7

s Example of Printed-circuit board

The efficiency depends on the input voltage and the

output current. Thus, obtain the value from the

efficiency graph on page 8 and substitute the per-

centage in the formula above.

SFPB54-0.3V

rately.

s Selecting external components

1. Inductor L1

q It must be suited for switching regulators.

Do not use inductors for noise filters as they generate excessive heat.

w It must have the appropriate inductance value.

If the inductance is too small (150

µH or lower), abnormal oscillation may occur causing operation problems in

the overcurrent protection circuit within the rated current range.

e The rated current must be satisfied.

If the rated current is exceeded, magnetic saturation leads to overcurrent.

2. Capacitors C1 and C2

q They must satisfy the breakdown voltage and allowable ripple current.

Use of these capacitors over their derating values shortens their service lives and may also cause abnormal

oscillation of the IC.

operation.

3. Diode D1

of a Schottky barrier diode and make sure that the reverse voltage applied to terminal 2 of the IC does not exceed

the value (–1V) given in the absolute maximum ratings. If you use a fast recovery diode or any other diode, application

of a reverse voltage generated from the recovery or ON voltage of the diode may damage the IC.

a) For optimum operation,

there must be only one

GND line originating from

terminal 4 and each com-

ponent must be con-

nected with the shortest

possible wiring.

b) To prevent heating of the

IC, it is best to make the

GND pattern larger since

the internal frame and ter-

minal 4 (GND) are con-

nected to each other.

s Standard External Circuit

s Ta-PD Characteristics

+

C1

C

2

GND

SW

1

2

3

4

SAI

C1

D1

L1

µH

µH

100

µF

C2

330

µF

DC Input

DC Output

SFPB54

(Sanken)

GND

GND

GND

SAI

SW

12

3

4

+

+

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

-30

0

25

50

75

100

125

• Glass epoxy substrate

(95

× 69 × 1.2)

• Natural cooling

Ambient temperature Ta (

°C)

1–

100

–1