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Tiny DC/DC converter powers up to seven WLEDs

Posted: 18 Jul 2007 ?? ?Print Version ?Bookmark and Share

Keywords:charge pump DC/DC converter? multidisplay handheld devices? white LEDs?

Texas Instruments Inc. has introduced a high-efficiency, constant-frequency charge pump DC/DC converter that uses dual-mode conversion to maximize efficiency over the 3-6V input voltage range. The TPS60250 device provides a fully programmable current with an I?C interface for portable applications such as cellphones, PDAs and multidisplay handheld devices.

The TPS60250 charge pump, housed in a 16-pin QFN package (3mm x 3 mm), drives up to five white LEDs for a main display and up to two white LEDs for a subdisplay with regulated constant current for uniform intensity. By using adaptive 1x/1.5x charge pump modes and very low-dropout current regulators, TPS60250 achieves high efficiency over the full one-cell lithium-battery input voltage range. The device also provides auto-switching between 1x and 1.5x mode for maximum efficiency.

Four enable inputs, available through I?C, are used for simple on/off controls for the independent displays. To lower operating current when using one subdisplay LED, TPS60250 provides completely separate operation in subdisplay LEDs. The device features 2 percent current matching for sub-LEDs at light load condition (each 100?A).

TPS60250 provides 64 dimming steps with 25mA maximum (sub- and main display banks) and four dimming steps with 80mA maximum (DM5 for auxiliary application). Other features include a 750kHz charge pump frequency, continuous 230mA maximum output current, built-in soft start and current limit and open lamp detection.

TPS60250 is shipping in volume production now. Pricing starts at $1.40 in 1,000-unit quantities.

- Gina Roos
eeProductCenter




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