Hitachi RAF-25NH4 Données Techniques page 151

2. Reset Circuit
Timing chart
pin of IC521 supply voltage
②
pin of IC521 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. 2-2.
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 4.2V or lower.
Then, the microcomputer will be in reset condition.
5V
2
5
3
IC521
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 IC521 and
① ⑦
pin of IC521 and
r, ① ⑦
R522
1
0V
Fig.2-1
Fig.2-2
pin of microcomputer becomes Hi when DC5V line rises and reaches
pin of microcomputer becomes Lo when DC5V line falls and reaches
170
Reset
7
Microcomputer
RES detecting voltage
4.2V