CP-850FX Service Manual
Europe R&D
69
The time until the latch protection operation starts its operation can be calculated from the
following formula since the ISSOLP(OLP) is a constant current circuit. That is,
C (Condenser Capacity) x ⊿V(Condenser Charging Voltage: approx. 5V) = ISSOLP (OLP) x t (time)
…… (2)
While, the ISSOLP(OLP) contains the voltage dependent characteristics on SS/OLP terminal
voltage, and ISSOLP(OLP) falls when SS/OLP terminal voltage rises. The actual value does not
match to the value calculated from the formula (2) completely, so it is recommended to monitor
the actual load conditions. Furthermore, the power supply start-up voltage turning OCP
operation is also needed to confirm.
5.10.2.3 Operation at Power Supply OFF
The voltage of the condenser mounted externally to SS/OLP terminal is discharged by the
internal reset circuit of the HIC at power OFF. The reset circuit does not start its operation at
normal operation (i.e., while the internal constant voltage circuit operates).
5.10.2.4 Cancellation of OLP Circuit
The OLP operation is cancelled by inserting a resistor having 47K ohms (or Zener diodes) into
SS/OLP terminal at start-up or overload maintaining Soft-Start operation effectively.
図 11 OLP 禁止回路
図 10 リセット回路
PowerOff時
Reset回路
55
SS/OLP
55
SS/OLP
Fig.11. OLP Cancellation Circuit
Reset Circuit at Power
Off
Fig.10. Reset Circuit
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