AP65211A

Document number: DS39744 Rev. 1 - 2

2 of 13

www.diodes.com

June 2017

© Diodes Incorporated

AP65211A

Pin Descriptions

Pin Number

Pin Name

Function

1

GND

Ground

2

SW

Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter

from SW to the output load. Note that a capacitor is required from SW to BS to power the high-side switch.

3

IN

Power Input. IN supplies the power to the IC, as well as the step-down converter switches. Drive IN with a 4.5V to

18V power source. Bypass IN to GND with a suitably large capacitor to eliminate noise on the input to the IC. See

Input Capacitor.

4

FB

Feedback Input. FB senses the output voltage and regulates it. Drive FB with a resistive voltage divider

connected to it from the output voltage. The feedback threshold is 0.8V. See Setting the Output Voltage.

5

EN

Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator; low to

turn it off. Attach to IN with a 100kΩ pull up resistor for automatic startup.

6

BST

High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET a 0.01µF or

greater capacitor from SW to BS to power the high side switch.

Functional Block Diagram

Internal

Reference

0.4V

0.8V

1.1V

Regulator

+

-

+

-

+

-

-

+

1.1V

0.4V

+

0.8V

Internal SS

Error

Amplifier

OVP

PWM

Comparator

Oscillator

500kHz

+

Logic

Ref

OCP

62pF

650k

1pF

UVP

HS

LS

4

5

EN

FB

1

GND

2

SW

6

BST

3

IN

Figure 2. Typical Application Circuit