AAT3157

High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications

Please note: this product is being discontinued and is not recommended for new designs.

The AAT3157 is a low noise, constant frequency charge pump DC/DC converter that uses a tri-mode load switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency for white LED applications. The AAT3157 is capable of driving up to three channels of LEDs at 20mA 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 VIN and VOUT) make this part ideally suited for small battery-powered applications.

AnalogicTech's S²Cwire™ (Simple Serial Control™) serial digital input is used to enable, disable, and set current for each LED with 16 settings down to 50µA. The low-current mode supply current can be as low as 50µA to save power. Each output of the AAT3157 is equipped with built-in protection for VOUT short-circuit and auto-disable for load short-circuit conditions. Built-in soft-start circuitry prevents excessive inrush current during start-up. A low-current shutdown feature disconnects the load from VIN and reduces quiescent current to less than 1µA.

The AAT3157 is available in a Pb-free, space-saving, 2.85x3.0mm 12-pin TSOPJW package.

Please note: AAT3157 is not recommended for new designs.

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Specifications

Number of LEDs3
LED Channels3
LED(s) per/Ch1
Min. VIN (V)2.7
Max. VIN (V)5.5
InterfaceS2Cwire™
Typ. IQ (μA)50
Peak Efficiency97%
Current Accuracy (%)±10%
Current Matching (%)±0.5%
Max. IOUT per/Ch (mA)20
PackageTSOPJW, 12L
Package (mm)3 x 2.85 x 1.02
PackageTSOPJW-12

Features

  • VIN Range: 2.7V to 5.5V
  • Fully Programmable Current with Single Wire
  • 16 Current Levels
  • Four Low Current Settings Down to 50µA
  • Low IQ (50µA) for Low Current Mode
  • Tri-Mode 1X, 1.5X, and 2X Charge Pump for Maximum Efficiency and VF Coverage
  • Drives up to Three Channels of LEDs
  • No Inductors, Low Noise Operation
  • 1MHz Constant Switching Frequency
  • Small Application Circuit
  • Built-In Thermal Protection
  • Automatic Soft Start
  • IQ < 1µA in Shutdown
  • 2.85x3.0mm TSOPJW-12 Package

Product Documents

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