FA5626 FUJI [Fuji Electric], FA5626 Datasheet - Page 18

• Manufacturer Part Number: FA5626
• Description: Fuji Switching Power Supply Control IC
• Manufacturer: FUJI [Fuji Electric]

(5) Overload protection circuit
AN-071E Rev.1.2
April-2011
When output current increases by the overload, MOSFET current is limited by the maximum threshold voltage (-0.5V typ.)
FA5626 integrates auto-restart mode overload protection function.
Fig. 10 shows the circuit block diagram and Fig. 11 shows the protection timing chart.
of IS pin. The output voltage is drops because of current limit and FB pin voltage rises. When FB pin voltage is over the
threshold voltage (VthOLP), overload is detected. After the overload is detected, internal OLP timer starts counting for the
delay time. When OLP delay time (70 msec typ.) has elapsed, the IC stops switching operation and MOSFET is kept off
state. When the self-return wait time (1530 ms typ.) has elapsed thereafter, IC re-starts switching operation automatically.
IC repeats stop and restart switching operation until overload condition is removed.
Vcc voltage is maintained at between 12V and 13V by ON/OFF control of startup circuit when IC stops switching
operation at overload.
Fuji Electric Co., Ltd.
Fig.11 Overload protection timing chart (auto recovery)
Fig.10 Overload protection circuit (auto recovery)
FA5626
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