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Low-tolerance DCP can be used as variable resistor

Posted: 30 Jun 2009     Print Version  Bookmark and Share

Keywords:digipot  potentiometer  resistor 

ISL22317 DCP

The first low-voltage DCP with <1 per cent typical resistor tolerance has been launched by Intersil Corp. The ISL22317 has ultralow tolerance that is can be used as a true variable resistor. Thus users can set standard and non-standard resistor values for open-loop applications.

The ISL22317 is useful for designs that need specific current and resistor values, including test and measurement circuits, medical devices, backlight controls, and analogue devoices that need adjusting for specific resistances. The patent-pending architecture of the ISL22317 allows it to track an external resistor within 10ppm/°C, improving overall system accuracy for temperatures up to 125°C.

With this DCP users can select accurate pre-determined resistor values, and use calculated resistor values in schematics, reducing programming time and development costs. It also allows the use of the known value of one system to calibrate other systems. The device employs an easy-to-use I2C interface to program accurate resistor settings >10 lakh times in the integrated EEPROM memory.

The ISL22317 features a zero-compensated wiper resistance in rheostat mode. Overall accuracy is improved by negating wiper resistance, especially at the low tap positions where the ratio of wiper resistance to actual resistance is much higher. So the users can perform schematic calculations based on an actual 1 per cent value. This is an improvement over competitive solutions that have >±20 per cent tolerance of the resistor string in addition to wiper resistance error.

The product also features 128-tap positions, I2C serial interface and pin selectable slave address. The digipot also offers 10-, 50- and 100kΩ total resistance options, monotonic over-temperature and non-volatile EEPROM storage of wiper position. In addition, the device packs single 2.7V to 5.5V supply and -40°C to 125°C operating temperature range.

The ISL22317 DCP is available in 3mm x 3mm TDFN Package with 0.75mm max thickness and 0.65mm pitch. Pricing is Rs.88.18 ($1.80) for 1,000 units.

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