AS6591
High Efficiency Synchronous Boost Converter, Fixed 1.2A Flash LED Drivers with PWM Dimming
General Description
The AS6591 is a 3MHz fixed frequency synchronous boost converter, fixed 1.2A flash current output LED driver with PWM dimming function, for distance dimming camera flash LED application and fixed 200mA movie mode applications using high-current white LED in all single cell Li-ion powered products. An adaptive regulation method ensures the current for the LED remains in regulation and maximizes efficiency.
Two simple logic control inputs (ENM and ENF) enable and disable flash and movie mode operation of the AS6591. The movie-mode
For flash mode, a default timer 800mS can be used either to terminate a flash event or as a safety flash timer. The real LED current at flash mode and movie/torch mode can be programmed by external PWM signal at ENM pin.
The AS6591 integrate an intelligent flash current control mode: during flash current turn-on the input voltage falls below the flash mode VIN Monitor threshold, the flash current is stopped at the level that the current ramp had risen to, at the time of the VIN Flash Monitor events.
The AS6591 contain a thermal management system to protect the device; a internal over-voltage protection (OVP) circuitry prevents damaged to the AS6591 from open LED or open circuit conditions; and a cycle-by-cycle current limit prevents damage to the AS6591. Built-in circuitry prevents excessive inrush current during start-up. The shutdown feature reduces quiescent current to less than 1.0μA.
The 3MHz switching frequency allow for the use of tiny, low profile (0.22uH or 0.47uH) inductors and 4.7uF ceramic capacitors. The device is available in 6-pin 2mmX2mm DFN and 10-pin 3mmX3mm DFN packages and is rated over the -40°C to 85°C.
Features
● Input Voltage Range : 2.7V to 5.0V
● No Need External Set Resistors
● Power On Flash Mode Spurious Triggering Suppress
● Up to 3.0MHz Switching Frequency for Smaller Inductor Using
● Output Current Soft-Start
● Optimize Flash Current During Low Battery
● Intelligent Flash Current Control● Drives up to Fixed 1.2A Output Current
● High Efficiency PWM Boost Converter
● Up to 97% Efficiency with Small Inductor
● Under Voltage Lock-Out
● Over-Temperature Protection
● Over Voltage (Open LED) Protection● LED Short Circuit Protection
● Flash Mode and Movie/Torch Mode LED Current can be Programmed via PWM Signal at ENM pin
● PWM Dimming Frequency: 1kHz to 1MHz
● 800mS Flash Timer Control
● Cycle by Cycle Current Limit
● Separate Hardware Flash and Movie Enable
● Internally Set Fixed Flash/Movie Currents Flash Mode Current: 1.2A Movie Mode Current: 0.2A● Small Solution Size
● Less than 1uA Shutdown Current
● RoHS and Green Compliant
● DFN2020-6L and DFN3030-10L Packages
● -40℃ to +85 ℃ Temperature Range
Applications
● Camera Flashes and Movies
● Cell Phones or Smart Phones
● PDAs and Digital Camera
● White LED Biasing
● Mobile Handsets
● Tablet PCs and Laptops / Netbooks
● Camcorder Video Light (Movie Light)
