Flash LED Drivers From Diodes Inc. Deliver High-Current Stability in Portable Devices
September 26, 2019
Diodes Incorporated?s AL3644 high-speed, dual-channel flash LED driver combines flexible switching-frequency capabilities with constant output current.
Diodes Incorporated’s AL3644 high-speed, dual-channel flash LED driver combines flexible switching-frequency capabilities with constant output current to support advanced camera flash and torch functionality in smartphones and portable consumer devices. Key features include independently-controlled output currents configured through an I2C-compatible interface, and the ability to combine two devices (with different device identification addresses) to drive four LEDs up to 6A for quad-channel applications.
The AL3644 employs a constant-frequency, synchronous-boost, current-mode PWM converter to deliver up to 1.5A for each of the two constant current sources across its 2.5V to 5V input voltage range. The I2C-compatible interface, operating at up to 400kHz, is used to configure the device to deliver a constant current at one of 128 levels between 1.4mA and 1.5A. The ratio between the two outputs is also adjustable.
Two switching-frequency options, 2MHz and 4MHz, are provided, and the AL3644 also integrates a comparator that can be used with an external NTC to detect thermal variations. An input voltage monitor ensures the output current remains stable if, for example, the input voltage level drops as the device’s battery supply falls. Fault status bits, interrogated over the I2C-compatible interface, provide a host controller with operational data, such as flash current time-out, LED overtemperature, LED open/short failure, thermal shutdown, and input undervoltage.
The AL3644 and AL3644TT (signifying different device identification addresses) are available in low torch current and high torch current variants in a U-WLB1713-12 package measuring 1.75mm × 1.35mm and priced at $0.30 each in 1,000 piece quantities.
Learn more at www.diodes.com.