AP5100

1.2A Step-Down Converter with 1.4MHz Switching

Frequency

AP5100

Document number: DS32130 Rev. 2 - 2

3 of 10

www.diodes.com

November 2010

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Pin Descriptions

Pin Name

Pin #

Description

BST

1

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

GND

2

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.

FB

3

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

comparator lowers the oscillator frequency when the FB voltage is below 400mV.

EN

4

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.

IN

5

Supply Voltage. The AP5100 operates from a +4.75V to +24V unregulated input. A decoupling

capacitor C1 is required to prevent large voltage spikes from appearing at the input. Place this

capacitor near the IC.

SW

6

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

Functional Block Diagram

Figure 5. Functional Block Diagram