Linear Technology's LTC2480 series of delta-sigma analog-to-digital converters (ADCs) feature a novel front-end design that can directly digitize a wide range of sensors. Using the company's Easy Drive technology results in zero average differential input current, simplifying the design of front-end signal conditioning circuits and allowing the ADC to be driven directly from bridges, RTDs, thermocouples, and other high-impedance sensors. By directly and accurately measuring high-impedance input sources without using an internal buffer, the drawbacks of on-chip buffering are eliminated.
With the LTC2480 series, charge/discharge current pulses are balanced, and when summed over the entire conversion cycle, the total differential input current is zero, independent of the differential input voltage, common mode input voltage, reference voltage, or output code. The part provides 16-bit resolution and features 2 ppm INL, 1 ppm offset, and 15 ppm full-scale errors.
The device features an internal temperature sensor and programmable gain up to 256, making the device suitable for temperature compensation of low level sensors. Linear Technology also offers a version without the internal temperature sensor and programmable gain (LTC2482) as well as a 24-bit version with the temperature sensor, but without programmable gain (LTC2484). The entire family features no latency conversions for simple multiplexing, highly accurate internal oscillators with guaranteed line frequency rejection, precise DC specifications and the ease-of-use common to all of Linear Technology's LTC2400 ADC converters. Available in a 3- by 3-mm, 10-pin DFN package, prices start at $1.85 in lots of 1000. More information is available at www.linear.com.