AW3643CSR datasheet(16/39 Pages) AWINIC

16 / 39 page

AW3643

Jan 2018 V1.4

www.awinic.com.cn

DETAILED FUNCTIONAL DESCRIPTION

The AW3643 is a high-power white LED flash driver capable of delivering up to 1.5A in either of the two

parallel LEDs. The total allowed LED current during operation is 1.5A (ILED1+ILED2≤1.5A). The device

incorporates a 2MHz or 4MHz constant frequency-synchronous current-mode PWM boost converter and dual

high-side current sources to regulate the LED current over the 2.7V to 5.5V input voltage range.

The AW3643 PWM DC-DC boost converter switches and boosts the output to maintain at least VHR across

each of the current sources (LED1/2). This minimum headroom voltage ensures that both current sources

remain in regulation. If the input voltage is above the LED voltage + current source headroom voltage, the

device would not switch, but turns the PMOS on continuously (Pass mode). In Pass mode the difference

between (VIN

− ILED ×RPMOS) and the voltage across the LED is dropped across the current source.

The AW3643 has three logic inputs including a hardware Flash Enable (STROBE), a hardware Torch Enable

(TORCH/TEMP, TORCH = default), and a Flash Interrupt input (TX) designed to interrupt the flash pulse

during high battery-current conditions. These logic inputs have internal 300

kΩ (typical) pull-down resistors to

GND.

Additional features of the AW3643 include an internal comparator for LED thermal sensing via an external

NTC thermistor and an input voltage monitor that can reduce the Flash current during low VIN conditions. It

also has a Hardware Enable (HWEN) pin that can be used to reset the state of the device and the registers by

pulling the HWEN pin to ground.

Control is done via an I2C-compatible interface. This includes adjustment of the Flash and Torch current

levels, changing the Flash Timeout Duration, and changing the switch current limit. Additionally, there are flag

and status bits that indicate flash current timeout, LED over-temperature condition, LED failure (open/short),

device thermal shutdown, TX interrupt, and VIN under-voltage conditions.

AW3643CSR Datasheet(PDF) 16 Page - Shanghai awinic technology co.,ltd