Electronic Design

Voltage Reference Yields 1-mV Precision From 12-Bit ADCs

Speaking of new approaches to familiar products, bandgap voltage references have been around since the mid-1970s. Buried-zener references have been around since the early 1980s. Now Intersil has some new versions of its voltage references based on technology Xicor developed for depositing a precise charge on a floating gate.

The most interesting is Intersil’s X60008-41, which provides a precise 4.096-V reference. It provides precise 1-mV resolution when used with a 12-bit analog-to-digital converter (ADC). It’s possible to make the reference so precise because the technology enables Intersil to set the reference voltage in 250- µV increments.

The most tightly controlled versions of Intersil’s Low Power FGA products run on 500 nA. They claim 0.01% initial accuracy, a 1-ppm/ °C temperature coefficient (TC), a 10-ppm/ √ thousand-hour long-term drift, and 30- µV p-p noise. Compared to band-gaps, that’s four times better on accuracy, three times better on TC, six times better on drift, 25% better on noise, and 140 times less current.

Compared to buried zeners, the Intersil references are five times better on accuracy, five times better on TC, and equivalent on drift. Their noise is 50% higher than buried zeners, but supply current is 3000 times lower.

The X60008-41 costs $6.15 in 1000-unit quantities. More loosely specified versions cost as little as $0.99.


TAGS: Intersil
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