AAT4290/91
I/O Expander Load Switches with Serial Control
effect after the EN/SET pin has remained in a high
state for T
LAT
. The AAT4290 is disabled after the
EN/SET pin has transitioned and remained in a
logic low state for T
O
.
With the exception of three channel power switch-
es, the AAT4291 has a similar function to the
AAT4290. The ON/OFF state of the three MOS-
FET switches are controlled by the EN/SET serial
data input. An internal control counter is clocked
on the rising edge of the EN/SET pin and is decod-
ed into the eight possible states of the MOSFET
(see Table 2). The counter rolls over after eight
clocks and the table repeats.
Clock OUT5 OUT4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
on
on
on
on
on
on
on
on
on
on
on
on
on
on
on
on
off
off
off
off
off
off
off
off
off
off
off
off
off
off
off
off
on
on
on
on
on
on
on
on
off
off
off
off
off
off
off
off
on
on
on
on
on
on
on
on
off
off
off
off
off
off
off
off
OUT3
on
on
on
on
off
off
off
off
on
on
on
on
off
off
off
off
on
on
on
on
off
off
off
off
on
on
on
on
off
off
off
off
OUT2 OUT1
on
on
off
off
on
on
off
off
on
on
off
off
on
on
off
off
on
on
off
off
on
on
off
off
on
on
off
off
on
on
off
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
on
off
Clock
1
2
3
4
5
6
7
8
OUT3
on
on
on
on
off
off
off
off
OUT2
on
on
off
off
on
on
off
off
OUT1
on
off
on
off
on
off
on
off
Table 2: AAT4291 Output Settings.
Applications Information
Thermal Considerations
The AAT4290 is designed to deliver continuous
output load currents. Due to its high level of inte-
gration, care must be taken in designing for higher
load conditions. If greater loads are required, out-
puts can be tied together to deliver higher power to
a given load.
At 25°C ambient, the AAT4290 is capable of dissi-
pating 440mW of power, or 1.14A at 5.0V, for an
average current of 228mA per output.
At 85°C ambient, the AAT4290 is capable of dissi-
pating 178mW of power, or 0.72A at 5.0V, for an
average current of 145mA per output.
Table 1: AAT4290 Output Settings.
4290.2006.03.1.2
9
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
