AAT1277

1.5A Step-Up Current Regulator for Flash LEDs


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

The AAT1277 is a high-efficiency, high-current boost converter capable of 1.5A typical output current. It is an ideal power solution for LED photo flash applications in all single cell Li-ion powered products.

The AAT1277 maintains output current regulation by switching the internal high-side and low-side switch transistors. The transistor switches are pulse-width modulated at a fixed frequency of 2MHz. The high switching frequency allows the use of a small inductor and output capacitor, making the AAT1277 ideally suited for small battery-powered applications.

Three simple logic control inputs enable and disable flash and movie mode operation of the AAT1277. Movie-mode and Flash-mode current levels are independently fixed by two separate resistors. For Flash mode, a default timer can be used either to terminate a flash event or as a safety feature. Also included is a Flash Inhibit pin which reduces the flash current to movie-mode levels during high battery demand. One or two LEDs can be connected to the AAT1277; in the case of two LEDs the output current is matched between each diode.

The AAT1277 contains a thermal management system to protect the device in the event of an output short-circuit condition. Built-in circuitry prevents excessive inrush current during start-up. The shutdown feature reduces quiescent current to less than 1.0μA.

The AAT1277 is available in a 18 ball 1.5mm x 2.4mm CSP package.

Specifications

Flash IOUT Total (mA)1500
Movie Mode IOUT Total (mA)100
LED Channels2
Min. VIN (V)2.7
Max. VIN (V)5.5
Max. VOUT (V)5.5
InterfaceEnable
Max. Shutdown Current (μA)1
Typ. IQ (μA)230
Peak Efficiency85%
Package
Package (mm)
PackageWLCSP-18

Features

  • VIN Range: 2.7V to 5.5V
  • Dual Channel Output
  • Up to 1.5A Regulated Output Current (750mA per channel)
  • Up to 85% Efficiency with Small Inductor (1μH)
  • 2 MHz Switching Frequency
  • Separate Flash/Movie Mode Enable
  • Separate Flash Inhibit
  • User-Programmable Safety Timer
  • Two Resistors Set Flash and Movie Mode Current Independently
  • True Load Disconnect
  • Bypass Mode Input Current Limit 1.9A (typ.)
  • Over-Voltage (Open LED, Open Circuit) Protection
  • Short Circuit Protection
  • Over-Temperature Protection
  • Shutdown Current < 1.0μA
  • 18 Ball 1.5mm x 2.4mm CSP Package
  • -40°C to +85°C Operating Temperature Range

Product Documents