AP3783

Document number: DS37429 Rev. 6 - 2

9 of 17

www.diodes.com

December 2015

© Diodes Incorporated

AP3783

Figure 2. The Operation Waveform of Flyback PSR System

linearly at a rate of:

M

IN

L

)

t

(

V

dt

)

t

(

dip



(1)

CS

CS

PK

R

V

I



(2)

2

PK

M

I

L

2

1

Eg







(3)

So the power transferring from the input to the output is given by:

SW

2

PK

M

f

I

L

2

1

P









(4)

Constant Voltage Operation

As to constant-voltage (CV) operation mode, the AP3783 detects the auxiliary winding voltage at FB pin to regulate the output voltage. The

auxiliary winding voltage is coupled with secondary side winding voltage, so the auxiliary winding voltage at D1 conduction time is:





D

O

S

AUX

AUX

V

V

N

N

V







(5)

t

ONP

t

ONS

t

OFFS

t

OFF

t

SW