13

Applications Information (continued)

Application Circuit for Alternate Input voltages

The typical applications circuit for the SC4540 is shown in

Figure 2. The performance data and specifications included

in this document are for the typical application circuit

(Figure 2). The SC4540 can be used with input voltages

lower than 4.5V (see Figure 3). The Inductor, L1, will need

to be adjusted to allow proper operation for input volt-

ages between to 2.8V to 5.5V. The SC4538 datasheet

should be consulted for the performance of the lower

input voltage circuit.

OU T

LX

BL

4.5 to 12V

IN

EN

ISET

GN D

COM P

E nable and

PW M

dim m ing

L1

D

SC 4540

1 μF

56μH

2.2μF

1.27kΩ

47n F

Figure 2 — Typical Application Circuit

OU T

LX

BL

2.2μF

2.8V to 5.5V

IN

EN

ISET

GN D

COM P

E nable and

PW M

dim m ing

22μH

D

1 μF

1.27kΩ

SC 4540

L1

47n F

Figure 3 — Low Input Voltage Application Circuit

SC4540