AAT3192_08 Datasheet, PDF (10/18 Pages) Advanced Analogic Technologies – 2-Channel Charge-Pump LED Driver

ChargePump^TM
S2Cwire Serial Interface
(AAT3192-1/-2/-3 only)
The LED output current of the AAT3192 is controlled by
AnalogicTech’s S²Cwire serial interface. Since the LED
current is programmable, no PWM or additional control
circuitry is needed to control LED brightness. This feature
greatly reduces the burden on a microcontroller or sys-
tem IC to manage LED or display brightness, allowing the
user to “set it and forget it.” With its high-speed serial
interface (1MHz data rate), the LED current can be
changed quickly and easily. Also the non-pulsating LED
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
PRODUCT DATASHEET
AAT3192
2-Channel Charge-Pump LED Driver
by a pause with EN/SET held high for at least t_LAT (500μs).
The programmed current is then seen at the current sink
outputs. When EN/SET is held low for an amount of time
longer than t_OFF (500μs), the AAT3192 enters into shut-
down mode and draws less than 1μA from the input and
the internal data register is reset to zero.
The AAT3192-1/2/3’s serial interface reduces the LED
current on each rising pulse of the enable input. If the
AAT3192 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 AAT3192-1. For the
AAT3192-2, Table 2 and Figure 3 illustrate an 8-step LED
current control profile. For the AAT3192-3, Table 3 and
Figure 4 illustrate a 4-step LED current control profile.
EN/SET
Data Reg
T_HI
T_LO
T_LAT
1
2
n-1 n ≤ 16
0
T_OFF
n-1
0
Figure 1: S²C Serial Interface Timing.
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-D2 Current (mA)
20
18.7
17.3
16
14.7
13.3
12
10.7
9.3
8
6.7
5.3
4
2.7
1.3
0.63
Table 1: AAT3192-1 LED Current Settings.
20.00
15.00
10.00
5.00
0.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
S²Cwire Interface Data Code
Figure 2: AAT3192-1 Current Control Profile.
10
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3192.2008.07.1.3