AP6502

340kHz 23V 2A SYNCHRONOUS DC/DC BUCK CONVERTER

AP6502

Document Number: DS35423 Rev. 2 - 2

2 of 12

www.diodes.com

September 2011

© Diodes Incorporated

Pin Descriptions

Pin #

Name

Description

1

BS

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

switch. Connect a 0.01µF or greater capacitor from SW to BS to power the high side switch.

2

IN

Power Input. IN supplies the power to the IC, as well as the step-down converter switches.

Drive IN with a 4.75V to 23V power source. Bypass IN to GND with a suitably large capacitor

to eliminate noise on the input to the IC. See Input Capacitor.

3

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.

4

GND

Ground (Connect the exposed pad to Pin 4).

5

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 0.925V. See

Setting the Output Voltage.

6

COMP

Compensation Node. COMP is used to compensate the regulation control loop. Connect a

series RC network from COMP to GND. In some cases, an additional capacitor from COMP to

GND is required. See Compensation Components.

7

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 100k

Ω pull up resistor for automatic startup.

8

SS

Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from SS to GND

to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 15ms. To disable the

soft-start feature, leave SS floating.

Functional Block Diagram

Figure 3. Functional Block Diagram

E

+

-

+

-

+

-

+

-

+

-

+

1.1V

0.3 V

INTERNAL

REGULATORS

Logic

5V

SHUTDOWN

COMPARATOR

0.9V

+

-

ERROR

AMPLIFIER

LOCKOUT

COMPARATOR

8

7

5

100/340 KHz

OSCILLATOR

CURRENT

SENSE

AMPLIFIER

OVP

RAMP

CLK

CURRENT

COMPARATOR

EN OK

disable

IN < 4.10V

2

1

3

4

6

FB

6uA

EN

COMP

2.5V

SS

0.923 V

GND

SW

BS

IN

100m

Ω

100m

Ω

IN