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Diodes Corporation’s Flash LED Drivers Provide Stable High Current for Portable Devices in Dual and Quad Channel Applications

[October172019PlanoTX]Diodes Incorporated (Nasdaq: DIOD) today announced the AL3644, a high-speed dual-channel flash LED driver designed to support advanced camera flash and torch functions. on the latest smartphones and other portable consumer devices. Key features include independently controllable output currents that can be set via an I2C-compatible interface, and the ability to combine two devices (each with a different device identification address) to drive four LEDs for up to 6A in four-channel applications. The AL3644 is offered in a chip-scale package and combines flexible frequency switching with constant output current.

The AL3644 uses a constant frequency, synchronous boost current mode PWM converter capable of delivering up to 1.5A each from two constant current sources over an input voltage range of 2.5V to 5V. The driver uses an I2C compatible interface with a maximum operating frequency of 400kHz. The device can be set to provide constant current at any of 128 segments between 1.4mA and 1.5A. The ratio of the two outputs can also be adjusted through the I2C compatible interface.

As the boom in portable and wearable devices continues, which require sophisticated camera functions (including video recording), as well as convenient flashlight functions, the demand for highly flexible LED drivers continues to increase. The AL3644 provides dual-channel parallel current sources, and the efficiency of both torch mode and flash mode exceeds 85%, which just meets this requirement.

The device offers two frequency switching options of 2MHz and 4MHz, allowing engineers to gain more design flexibility and simplify the overall design. Higher switching frequencies make it easier to use small form factor passive components such as low profile inductors and small 10µF ceramic capacitors, reducing the overall bill of materials.

AL3644 is the first LED driver with I2C compatible interface introduced by Diodes Company. It also integrates a comparator, which can be used with an external NTC to detect thermal changes. An input voltage monitor ensures that the output current remains stable for situations such as the input voltage drop as the device’s battery supply decreases. Fault status bits, queried via an I2C-compatible interface, provide the host controller with various operational data such as flash current timeout, LED overheat, LED open/short fault, overtemperature shutdown, and input undervoltage.

The AL3644 and AL3644TT (representing different device identification addresses) are available in low-torch-current and high-torch-current versions in a U-WLB1713-12 package measuring 1.75mm × 1.35mm.

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