Digital pots offer alternative to DACs

Catalyst Semiconductor Inc. has added five new 32-tap devices to its extensive family of over 30 digitally programmable potentiometers (DPP). The CAT5123, CAT5124 and CAT5125 are volatile devices, while the CAT5127 and CAT5129 offer non-volatile wiper storage. All of these new devices feature a user-friendly up/down control interface.

The CAT5127 is said to be the world's smallest digital potentiometer in an 8-lead, 2-by-2.5mm, TDFN package. It is also available in an 8-lead MSOP package. Both packages are pin-for-pin replacements for Intersil's X93154.

The CAT5129 comes in a 6-lead SOT23 package and is a pin-for-pin replacement for Maxim's MAX5471 digital potentiometer. The CAT5123, CAT5124 and CAT5125 are available in SOT23 packages and offer pin-for-pin replacements for Maxim's MAX5466, MAX5467 and MAX5468 devices.

Miniature pots
With their small size, these new MiniPot digital potentiometers are suitable for LCD screen adjustment; automated calibration; contrast, brightness and volume control; gain adjustment; line impedance matching and mechanical potentiometer replacement in handheld and other space-constrained applications.

All five DPPs offer low-noise, stable and reliable alternatives to DACs and mechanical potentiometers. The CAT5127 and CAT5129 feature on-chip, non-volatile EEPROM memory, which allows designers to calibrate once and retain the setting in memory, even if power is lost. The wiper position can be preset to any position on the device and, on power-up, the wiper will go to the preset position, which is stored in the on-chip EEPROM. The CAT5123, CAT5124 and CAT5125 are volatile devices where the wiper powers on at the midscale setting. DAC-based approaches typically require external memory and additional interconnects resulting in added board real estate and system costs.

Shock-, vibration-proof
Additionally, since these DPPs are silicon-based, they are insensitive to mechanical vibrations, shock and oxidation, making them higher reliability alternatives to mechanical potentiometers across most environmental conditions, the company said.

All these DPPs are priced at 43 cents in 10,000 piece quantities, except for the CAT5127 TDFN package, which is 53 cents. Samples are available today. Projected lead-time for production quantities is currently 10 weeks ARO.