General
Description
The AS6585B is a 3MHz fixed frequency synchronous boost converter, optimized for 0.75A/ch, total 1.5A flash current output LED driver with PWM dimming function, for distance dimming camera flash LED application and maximum 800mA movie mode applications using high-current white LEDs in all single cell Li-ion powered products. An adaptive regulation method ensures the current for each 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 AS6585B. The movie-mode and flash-mode current levels are independently fixed by two separate resistors (RSETM
and RSETF).
For flash mode, a default timer 800mS can be used either to terminate a flash event or as a safety flash timer. One or two LEDs can be connected to the AS6585B; in
the case of two LEDs the
output current is matched between each diode. The real LED current at flash
mode and movie/torch mode can be programmed by external PWM
signal at ENM pin.
The AS6585B 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 AS6585B contain a thermal management system to protect the device; a internal over-voltage protection (OVP) circuitry prevents damaged to the AS6585B from open LED or open circuit conditions; and a cycle-by-cycle current limit prevents damage to the AS6585B. 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 (0.47uH or 1.0uH) inductors and 4.7uF ceramic capacitors. The device is available in 14-pin 2mmX3mm DFN package and is rated over the -40°C to
85°C.
Features
● Input Voltage Range : 2.7V to 5.0V
● Power On Flash Mode Spurious Triggering Suppress
● Up to 3.0MHz Switching Frequency for Smaller Inductor Using
● Drives up to 1.5A Output Current (0.75A per Channel)
● 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
● Separate Hardware Flash and Movie Enable
● Set Flash/Movie Currents Flash Mode Current: 0.75A/Ch Movie Mode Current: 0.40A/Ch
● 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 1.5A Output Current (0.75A per Channel)
● 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
● Flash Mode PWM Dimming Frequency: 1kHz to 200KHz
● 800mS Flash Timer Control
● Cycle by Cycle Current Limit● Separate Hardware Flash and Movie Enable
● Set Flash/Movie Currents Flash Mode Current: 0.75A/Ch Movie Mode Current: 0.40A/Ch
● Two Resistors Set Flash and Movie Current Independently
● 14- pin, 2mm X 3mm DFN Packages
● -40℃ to +85 ℃ Temperature Range
● Small Solution Size
● Less than 1uA Shutdown Current
● RoHS and Green Compliant● 14- pin, 2mm X 3mm DFN Packages
● -40℃ to +85 ℃ Temperature Range
Applications
● Camera Flashes and Movies
● Cell Phones or Smart Phones
● PDAs and Digital Camera
● White LED Biasing
● Mobil Handsets
● Tablet PCs and Laptops/Netbooks● Camcorder Video Light (Movie Light)
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