National Semiconductor Debuts the LM2622 Step-Up Converter

National Semiconductor Corp. (Santa Clara, CA) has released a step-up dc/dc converter optimized for powering large-format liquid crystal panels found in notebook PCs. The LM2622, which typically resides inside the panel, is designed to boost a single low-voltage supply from the PC's mother-board to one or more high-voltage, high-power supplies required by the panel's row and column drivers. The LM2622 may also be used for biasing small-format liquid crystal displays found, for example, in cellular phones, digital cameras and other hand-held portable information appliances.

Packaged in a tiny MSOP-8, the LM2622's power switch has an Rds(on) of 150mOhms at 3V(in) and 1.2A, I(ds). It switches at either 600kHz or 1.3MHz, enabling the use of small, thin inductors. Its control loop can be compensated for a specific application, allowing some flexibility in the selection of an inductor and enabling the use of low-ESR ceramic chip capacitors as output capacitors.

Supply voltage range is 2V to 12V and output voltage is adjustable up to 17.5V. The switch voltage limit is 18V and the switch current limit is 1A minimum. Current-mode, fixed-frequency PWM operation minimizes interference in noise-sensitive applications and safety features include current limiting and thermal shutdown.

The LM2622 is available now starting at $1.95 each in quantities of 1,000, and housed in a low-profile, eight-pin MSOP package.