AP5101

1.5A Step-Down Converter with 1.4MHz Switching

Frequency

AP5101

Document number: DS32258 Rev. 1 - 2

3 of 15

www.diodes.com

July 2010

© Diodes Incorporated

Pin Descriptions

SO-8

( Top View )

1

2

3

4

8

7

6

5

GND

BST

FB

COMP

SW

GND

EN

IN

Pin Name

Pin Number

Descriptions

SW

1

Switch Output. This is the reference for the floating top gate driver.

IN

2

Supply Voltage. The AP5101 operates from a +4.75V to +22V unregulated

input. A decoupling capacitor C1 is required to prevent large voltage spikes

from appearing at the input. Place this capacitor near the IC.

EN

3

On/Off Control Input. Do not leave this pin floating. To turn the device ON, pull

EN above 1.2V and to turn it off pull below 0.4V.

If enable/disable is not used, connect a 100k

Ω resistor between EN to V

GND

4

Ground. This pin is the voltage reference for the regulated output voltage. For

this reason care must be taken in its layout. This node should be placed

outside of the D1 to C1 ground path to prevent switching current spikes from

inducing voltage noise into the part.

FB

5

Feedback. To set the output voltage, connect this pin to the output resistor

limit condition, the frequency foldback comparator lowers the oscillator

frequency when the FB voltage is below 400mV.

COMP

6

Compensation. COMP is used to compensate the regulation control loop.

Connect a series RC network from COMP to GND.

BST

7

Bootstrap. To form a boost circuit, a capacitor is connected between SW and

BST pins to form a floating supply across the power switch driver. This

capacitor is needed to drive the power switch’s gate above the supply voltage.

GND

8

Ground. This pin is the voltage reference for the regulated output voltage. All

control circuits are referenced to this pin. For this reason care must be taken in

its layout.