AAT3194 Datasheet, PDF (1/14 Pages) Advanced Analogic Technologies – High Efficiency 1.5X Fractional Charge Pump For White LED Applications

AAT3194
High Efficiency 1.5X Fractional Charge
Pump For White LED Applications
General Description
Features
ChargePump^™
The AAT3194 is a low noise, constant frequency
charge pump DC/DC converters that use fractional
(1.5X) conversion to increase efficiency in white
LED applications. The devices can be used to pro-
duce current levels up to 20mA for each output
from a 2.7V to 5.5V input. A low external parts
count (two 1µF flying capacitors and two small
bypass capacitors at IN and OUT) makes these
devices 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 for 32-level logarithmic scale LED
brightness control. The AAT3194 has a thermal
management system for protection 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. A high switching frequency
enables the use of small external capacitors. A low-
current shutdown feature disconnects the load from
V_IN and reduces quiescent current to less than 1µA.
The AAT3194 is available in a Pb-free 12-pin
TSOPJW package.
• V_IN Range: 2.7V to 5.5V
• 20mA Full-Scale Current
• Simple Serial Control (S²Cwire) Interface
— 32-Position Logarithmic Scale with Digital
Control
• Low Noise Constant Frequency Operation
• 33% Less Input Current Than Doubler
Charge Pump
• High Accuracy Brightness Matching
• Small Application Circuit
• Regulated Output Current
• Automatic Soft Start
• No Inductors
• 600kHz Switching Frequency
• I_Q <1µA in Shutdown
• Temperature Range: -40°C to 85°C
• 12-Pin TSOPJW Package
Applications
• Programmable Current Source
• White LED Backlighting
Typical Application
V_BATTERY
C_IN
C_OUT
1µF
1µF
IN
C1+
C1
1µF
OUT
C1-
C2+
AAT3194
C2
1µF
C2-
EN/SET
D1
D2
D3
EN/SET
D4
GND
D4
D3
D2
D1
3194.2006.09.1.0
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