14/16

Technical Note

Fig.36 Equivalent circuit

Fig.37 Typical simple construction of monolithic IC

P layer

E

B

C

(Pin B)

Transistor (NPN)

P

N

N

N

N

GND

Parasitic element

GND

P+

P+

(Pin A)

GND

Parasitic element

(PIN B)

GND

B

E

C

Parasitic element

P+

P layer

(Pin A)

Resistor

P

N

N

N

GND

Parasitic element

P+

Notes for use

1) Absolute maximum ratings

An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc.,

can break down the devices, thus making impossible to identify breaking mode, such as a short circuit or an open circuit.

If any over rated values will expect to exceed the absolute maximum ratings, consider adding circuit protection devices,

2) GND potential

GND potential should maintain at the minimum ground voltage level. Furthermore, no terminals should be lower than the GND

potential voltage including an electric transients.

3) Thermal design

Use a thermal design that allows for a sufficient margin in light of the power dissipation (Pd) in actual operating conditions.

4) Inter-pin shorts and mounting errors

Use caution when positioning the IC for mounting on printed circuit boards. The IC may be damaged if there is any connection

error or if positive and ground power supply terminals are reversed. The IC may also be damaged if pins are shorted

together or are shorted to other circuits power lines.

5) Operation in strong electromagnetic field

Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to malfunction.

6) Inspection with set printed circuit board

When testing the IC on an application board, connecting a capacitor to a pin with low impedance subjects the IC to stress.

Always discharge capacitors after each process or step. Always turn the IC's power supply off before connecting it to,

or removing it from a jig or fixture, during the inspection process. Ground the IC during assembly steps as an antistatic

measure. Use similar precaution when transporting and storing the IC.

VIN

EN/SYNC

222

k

Ω

221

k

Ω

2k

Ω

VREGA

139

k

Ω

145

k

Ω

SW

SW

EN

VIN

10k

Ω

300k

Ω

250k

Ω

VIN

2k

Ω

300k

Ω

50k

Ω

RT

VIN

VREF

VIN

EN/SYNC BD9781HFP

EN BD9778F/HFP, BD9001F

1k

Ω

VIN

FB

VREF

1k

Ω

INV

VIN

VREF

FB BD9778F/HFP, BD9781HFP

INV

RT

FB BD9001F

1k

Ω

VIN

FB

VREF

1k

Ω

2010.02 -

Rev. B

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BD9778F, BD9778HFP, BD9001F, BD9781HFP