PRODUCT DATASHEET
AAT3103
ChargePump
TM
Part Number Descriptions
Part Number
AAT3103IJQ-1
AAT3103IJQ-2
AAT3103IJQ-4
3-Channel Charge-Pump LED Driver
changed quickly and easily. Also the non-pulsating LED
current reduces system noise and improves LED reliabil-
ity. The S
2
Cwire 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 t
LAT
(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 t
OFF
(500μs), the AAT3103 enters into
shutdown mode and draws less than 1μA from the input
and the internal data register is reset to zero.
The AAT3103-1/-2’s serial interface reduces the LED cur-
rent on each rising pulse of the enable input. If the
AAT3103 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 AAT3103-1. For the
AAT3103-2, Table 2 and Figure 3 illustrate an 8-step LED
current control profile.
.
Interface
S
2
Cwire
S
2
Cwire
PWM
Current Control,
Inverting
16-step
8-step
Linear
S
2
Cwire Serial Interface
(AAT3103-1/-2 only)
The LED output current of the AAT3103-1/-2 is controlled
by AnalogicTech’s S
2
Cwire serial interface. Since the LED
current is programmable, no PWM or additional control
circuitry is needed to control the LED brightness. This
feature greatly reduces the burden on a microcontroller
or system IC to manage LED or display brightness, allow-
ing the user to “set it and forget it.” With its high-speed
serial interface (1MHz data rate), the LED current can be
T
HI
T
LO
T
LAT
T
OFF
EN/SET
1
2
n-1
n
≤
16
Data Reg
0
n-1
0
Figure 1: S
2
Cwire Serial Interface Timing.
S
2
C Data
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
EN Rising Edges
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
D1-D3 Current (mA)
20.1
18.8
17.5
16.1
14.8
13.4
12.1
10.7
9.4
8.1
6.7
5.4
4.0
2.7
1.34
0.67
Dx LED Current (mA)
25
20
15
10
5
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
S
2
C Wire Interface Data Code
Figure 2: AAT3103-1 Current Control Profile,
R
SET
= 14.3kΩ.
Table 1: AAT3103-1 LED Current Settings,
R
SET
= 14.3kΩ.
3103.2008.03.1.0
www.analogictech.com
9
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
