Sunnyvale, Calif.—Advanced Analogic Technologies' AAT2820 is a triple-output charge pump regulator specifically suited to powering TFT LCDs and CCD image sensors in handheld products with lithium-ion/polymer batteries. The chip generates three regulated output voltages from two charge pumps for turn-on gate drive bias (Vpos), turn-off gate voltage bias (Vneg), and logic.
"An increasing number of smartphones, PDAs, and other portable devices now integrate CCD camera chips and TFT displays which need positive and negative low-current bias supplies," said Erik Ogren, product marketing manager. "By providing two regulated output voltages up to +25 volts and -25 volts and a third regulated output voltage for logic—all without the use of an inductor—the AAT2820 offers battery-powered device designers an extremely compact, low-profile solution for power regulation."
The main power output is a charge pump doubler that provides 5 volts at up to 150 mA for display logic. It also provides the operating voltage for the second charge pump, which in a single stage delivers independently regulated positive and negative voltages. External diode and capacitor multiplier stages regulate the outputs to ±25 volts for the display. No inductors are required. Operating at 1 MHz, the AAT2820 uses small external capacitors, which facilitate a low-profile design only 0.8 mm high.
Integrated soft-start circuitry protects the device against excessive inrush current during startup. A low- power shutdown feature disconnects the load from the input supply voltage and reduces quiescent current to less than 0.1 microamp. A thermal protection circuit shuts down the charge pumps if the die temperature rises above a preset internal thermal limit.
The datasheet is available at www.analogictech.com/products/digitalfiles/AAT2820.pdf. The AAT2820, available in a Pb-free TDFN44-16 package, is priced at $1.53 each in 1k quantities.
Advanced Analogic Technologies, 1-408-737-4600, www.analogictech.com