BD9778F-E2 View Datasheet(PDF) - ROHM Semiconductor

Part Name

Description

Manufacturer

BD9778F-E2

Flexible Step-down Switching Regulators with Built-in Power MOSFET

ROHM Semiconductor 

BD9778F, BD9778HFP, BD9001F, BD9781HFP

Technical Note

Block diagram / Application circuit / Pin assignment

(BD9778F)

(BD9778HFP)

GND EN

PVIN RT

SW INV

VIN FB

PVIN

8

VIN

1

220µF 1µF

SOFT

START

Vref

ON/OFF

L:OFF

H:ON

EN

5

23kΩ

INV

4

10kΩ

150kΩ

4700pF

ERROR AMP

-

+

-

+

+

Vref

OSC

PWM

COMPARATOR

LATCH

RESET

DRIVER

TSD

SW

2

VIN

3

FB

RT

6

+

-

CURRENT LIMIT

7

GND

33µH

VO

330µF

0.1µF

390kΩ

VIN FB INV EN

SW GND RT

VIN

1

220µF 1µF

SOFT

START

Vref

ON/OFF

L:OFF

H:ON

EN

7

23kΩ

INV ERROR AMP

5

-

+

-

10kΩ

+

+

150kΩ

Vref

4700pF

OSC

PWM

COMPARATOR

LATCH

RESET

DRIVER

TSD

SW

2

3

FB

RT

6

VIN

+

-

CURRENT LIMIT

4

GND

33µH

VO

330µF

0.1µF

390kΩ

Fig.23

No. Pin name

Function

1

VIN

Power supply input

2

SW

Output

3

FB

Error Amp output

4

INV

Output voltage feedback

5

EN

Enable

6

RT

Frequency setting resistor connection

7

GND Ground

8

PVIN Power system power supply input

Fig.24

No. Pin name

Function

1

VIN

Power supply input

2

SW

Output

3

FB

Error Amp output

4

GND Ground

5

INV

Output voltage feedback

6

RT

Frequency setting resistor connection

7

EN

Enable

FIN

-

Ground

(BD9001F)

(BD9781HFP)

GND EN

VIN RT

N.C. INV

SW FB

No.

1

2

3

4

5

6

7

8

VIN

8

220µF 1µF

SOFT

START

Vref

23kʎ

10kʎ

INV

4

150kʎ

4700pF

3

FB

ERROR AMP

-

+

-

+

+

Vref

OSC

PWM

COMPARATOR

LATCH

RESET

DRIVER

TSD

VIN

+

-

CURRENT LIMIT

RT

6

0.1µF

390kʎ

SW 33 µH

VO

1

330µF

7

GND

Fig.25

Pin name

SW

N.C.

FB

INV

EN

RT

GND

VIN

ýýýýýýFunction

Output

Non Connection

Error Amp Output

Output voltage feedback

Enable

Frequency setting resistor connection

Ground

Power supply input

VIN RT FB EN/SINC

SW GND INV

VIN

1

ON/OFF

L:OFF

H:ON

EN/

SYNC

7

220µF 1µF

SOFT

START

Vref SYNC

23kΩ

INV

6

10kΩ

150kΩ

ERROR AMP

-

+

+

Vref

PWM

COMPARATOR

-

LATCH

+

RESET

4700pF

OSC

DRIVER

TSD

SW

2

VIN

5

FB

RT

3

+

-

CURRENT LIMIT

4

GND

33µH

VO

330µF

0.1µF

390kΩ

Fig.26

No. Pin name

Function

1

VIN

Power supply input

2

SW

Output

3

RT

Frequency setting resistor connection

4

GND

Ground

5

FB

Error Amp output

6

INV

Output voltage feedback

7

EN/SYNC Enable/Synchronizing pulse input

FIN

-

Ground

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© 2010 ROHM Co., Ltd. All rights reserved.

6/16

2010.02 - Rev. B

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