Hitachi RAF-25NH5 Instructions De Service page 224

ODEL RAD-25NH5, RAD-35HN5, RAI-25NH5, RAI-35HN5, RAI-50HN5, RAK-18HN5, RAK-25HN5, RAK-35HN5, RAK-50HN5
. Reset Circuit
Timing chart
pin of IC521 supply voltage
②
pin of IC521 output voltage
①
or pin of micro computer
⑦
Reset circuit is to initialize the indoor unit micro computer when switching ON the power or after recovering from power
failure.
icro computer operates when
Waveform of each part when switching ON the power and when shutting down is shown in the Fig. 1-2.
After switching ON the power,
approximately 4.4V or higher.
Then, resetting will be cancelled and micro computer starts operating.
After shutting down the powe
approximately 4.2V or lower.
Then, the micro computer will be in reset condition.
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5V
2
5 1
3
IC521
Fig.1-1
Voltage
5.0V
RES canceling voltage
4.4V
Voltage
5.0V
Fig.1-2
pin of the indoor unit micro computer (reset input) is "Lo" for resetting and "Hi" for hitting.
⑦
pin of IC521 and pin of micro computer becomes Hi when DC5V line rises and reaches
① ⑦
pin of IC521 and pin of micro computer becomes Lo when DC5V line falls and reaches
r, ① ⑦
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R522
0V
Reset
7
icro computer
RES detecting voltage
4.2V