Charge pump powers up backlights and flashes

The AAT2801 high efficiency charge pump supports both white LED backlight and white LED camera flash applications for portable systems powered by lithium-ion/polymer batteries.

AnalogicTech has introduced its first multifunction charge pump device.

The AAT2801 high efficiency charge pump supports both white LED backlight and white LED camera flash applications for portable systems powered by lithium-ion/polymer batteries.

Driving up to four LEDs and delivering up to 30mA on each current source output, the device offers significant space savings to OEMs building mobile phones, smart phones, and PDAs.

As the first device in AnalogicTech's family of multifunction power management chips, the AAT2801 charge pump allows the company to address today's complex portable applications with a single, 4 x 4mm, low-power solution.

By integrating white LED backlight and camera flash technologies into a single, 16-pin TDFN44 package, the device allows OEMs to support two important lighting functions while reducing the board space by more than 30%.

The backlight charge pump in the AAT2801 produces current levels up to 30mA on each of its four current mode outputs.

To maximise power efficiency, the charge pump operates in 1x, 1.5x, and 2x modes.

AnalogicTech's AutoBias technology allows the device to automatically select the appropriate voltage rail for each LED by comparing the forward voltage with the input voltage.

A single wire simple serial control (S2Cwire) digital interface is used to control LED drive current with a 32-level logarithmic brightness scale.

For flash applications, the AAT2801 integrates a charge pump with a regulated output voltage.

Delivering up to 120mA of continuous current for "movie-mode" or up to 300mA of pulsed current for camera flash, the circuit adds an independent enable pin to maximise power savings.

A built-in thermal management circuit protects the device from fault conditions.

Soft-start circuitry prevents excessive inrush current during startup.

The AAT2801's high 1MHz charge pump switching frequency allows designers to support the device with extremely small ceramic capacitors.

Specified over the -40 to +85C temperature range, the AAT2801 is available now in a lead-free 16-pin TDFN44 package.

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