AP2280

Single Channel Slew Rate Controlled Load Switch

AP2280 Rev. 6

8 of 12

FEBRUARY 2009

www.diodes.com

Input Capacitor

A 1

μF capacitor is recommended to connect

between IN and GND pins to decouple input power

supply glitch and noise. The input capacitor has no

specific type or ESR (Equivalent Series Resistance)

requirement.

However,

for

higher

current

application, ceramic capacitors are recommended

due to their capability to withstand input current

surges from low impedance sources, such as

batteries in portable applications. This input

capacitor must be located as close as possible to

the device to assure input stability and less noise.

For PCB layout, a wide copper trace is required for

both IN and GND.

Output Capacitor

A 0.1

μF capacitor is recommended to connect

between OUT and GND pins to stabilize and

accommodate load transient condition. The output

capacitor has no specific type or ESR requirement.

The amount of the capacitance may be increased

without limit. For PCB layout, the output capacitor

must be placed as close as possible to OUT and

GND pins, and keep the traces as short as

possible.

Enable/Shutdown Operation

The AP2280 is turned on by setting the EN pin high,

and is turned off by pulling it low. To ensure proper

operation, the signal source used to drive the EN

pin must be able to swing above and below the

specified turn-on/off voltage thresholds listed in the

Discharge Operation

The AP2280 offers discharge option that helps to

discharge the output when disabled. To use this

feature, the DIS pin is connected to OUT pin

externally. If this feature is not used, the DIS pin

should be left open.

Power Dissipation

The device power dissipation and proper sizing of

the thermal plane is critical to avoid thermal

shutdown and ensuring reliable operation. Power

dissipation of the device depends on input voltage

and load conditions and can be calculated by:

DSON

2

OUT

D

xR

I

P

=

(1)

However, the maximum power dissipation that can

be handled by the device depends on the

maximum junction to ambient thermal resistance,

maximum ambient temperature, and maximum

device

junction

temperature,

which

can

be

approximated by the equation below:

JA

A

A

D

)

T

C

125

(

)

T

(max@

P

θ

−

°

+

=

(2)

on

θ

junction

temperature

rise

from

ambient

is

approximately 51°C. Since the maximum junction

temperature is 125°C, the operating ambient

temperature must be kept below 74°C to safely

operate the device.

calculated

maximum

power

dissipation

from

operating maximum continuous current is 1.77A.

For other application conditions, the users should

recalculate the device maximum power dissipation

based on the operating conditions.

Application Note