AS3644 datasheet(2/24 Pages) AMSCO

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AS3644

Ultra Small Low Cost 320mA Inductive White LED Flash Driver

www.austriamicrosystems.com/AS3644

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Datasheet

1 General Description

The AS3644 is an inductive high efficient DCDC step up

converter driving a current source. The DCDC step up

converter operates at a fixed frequency of 4MHz and

includes soft startup to allow easy integration into noise

sensitive RF systems. The current source operates in

flash/torch/assist (video/autofocus) mode.

The AS3644 includes flash timer, overvoltage, overtem-

perature, 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 compo-

nents and allowing in-circuit test. This reduces test time

and simplifies production test procedures.

The AS3644 is controlled by an I

2C interface to allow

sophisticated control of all settings like currents and tim-

ings.

The complete flash driver solution measures only

11mm

2 PCB area.

The AS3644 is available in a space-saving WL-CSP

package measuring only 1.5x1.1x0.6mm and operates

over the -30ºC to +85ºC temperature range.

Figure 1. Typical Operating Circuit

2 Key Features



Total flash driver solution only 11mm



High efficiency 4MHz fixed frequency DCDC Boost

converter with soft start allows small coils



LED currents

260mA to 320mA flash current (20mA steps)

51.6mA or 72.3mA Assist light (=torch) current



Flash LED(s) cathode connected to ground:

Improved thermal performance (ground = heat sink)

Simplified PCB layout



Adjustable Flash Timer

30ms to 480ms in 30ms steps



Flash, Torch, Assist and Indicator Mode



Protection functions:

Automatic Flash timer to protect the LED

Overvoltage and undervoltage Protection

Overtemperature Protection

LED short circuit protection



Available in tiny WL-CSP Packages

2x3 balls 0.5mm pitch, 1.5x1.1x0.6mm package size

3 Applications

Flash/Torch for mobile phones, digital cameras and PDA

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