AAT3103IJQ-1-T1 AAT [Advanced Analog Technology, Inc.], AAT3103IJQ-1-T1 Datasheet - Page 10

• Manufacturer Part Number: AAT3103IJQ-1-T1
• Description: 3-Channel Charge-Pump LED Driver
• Manufacturer: AAT [Advanced Analog Technology, Inc.]

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 R
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
10
ChargePump
Data
Figure 3: AAT3103-2 Current Control Profile,
1
2
3
4
5
6
7
8
Table 2: AAT3103-2 LED Current Settings,
25
20
15
10
5
0
EN Rising Edges
1
2
TM
1
2
3
4
5
6
7
8
S
R
R
2
C Wire Interface Data Code
SET
SET
3
= 14.3kΩ.
= 14.3kΩ.
4
D1-D3 Current (mA)
5
6
20.1
17.5
14.8
12.1
1.34
9.4
6.7
4.0
7
w w w . a n a l o g i c t e c h . c o m
8
SET
.
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 500μs.
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
Figure 4: AAT3103-4 Current Control Profile,
Table 3: AAT3103-4 LED Current Settings,
3-Channel Charge-Pump LED Driver
25
20
15
10
5
0
100
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
R
R
90
SET
SET
= 14.3kΩ, f
= 14.3kΩ, f
80
PRODUCT DATASHEET
70
PWM Duty Cycle (%)
60
PWM
PWM
D1-D3 Current (mA)
AAT3103
50
= 25kHz.
= 25kHz.
40
3103.2008.03.1.0
20.2
18.2
16.2
14.3
12.3
10.4
6.55
8.5
4.6
2.6
30
20
10