AP1510

PWM CONTROL 3A STEP-DOWN CONVERTER

AP1510 Rev. 1

4 of 8

JANUARY 2007

www.diodes.com

Typical Application Circuit

AP1510

+

-

V

SS

EN

C

C

R

A

R

B

D1

FB

Vcc

Output

CVcc

V

V

IN

R

OCSET

OCSET

C

OUT

C

IN

Optional

C

OCSET

C

EN

R

EN

Option

100K

Note: V

R

L1

22uH

6.8K

1.3K

3.9K

0.1uF

+

-

C

0.1uF

470uF

470uF

0.1uF

Figure 1.

2.5V

3.3V

5V

L1 Value

15uH

18uH

22uH

Function Description

PWM Control

The AP1510 consists of DC/DC converters that employ a

pulse-width modulation (PWM) system.

In converters of the AP1510, the pulse width varies in a range

from 0 to 100%, according to the load current. The ripple voltage

produced by the switching can easily be removed through a filter

because the switching frequency remains constant. Therefore,

these converters provide a low-ripple power over broad ranges of

input voltage and load current.

Under Voltage Lockout

The under voltage lockout circuit of the AP1510 assures that the

high-side MOSFET driver outputs remain in the off state

whenever the supply voltage drops below 3.3V. Normal operation

The current limit threshold is setting by the external resistor

current crossing the resistor sets the voltage at pin of OCSET.

When the PWM voltage is less than the voltage at OCSET, an

over-current condition is triggered.

R

I

R

I

OCSET

OCSET

DS(ON)

LOAD

×

=

×

See above formula for setting the current limit value.