AAT4296/98
Five/Six Channel Push/Pull I/O Expander
The output capacitor has no specific capacitor type
or ESR requirement. If desired, COUT may be
increased to a value greater than 0.1µF without
limit to accommodate any load transient condition
without adversely affecting the device turn-on slew
rate time.
Constants for the AAT4296 and AAT4298 are max-
imum junction temperature, TJ(MAX) = 125°C, and
package thermal resistance, θJA = 120°C/W. Worst-
case conditions are calculated at the maximum
operating temperature, where TA = 85°C. Typical
conditions are calculated under normal ambient
conditions, where TA = 25°C.
Thermal Considerations
At 25°C ambient, the AAT4296 is capable of dissi-
pating 440mW of power. If all five channels have
5.0V output, the average current is 121mA per
channel. The AAT4298 is capable of dissipating
625mW of power. If all six channels have 5.0V out-
put, the average current is 131.5mA per channel.
The AAT4296 and AAT4298 are designed to deliv-
er continuous output load currents. 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 need to be
taken into account.
At 85°C ambient, the AAT4296 is capable of dissi-
pating 177.78mW of power. If all five channels
have 5.0V output, the average current is 76.5mA
per channel. The AAT4298 is capable of dissipat-
ing 250mW of power. If all six channels have 5.0V
output, the average current is 83mA per channel.
At any given ambient temperature (TA), the maxi-
mum package power dissipation can be deter-
mined by the following equation:
TJ(MAX) - TA
PD(MAX)
=
θJA
Applications Circuit
VCC Input
OUT1
OUT2
OUT 1
OUT 2
VCC
AAT4298
OUT3
OUT4
OUT5
OUT6
OUT 3
OUT 4
OUT 5
OUT 6
EN/SET Input
EN/SET
GND
C1*
C2*
C3*
C4*
C5*
C6*
Figure 4: Typical Application Diagram.
*Use of capacitors on each output is optional.
4296.2006.12.1.3
13
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
