Description

The AS3644 is an inductive high efficient DCDC step-up converter driving one current source. It operates at a fixed frequency of 4MHz and includes a soft startup to allow easy integration into noise sensitive RF systems. The current source operates in flash/torch/assist (video/autofocus) and indicator mode.

The AS3644 includes flash timer, overvoltage, overtemperature, undervoltage and LED short circuit protection functions.

The AS3644 is able to detect a broken coil. Together with the LED short and open detection the AS3644 can be used to verify the connection to its external components and allowing in-circuit test. This reduces test time and simplifies production test procedures.

The AS3644 is controlled by an I2C interface and allows change of all settings like currents and timings for best adaption to the used camera system.

The complete flash driver solution measures only 11mm2 PCB area.

The AS3644 is available in a space-saving WL-CSP package (1.5x1.1x0.6mm) and operates over the -30ºC to +85ºC temperature range.

Key Features

• Solution size only 11mm2 allow space and cost saving designs
• High efficiency 4MHz fixed frequency DCDC boost converter with soft start allows small coils
• Different adjustable LED current modes
  • Flash, Torch, Assist and Indicator Mode
  • Up to 320mA flash & torch current (10mA steps)
  • 1.6mA,3.2mA,4.8mA or 6.5mA indicator light current (51.6mA with 1...4/32 duty cycle)
• Adjustable flash timer
  • 30ms to 480ms in 30ms steps
• Build-in protection functions
  • Automatic fash timer to protect the LED
  • Overvoltage protection
  • Undervoltage lockout
  • Overtemperature protection
  • LED short circuit protection
• Available in tiny WL-CSP package
  • 2x3 balls
  • 0.5mm pitch
  • 1.5x1.1x0.6mm

Applications

• Flash/Torch for mobile phones
• Digital cameras
• PDAs
• Medical skin cameras
• Assist light / reading lamp handheld devices