PRODUCT DATASHEET
AAT3195
TM
ChargePump
4-Channel Charge-Pump LED Driver
THI
TOFF
TLO
TLAT
EN/SET
1
2
n-1
n ≤ 32
Data Reg
0
n-1
0
Figure 1: S2Cwire Serial Interface Timing.
AAT3195-1
EN Rising D1-D4 Current D1-D4 Current
AAT3195-2
35
AAT3195-1
AAT3195-2
30
25
20
15
10
5
Data
Edges
(mA)
(mA)
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
30.0
29.0
28.1
27.1
26.1
25.1
24.2
23.2
22.3
21.3
20.3
19.4
18.4
17.4
16.5
15.5
14.5
13.6
12.6
11.6
10.7
9.7
20.5
19.8
19.2
18.5
17.8
17.2
16.5
15.8
15.2
14.5
13.9
13.2
12.5
11.9
11.2
10.6
9.9
9.2
8.6
7.9
7.3
6.6
5.9
5.3
4.6
0
1
3
5
7
9
11 13 15 17 19 21 23 25 27 29 31
9
9
2
S Cwire Serial Interface Data Code
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
Figure 2: AAT3195-1/-2 Current Control Profile
PWM Control (AAT3195-3 only)
PWM (Pulse Width Modulation) is an industry-standard
technique of controlling LED brightness by modulating
the conduction duty cycle of the LED current. LED bright-
ness is determined by the average value of the PWM
signal multiplied by the LED’s intensity where intensity is
proportional to the LED drive current. A PWM control
signal can be applied to the EN/PWM pin of the AAT3195-
3. By changing the duty cycle of the PWM signal from
100% (logic high) to 10%, LEDs sink current can be pro-
grammed from 30mA to 3.0mA. To save power when not
used or not needed, the AAT3195-3 can be shut down by
holding the EN/PWM pin low for >1ms.
8.7
7.7
6.8
5.8
4.8
3.9
2.9
1.9
4.0
3.3
2.6
2.0
1.3
0.7
0.3
Lastly, Table 2 and Figure 3 illustrate the AAT3195-3's
LED current control profile as a function of a PWM control
signal.
1.0
0.5
Table 1: AAT3195-1/-2 LED Current Setting.
w w w . a n a l o g i c t e c h . c o m
10
3195.2008.09.1.0
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
