AAT3159 Datasheet, PDF (9/15 Pages) Advanced Analogic Technologies – High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications

ChargePump^TM
PRODUCT DATASHEET
AAT3159
High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications
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
(1MHz data rate), the LED current can be changed suc-
cessively to brighten or dim LEDs in smooth transitions
(e.g., to fade-out) or in abrupt steps, giving the user
complete programmability and real-time control of LED
brightness. The code settings for the AAT3159 are listed
in Table 1.
S²Cwire Serial Interface
The current level magnitude is controlled by AnalogicTech’s
Simple Serial Control (S²Cwire) serial interface. The
interface records rising edges of the EN/SET pin and
decodes them into 16 different states. The 16 current
level settings available are indicated in Table 1.
Data
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
All LED Outputs D1 - D4
100%
90%
79%
70%
62%
55%
48%
40%
31%
21%
15%
11%
1mA
500μA
100μA
50μA
Table 1: AAT3159 LED Current Levels as a
Percentage of the Maximum Level Set by R_SET.
The S²Cwire 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 longer than T_LAT (500μs), the pro-
grammed current becomes active. For subsequent cur-
rent level programming, the number of rising edges cor-
responding to the desired code must be entered on the
EN/SET pin.
When EN/SET is held logic low longer than T_OFF (500μs),
the AAT3159 enters into shutdown mode and draws less
than 1μA from IN. The internal data register is reset to
zero during shutdown.
Auto-Disable Feature
The AAT3159 is equipped with an auto-disable feature
for each LED channel. After the IC is enabled and started
up, a test current of 100μA (typical) is forced through
each sink channel. The channel will be disabled if the
voltage of that particular current sink (DX pin) does not
drop to a specific threshold. This feature is very conve-
nient for disabling an unused channel or during an LED
fail short event.
Thermal Protection
The AAT3159 has built-in thermal protection circuit that
will shut down the charge pump if the die temperature
rises above the thermal limit, as is the case during a
short-circuit event with the OUT pin.
S²Cwire Serial Interface Timing
EN/SET
Data Reg
T _HI
T _LO
T_LAT
1
2
n
n <= 16
1
T_OFF
n
0
3159.2007.10.1.0
www.analogictech.com
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