SM8172A

SEIKO NPC CORPORATION —2

6. PINOUT

(Top view)

7. PIN DESCRIPTION

8. BLOCK DIAGRAM

Number

Name

I/O

Function

1

VIN2

–

*1. VIN1 and VIN2 should have the same voltage potential.

2

LDOUT

O

*2. When the series regulator is not used, LDOUT pin should be open and not be connected to GND.

3

GND

–

Ground (internal circuits)

4

ENDCO

*3. Ip = Input with pull-down resistor built-in

Output enable (DC/DC converter)

5

ENLDO

Output enable (series regulator)

6

PGND

–

Ground (DC/DC converter output circuit)

7

LX

O

*4. When the DC/DC converter is not used, LX pin should be open and not be connected to GND or the supply.

8

VIN1

–

9

FB

I

*5. When the DC/DC converter is not used, FB pin should be connected to GND.

10

RESETN

O

*6. When the reset signal is not used, RESETN pin should be connected to GND.

10

9

8

7

6

1

2

3

4

5

VIN2

LDOUT

GND

ENDCO

ENLDO

RESETN

FB

VIN1

LX

PGND

VIN2

RESETN

Delay

circuits

Current

protection

ENDCO

GND

VIN2

detector

Soft

start

Vref

+

−

ERR

LDOUT

Thermal

protection

OSC

Soft

start

Current

protection

ERR

+

−

FB

Current mode

PWM control

Output

control

VIN1

LX

PGND

RESETN output

LDOUT output

(3.3V)

3.3

µF

5.0V

10

µF

2.2

µH

10k

Ω

4.7

µF

DCOUT

(1.0V)

10

µF

5.0V

ENLDO

8pF

220k

Ω

330k

Ω