AP1513

PWM CONTROL 2A STEP-DOWN CONVERTER

AP1513 Rev. 1

6 of 8

JANUARY 2007

www.diodes.com

Test Circuit

A

FB

VCC

VSS

EN

open

open

FB

VCC

VSS

EN

+

-

OUTPUT

OUTPUT

A

FB

VCC

VSS

EN

+

-

+

-

V

OUTPUT

OCSET

OCSET

OCSET

Enable function test

Feedback function test

Operation function test

1K

3K

1.2K

6.8K

1K

33K

Function Description

PWM Control

The AP1513 consists of DC/DC converters that employ a

pulse-width modulation (PWM) system.

In converters of the AP1513, 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 AP1513 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 the 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.