Obsolete

Product(s)

- Obsolete

Product(s)

AN1645 - APPLICATION NOTE

18/22

Synchronization

Q7

Npn Transistor to turn off the device

R12

Base resistor for Q2

Resi stor Divider (Fig.6)

Pull-up resi stor (Fig. 7)

Com p D2

Small signal diode:

protects Ck pin from

voltages

higher than Vcc

Resistor:

Pull-up resistor

Com p C5

Capacitor:

to

acts

like

an

RC

filt er

to

eliminate

the

turn-off

voltage

spike

Not mounted

Com p R5

Resistor:

low side partition resistor

Not mounted

Com p R4

Resistor:

high side partition resistor

Diode:

small signal diode puts Ck pin to low level

when free-wheeling FE T is conducting

Com p R11

Not mounted

Not mounted

INHIBIT

R7

Limits the current flowing into INHIB IT pin when FW Drain voltage is higher

than Vcc

JP5

Close to operate in discontinuous mode condition

JP6

Close to provide constant negative volt age to Inhibit

Blanking Time (Fig.12)

Di sabling (Fig.14)

Com p C7

Capacitor:

Provides the negative voltage to

determine the blanking voltage

Small signal diode:

blocks the positive voltage on Inhibit pin

Com p D5

Resistor:

together with C7 determines the

time and voltage value of the

blanking circuit

Not mounted

Com p R9

Diode + resistor in series:

diode blocks the positive voltage;

resistor adds the negative voltage

to the Inhibit pin

Resistor:

Set the time constant to charge capacitor

C8

Com p R10

Not mounted

Not mounted

Com p C8

Not mounted

Capacitor:

Filter capacitor to keep constant the

voltage on Inhibit

Anticipation

R6, R8

Resistor divider which provides voltage level to set Anticipation time

JP4

Sets the maximum anticipation time

JP3

Sets the medium anticipation time

JP2

Sets the minimum anticipation time