High Efficiency 1X/1.5X/2X Charge Pump for
Six-Channel White LED Applications
General Description
The AAT3164 is a low noise, constant frequency
charge pump DC/DC converter that uses a tri-
mode load switch (1X), fractional (1.5X), and dou-
bling (2X) conversion to maximize efficiency for
white LED applications. The device is capable of
driving up to six channels of LEDs at up to 30mA
per channel from a 2.7V to 5.5V input. The current
sinks may be operated individually or in parallel for
driving higher-current LEDs. A low external parts
count (two 1µF flying capacitors and two small 1µF
capacitors at IN and OUT) makes this part ideally
suited for small, battery-powered applications.
AnalogicTech's patented single-wire Simple Serial
Control™ (S
2
Cwire™) serial digital input is used to
enable, disable, and set current for each LED with
16 levels from a maximum of 40mA down to 50µA.
The maximum current level is programmed via an
external resistor. To save power, the low-current
mode supply current can be programmed as low
as 70µA.
Each output of the AAT3164 is equipped with built-
in protection for V
OUT
short-circuit and auto-disable
for LED short-circuit conditions. Built-in soft-start
circuitry prevents excessive inrush current during
start-up. A low-current shutdown feature discon-
nects the load from V
IN
and reduces quiescent cur-
rent to less than 1µA.
The AAT3164 is available in a Pb-free, space-saving,
ultra-thin (3x4x0.75mm), thermally-enhanced 16-pin
TDFN package.
AAT3164
Features
•
•
ChargePump
™
•
•
•
•
•
•
•
•
V
IN
Range: 2.7V to 5.5V
Tri-Mode (1X/1.5X/2X) Charge Pump Operation
— Maximizes Efficiency and LED V
F
Coverage
— 1MHz Constant Switching Frequency
— No Inductors, Low Noise Operation
Drives Six Channels of LEDs up to 30mA/
Channel
— User-Programmable R
SET
Sets Maximum
LED Current
— Excellent LED Channel-to-Channel
Current Match
Digitally Programmable LED Current with
Single-Wire S
2
Cwire Interface
— 16 Current Levels From I
LED_MAX
to 50µA
Low I
Q
(70µA) for Low Current Mode Operation
True Load Disconnect in Shutdown; I
Q
< 1µA
Built-In Thermal Protection
Built-In Auto-Disable for Open LED Circuit
Automatic Soft-Start Minimizes Inrush Startup
Current
Small 3x4mm TDFN34-16 Package
Applications
•
•
•
•
Color (RGB) Lighting
Programmable Current Sinks
White LED Backlighting
White Photo Flash for Digital Still Cameras
Typical Application
1µF
1µF
C1+
IN
Li-Ion
Battery
V
NOM
= 3.6V
C
IN
1
µF
C1- C2+
C2-
OUT
AAT3164
C
OUT
1
µF
D1
D2
D3
D4
D5
D6
OSRAM
LW M67C
GND
D1
D2
D3
D4
D5
D6
EN/SET
EN/SET
RSET
26.1K
1%
3164.2006.07.1.0
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
