FA5626 FUJI [Fuji Electric], FA5626 Datasheet - Page 20

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

(11)Brown-out
FA5626 has a brown-out function that stops switching operation when the AC input voltage drops below normal operating
voltage.Fig.14 shows input voltage waveform of VH pin. When VH pin voltage reached brown-in threshold voltage (DC 105V
typ.), switching operation is started.
When VH pin voltage drops below brown-out threshold voltage for longer than delay timer, brown-out function stops
switching operation.
In case of half wave input, the brownout timer is counted because VH pin voltage drops until 0 V at every period.
But brown-out function doesn’t operate because brown-out delay time longer than the half wave period.
Brown-out delay time depends on the oscillation frequency as shown in Fig.15.
Vcc voltage is maintained at between 12V and 13V by ON/OFF control of startup circuit when IC stops switching operation at
brown-out function, and IC restarts after VH pin voltage reached brown-in threshold voltage .
AN-071E Rev.1.2
April-2011
Fuji Electric Co., Ltd.
500
400
300
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0
0
Fig.15 Brown-out delay time
Fig.14 Brown-out operation
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Oscillation frequency [kHz]
FA5626
20
30
20
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60
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