AP65450

Document number: DS39860 Rev. 2 - 2

2 of 15

www.diodes.com

August 2017

© Diodes Incorporated

AP65450

Typical Applications Circuit

AP65450

L1

1.5

μH

R1

8.25k

Ω

R2

22.1k

Ω

C5

0.1µF

C2

44

μF

C1

20

μF

C4

8.2nF

ON

OFF

8

VIN

4

SS

1

EN

3

VREG5

6

SW

7

BST

2

FB

C3

1µF

9

PGND

INPUT

OUTPUT

1.05V

12V

5

GND

Figure 1 Typical Application Circuit

Pin Descriptions

Pin

Name

Pin Number

Function

SO-8EP

EN

1

Enable input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator, drive it low

to turn off. Pull

up with 100kΩ resistor for automatic startup.

FB

2

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

it from the output voltage.

VREG5

3

Internal power supply output pin to connect an additional capacitor. Connect a

1μF (typical) capacitor as close as

possible to the VREG5 and PGND. This pin is not active when EN is low.

SS

4

Soft-start control input pin. SS controls the soft start period. Connect a capacitor from SS to GND to set the soft-start

period.

GND

5

Ground pin is the main power ground for the switching circuit.

SW

6

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 BST to power the high-side switch.

BST

7

Bootstrap pin. A bootstrap capacitor is connected between the BST pin and SW pin. The voltage across the

bootstrap capacitor drives the internal high-side NMOS switch. A

0.1μF (typical) capacitor is required for proper

operation

VIN

8

Supply input pin. A capacitor should be connected between the VIN pin and PGND pin to keep the DC input voltage

constant.

EP

9 (Exposed

Pad)

Power ground. Exposed pad must be connected to a single point GND and as large of PGND plane as possible for

maximum thermal performance.