• Setting of oscillation frequency (BD9851EFV)

• Setting of timer of short circuit protection circuit (BD9851EFV)

• Setting of maximum duty (BD9851EFV)

• Pin treatment of unused channels (BD9851EFV)

In order to use one channel, treat the pins of unused channel as shown above.

Setting procedure

Application

SCP (14)

Setting procedure

Application

R1

R2

DTC (13)(7)

11/16

5

(18)

Vcc

(18)

Vcc

(17)

SEL1

(1)

NON2

(4)

INV

(16)

(5)

FB

(15)

(6)

DTC

(13)

(7)

OUT

(9)

PVcc

(12)

(11)

(8)

Upper : Pin No. to be treated when the CH1 is not used

Lower : Pin No. to be treated when the CH2 is not used

Fig. 22 Pin treatment procedure for unused channel on BD9851EFV

Connecting a resistor to the RT pin (pin 2) and a capacitor to the CT pin allows

for the setting of oscillation frequency.

Fig. 19 Setting procedure for BD9851EFV oscillation frequency

RT (2)

CT (3)

1000

1000

100

10

1

10

100

Timing Resistance (kΩ)

Fig. 20 RT vs. Oscillation frequency

1000

1000

100

10

10

10

100

1000

Timing Capacitance(pF)

Fig. 20 CT vs. Oscillation frequency

Time from output short circuit to latch stop [sec]

Capacitance of capacitor between the SCP and

GND pins [F]

DUTY(max.) = 100

× R2 / (R1 + R2)

DUTY(max.)

Vth0

Vth100

: Maximum duty [%]

: DTC pin voltage [V]

: 0% duty threshold voltage [V]

: 100% duty threshold voltage [V]