Hi" for hitting.
⑦
pin of IC5 1 and
① ⑦
pin of IC5 1 and
r, ① ⑦
R5
1
0V
Fig. -1
Fig. -
pin of microcomputer becomes Hi when DC5V line rises and reaches
pin of microcomputer becomes Lo when DC5V line falls and reaches
- 242 -
Reset
7
Microcomputer
RES detecting voltage
4. V