AAT3122_05 Datasheet, PDF (1/12 Pages) Advanced Analogic Technologies – High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications

AAT3122
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
General Description
The AAT3122 is a low noise, constant frequency
charge pump DC/DC converter that uses a dual
mode load switch (1X) and fractional (1.5X) con-
version to increase efficiency in white LED applica-
tions. With input voltages ranging from 2.7V to
5.5V, the device can produce an output current of
up to 120mA. A low external parts count (two 1µF
flying capacitors and two small bypass capacitors
at V_IN and OUT) makes the AAT3122 ideally suited
for small battery-powered applications.
AnalogicTech's Simple Serial Control™ (S²Cwire™)
interface is used to enable, disable, and set the
LED drive current with a 32-level logarithmic scale
LED brightness control. The AAT3122 has a ther-
mal management system to protect the device in
the event of a short-circuit condition on any of the
output pins. Built-in soft-start circuitry prevents
excessive inrush current during start-up. High
switching frequency enables the use of small exter-
nal capacitors. A low shutdown current feature dis-
connects the load from V_IN and reduces quiescent
current to less than 1µA. The AAT3122 provides a
single current source output that can be used to
drive up to six LEDs at 20mA each. The AAT3122
is available in a Pb-free TSOPJW-12 package.
Features
ChargePump^™
• V_IN Range: 2.7V to 5.5V
• <1µA of Shutdown Current
• 1 MHz Switching Frequency
• Dual Mode 1X and 1.5X Charge Pump for
Maximum Efficiency
• Only Four External Components
• Simple Serial Control (S²Cwire) Interface
• Low Noise Constant Frequency Operation
• 33% Less Input Current Than Doubler Charge
Pumps
• Small Application Circuit
• Regulated Output Current
• Automatic Soft Start
• No Inductors
• TSOPJW-12 Package
• -40°C to +85°C Temperature Range
Applications
• Programmable Current Source
• White LED Backlighting
Typical Application
V_BATTERY
C_IN
C_OUT
1µF
1µF
EN/SET
V_IN
C1+
AAT3122
V_OUT
C1-
C2+
C2-
EN/SET
D
GND
C1
1µF
C2
1µF
D1
D2
D3
D4
D5
D6
3122.2005.11.1.3
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