AAT3192 Datasheet, PDF (10/17 Pages) Advanced Analogic Technologies – Low-Cost, 2-/3-Channel Charge-Pump LED Drivers

AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
S²Cwire Serial Interface
(AAT3192/93-1/-2/-3 only)
The LED output current of AAT3192/93 is con-
trolled 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 system IC to man-
age LED or display brightness, allowing the user to
"set it and forget it." With its high-speed serial inter-
face (1MHz data rate), the LED current can be
changed quickly and easily. Also the non-pulsating
LED current reduces system noise and improves
LED reliability. 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 by a pause with
EN/SET held high for at least t_LAT (500µs). The pro-
grammed 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 AAT3192/93
enters into shutdown mode and draws less than
1µA from the input and the internal data register is
reset to zero.
The AAT3192/93-1/2/3's serial interface reduces the
LED current on each rising pulse of the enable input.
If the AAT3192/93 is in shutdown, the first rising edge
of the EN/SET input turns on the LED driver to the
maximum current. Successive rising edges decrease
the LED current as shown in Table 1 and Figure 2 for
the AAT3192/93-1. For the AAT3192/93-2, Table 2
and Figure 3 illustrate an 8-step LED current control
profile. For the AAT3192/93-3, Table 3 and Figure 4
illustrate a 4-step LED current control profile.
EN/SET
T_HI
T_LO
T_LAT
1
2
n-1 n ≤ 16
T_OFF
Data Reg
0
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-D3
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: AAT3192/93-1 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: AAT3192/93-1 Current Control Profile
10
3193.2007.05.1.0