PRODUCT DATASHEET
AAT3103
ChargePumpTM
3-Channel Charge-Pump LED Driver
cycle of the PWM signal from 100% (logic high) to 10%,
the LED current can be programmed from 20mA to
2.6mA. To save power when not used, the AAT3103-4 can
be shut down by holding the EN/PWM pin low for 500ꢀs.
Data
EN Rising Edges
D1-D3 Current (mA)
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
20.1
17.5
14.8
12.1
9.4
6.7
4.0
1.34
Lastly, Table 3 and Figure 4 illustrate the AAT3103-4’s
LED current control profile as a function of a PWM con-
trol signal.
EN/PWM Duty Cycle
D1-D3 Current (mA)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
20.2
18.2
16.2
14.3
12.3
10.4
8.5
6.55
4.6
2.6
Table 2: AAT3103-2 LED Current Settings,
RSET = 14.3kΩ.
25
20
15
10
5
Table 3: AAT3103-4 LED Current Settings,
RSET = 14.3kΩ, fPWM = 25kHz.
0
1
2
3
4
5
6
7
8
25
20
15
10
5
S2C Wire Interface Data Code
Figure 3: AAT3103-2 Current Control Profile,
RSET = 14.3kΩ.
PWM Control (AAT3103-4 only)
PWM (Pulse Width Modulation) is a technique of control-
ling LED brightness by modulating the conduction duty
cycle of the LED current. LED brightness is determined by
the PWM duty cycle and FS (Full Scale) and LSB (the least
LED current). The FS LED current is determined by RSET.
The LSB LED current value is equal to the FS value divid-
ed by 30. A PWM control signal can be applied into the
EN/PWM pin of the AAT3103-4. By changing the duty
0
100
90
80
70
60
50
40
30
20
10
PWM Duty Cycle (%)
Figure 4: AAT3103-4 Current Control Profile,
RSET = 14.3kΩ, fPWM = 25kHz.
w w w . a n a l o g i c t e c h . c o m
10
3103.2008.03.1.0
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
