Digital pot’s high-voltage interface optimizes LCD performance

Sunnyvale, Calif.&#8212Catalyst Semiconductor's CAT1533 touts several advantages over competing linear digital potentiometer controller products as well as traditional mechanical pots. As one example, the 128-tap, 7-bit device delivers a high-voltage output (up to 15 volts) that can be adjusted to optimize the screen settings for a liquid crystal display (LCD). The chip also includes non-volatile memory storage for one-time programming of wiper settings to provide automatic recall of saved settings at power-up.

Operationally, the device provides separate power inputs for the control logic and address decoder and memory (Vcc of 2.7 to 5.5 volts), and the V+ input (up to 15 volts) for the analog source powering the chip's 128-tap position decode control circuitry. This scheme provides high voltage at lower noise than using an internal charge pump. In addition, apart from the company's first device (CAT5132) to address Vcom adjustment using an I2 C interface, the CAT5133 offers an increment/decrement interface.

The CAT5133's non-volatile, EEPROM memory allows designers to calibrate once, and the setting is retained even if power is lost. The wiper can be preset to any position. In contrast, DAC-based approaches typically require external memory and additional interconnects.
In addition, the silicon-based CAT5133 is insensitive to mechanical vibrations, shock and oxidation.

Click here for the product datasheet. The CAT5133, in a RoHS-compliant, environment friendly “green” 10-pin MSOP package, is priced at 88 cents in 1k quantities. Samples and evaluation kits are available now. Projected lead-times for production quantities are currently 6 to 8 weeks ARO.

Catalyst Semiconductor , 1-408)-542-1000,

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