AAT3132ITP-T1(2004) View Datasheet(PDF) - Analog Technology Inc
Part Name
Description
MFG CO.
AAT3132ITP-T1
(Rev.:2004)
(Rev.:2004)
Analog Technology Inc
AAT3132ITP-T1 Datasheet PDF : 14 Pages
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AAT3132
High Efficiency 1.5X Fractional Charge
Pump for White LED Applications
Table 1: Constant Current Source
Output Programming Levels (mA)
Current Level Settings
Address D1-3 D4 (AAT3132) D4(AAT3132-1)
1
0.0
0
0
2
0.5
0
0
3
1.3
0
0
4
3.3
0
0
5
8.3
0
0
6
11.1
0
0
7
15.0
0
0
8
20.0
0
0
9
0.0
1
15
10
0.5
1
15
11
1.3
1
15
12
3.3
1
15
13
8.3
1
15
14
11.1
1
15
15 15.0
1
15
16 20.0
1
15
17
0.0
15
20
18
0.5
15
20
19
1.3
15
20
20
3.3
15
20
21
8.3
15
20
22
11.1
15
20
23 15.0
15
20
24 20.0
15
20
25
0.0
30
25
26
0.5
30
25
27
1.3
30
25
28
3.3
30
25
29
8.3
30
25
30
11.1
30
25
31 15.0
30
25
32 20.0
30
25
EN/SET Serial Interface (S2Cwire™)
The current source output magnitude is controlled
by the EN/SET serial data interface. The interface
records rising edges of the EN/SET pin, and
decodes them into 32 individual current level set-
tings summarized in Table 1. The modulo 32 inter-
face wraps states back to state 1 after the 32nd
clock, so the previous state is achieved by clocking
the EN/SET pin 31 times. The counter can be
clocked at speeds up to 1MHz, so intermediate
states are not visible. The first rising edge of
EN/SET enables the IC and initially sets the output
LED current to 0. Once the final clock cycle is input
for the desired brightness level, the EN/SET pin is
held high to maintain the device output current at
the programmed level. The device is disabled
500µs after the EN/SET pin transitions to a logic
low state. The EN/SET timing is designed to
accommodate a wide range of data rates. After the
first rising edge of EN/SET, the charge pump is
enabled and reaches full capacity after the soft
start time (tSS). During the soft start time, multiple
clock pulses may be entered on the EN/SET pin to
set the final output current level with a single burst
of clocks. Alternatively, the EN/SET clock pulses
may be entered one at a time to gradually increase
the LED brightness over any desired time period. A
constant current is sourced as long as EN/SET
remains in a logic high state. The current source
outputs are switched off after EN/SET has
remained in a low state for at least the tOFF timeout
period.
3132.2004.04.1.0
9
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