AAT4282A

Dual Slew Rate Controlled Load Switch

10

4282A.2007.09.1.1

the internal parasitic diode and allow excessive

current flow into the VOUT pin, possibly damaging

the load switch. In applications where there is a

possibility of V

time during normal operation, the use of a larger

value C

er value of C

slower C

venting V

where there is a greater danger of V

V

ed to place a Schottky diode from V

necting the cathode to V

Schottky diode forward voltage should be less than

0.45V.

Thermal Considerations and High

Output Current Applications

The AAT4282A is designed to deliver a continuous

output load current. The limiting characteristic for

maximum safe operating output load current is

package power dissipation. In order to obtain high

operating currents, careful device layout and circuit

operating conditions must be taken into account.

The following discussions will assume the load

switch is mounted on a printed circuit board utilizing

the minimum recommended footprint as stated in

the Printed Circuit Board Layout Recommendations

section of this datasheet.

At any given ambient temperature (T

mum package power dissipation can be deter-

mined by the following equation:

Constants for the AAT4282A are maximum junction

temperature (T

mal resistance (

θ

tions are calculated at the maximum operating tem-

perature, T

lated under normal ambient conditions where T

25°C. At T

25°C, P

The maximum continuous output current for the

AAT4282A is a function of the package power dis-

sipation and the R

maximum RDS of the MOSFET at T

lated by increasing the maximum room tempera-

ture R

temperature coefficient (TC) is 2800ppm/°C.

Therefore, at 125°C:

R

R

R

For maximum current, refer to the following equation:

For example, if V

T

rent were to exceed 2.93A or if the ambient tem-

perature were to increase, the internal die temper-

ature would increase and the device would be

damaged. Higher peak currents can be obtained

with the AAT4282A. To accomplish this, the device

thermal resistance must be reduced by increasing

the heat sink area or by operating the load switch

in a duty cycle manner. Duty cycles with peaks less

than 2ms in duration can be considered using the

method described in the High Peak Current

Applications section of this datasheet.

<

=

1 The actual maximum junction temperature of AAT4282A is 150°C. However, good designed practice is to derate the maximum die tem-

perature down to 125 °C to prevent the possibility of over-temperature damage.