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03 November, 2008 16:11 print this article email this article to a friend

4-channel LED drivers reduce component count by 25%, saving space in entry-level cell phones

AnalogicTech has introduced the AAT3104 and AAT3195, two 4-channel, charge pump-based LED drivers for larger LCD screens in reduced feature set cell phones and portable systems. Available in compact 2 x 2.1mm packages, the devices offer designers 16-step, 32-step or PWM current control in a space-saving footprint.  By using an efficient charge pump with 1x and 2x modes, the AAT3104 and AAT3195 drivers reduce the external component count by 25% over competing solutions.

To deliver uniform brightness and excellent matching between adjacent LEDs, the AAT3104 provides common current sinks for command anode configurations, while the AAT3195 supports common sources for common cathode configurations.

As engineers add new functionality to entry-level cell phones and other portable systems, they often integrate larger displays into their designs.  By providing the required compliance voltage to forward bias the LED as well as a means to control and set the desired current for both common anode and common cathode configurations with four LEDs, these additions to AnalogicTech's extensive LED driver product portfolio offer portable system designers improved design flexibility, high power efficiency, lower component count, and multiple current control options in a space-saving package.

The AAT3104 is a current-source LED driver capable of driving up to four LEDs at up to 30mA each. The charge pump-based device automatically switches between a 1x and 2x mode to maximize efficiency and optimize LED current accuracy and matching.  LED output current accuracy is +/-10%.  LED output current matching is +/-3%.

The device operates at a 1MHz switching frequency and comes in two versions that offer either 16-step (AAT3104-1) or 32-step (AAT3104-2) control of LED brightness via AnalogicTech's patented single-wire S2Cwire interface.  A PWM version, the AAT3105, will be available shortly.

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