PRODUCT DATASHEET
AAT3104178
TM
ChargePump
Low Cost 1x/2x 4 Channel Charge Pump WLED Driver
current reduces system noise and improves LED reliabil-
ity. The S2Cwire interface relies on the number of rising
edges to the EN/SET pin to set the register. A typical
write protocol is a burst of EN/SET rising edges, followed
by a pause with EN/SET held high for at least tLAT (500μs).
The programmed current is then seen at the current
source outputs. When EN/SET is held low for an amount
of time longer than tOFF (500μs), the AAT3104 enters into
shutdown mode and draws less than 1μA from the input
and the internal data register is reset to zero.
Data
EN Rising Edges
D1-D4 Current (mA)
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
9
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
The AAT3104-1/2’s serial interface reduces the LED cur-
rent on each rising pulse of the enable input. If the
AAT3104 is in shutdown, the first rising edge of the EN/
SET input turns on the LED driver to the maximum cur-
rent. Successive rising edges decrease the LED current
as shown in Table 1 and Figure 2 for the AAT3104-1. For
the AAT3104-2, Table 2 and Figure 3 illustrate a 32-step
LED current control profile.
EN Rising
Edges
D1-D4
Current (mA)
Data
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
30
28
26
24
22
20
18
16
14
12
10
8
8
7
6
5
4
3
2
1
0.5
Table 2: AAT3104-2 LED Current Settings.
6
4
2
0.5
Table 1: AAT3104-1 LED Current Settings.
tLO
t
HI
tOFF
OFF
2
3
OFF
1
Figure 1: EN/SET Timing Diagram.
w w w . a n a l o g i c t e c h . c o m
3104.2008.09.1.0
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