AAT3153
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
The six constant current sink inputs (D1 to D6) can
drive six individual LEDs with a maximum current
of 20mA each. The unused sink inputs must be
connected to V
OUT
, otherwise the part will operate
only in 2X charge pump mode. The S
2
Cwire serial
interface enables the AAT3153 and sets the current
sink magnitudes. S
2
Cwire addressing allows inde-
pendent control of two groups of current sink input:
D1-D4 and D5-D6.
The S
2
Cwire serial interface has flexible timing.
Data can be clocked-in at speeds greater than
1MHz, or much slower, such as 15kHz. After data
is submitted, EN/SET is held high to latch the data.
Once EN/SET has been held in the logic high state
for time T
LAT
, the programmed current becomes
active and the internal data register is reset to zero.
For subsequent current level programming, the
number of rising edges corresponding to the
desired code must be entered on the EN/SET pin.
When EN/SET is held low for an amount of time
greater than T
OFF
, the AAT3153 enters into shutdown
mode and draws less than 1µA from V
IN
. The inter-
nal data register is reset to zero during shutdown.
Main Group
(D1-D4)
I
OUT
(mA)
20
14
10
7
20
14
10
7
0
0
0
0
0.05
0.5
1
2
Constant Current Output Level Settings
The constant current sink levels for D1 to D6 are
set via the serial interface. No PWM (pulse width
modulation) or additional control circuitry are need-
ed to control LED brightness. This feature greatly
reduces the burden on a microcontroller or system
IC to manage LED or display brightness, allowing
the user to "set it and forget it." With its high-speed
serial interface (up to 1MHz data rate), the input
sink current of the AAT3153 can be changed suc-
cessively to brighten or dim LEDs, giving the users
real-time control of LED brightness. Because the
inputs D1 to D6 are true independent constant cur-
rent sinks, the voltage observed on any single
given input will be determined by the actual forward
voltage (V
F
) for the LED being driven.
Data
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Sub Group
(D5-D6)
I
OUT
(mA)
20
14
10
7
0
0
0
0
20
14
10
7
0.05
0.5
1
2
S
2
Cwire Serial Interface
The current sink input magnitude on the AAT3153 is
controlled by AnalogicTech's S
2
Cwire serial inter-
face. The interface records rising edges of the
EN/SET pin and decodes them into 16 different
states, as indicated in Table 1. There are four bright-
ness levels for the main or sub-display group with
the possibility of individually turning ON or OFF
each group. To further optimize power efficiency,
the AAT3153 also offers four low-current levels for
dim LED operation (Data 13 through 16). During
this low-current mode, the internal supply current
reduces to only 50µA typical.
Table 1: AAT3153 Current Settings.
3153.2005.12.0.93
9
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
