A/D converters simplify front-end signal conditioning

Milpitas, Calif. — Linear Technology Corp. claims its series of delta-sigma analog-to-digital converters (A/D converters) sport a novel front-end design that is able to directly digitize a wide range of sensors.

The A/D converters utilize the company's Easy Drive technology, which results in zero average differential input current, simplifying the design of front-end signal conditioning circuits and allowing the A/D converter to be driven directly from bridges, resistance temperature detectors (RTDs), thermocouples and other high impedance sensors.

These devices are said to be the first to directly and accurately measure high impedance input sources without the use of an internal buffer — eliminating the drawbacks of on-chip buffering.

For ease of use, the company incorporated an internal oscillator, transparent auto calibration and a wide input range that extends beyond the supply rails, by eliminating the need for initialization and calibration registers and invalid data associated with digital filter settling delays. Consequently, external RC networks with large time constants may now be placed directly in front of high resolution delta-sigma A/D converters without degrading their DC accuracy.

The LTC2480 provides 16-bit resolution and features exceptional accuracy with 2 ppm integral nonlinearity (INL), 1 ppm offset and 15 ppm full-scale errors.

The device also features an internal temperature sensor and programmable gain up to 256, making it suitable for temperature compensation of low level sensors.

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) are also available. 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.

All three parts are pin-compatible in the 3mm x 3mm 10-pin DFN package and are screened for both the commercial and industrial temperature ranges.

Pricing begins at $1.85 each for the LTC2480, $1.65 each for the LTC2482 and $2.45 each for the LTC2484. All prices are based on 1,000-piece quantities. Click here for the LTC2480 data sheet.

Linear Technology , 1-800-454-6327,

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