A/D convertor connects straight to sensors

16-channel delta-sigma analogue-to-digital convertor features a front-end design that can directly digitise a wide range of sensors.

Linear Technology has introduced the LTC2498 16-channel delta-sigma analogue-to-digital convertor (ADC), featuring a front-end design that can directly digitise a wide range of sensors.

The LTC2498's Easy Drive design results in zero average differential input current, allowing measurements of high impedance input sources without the use of an internal buffer.

This patented sampling scheme simplifies the design of front-end signal conditioning circuits and allows the ADC to be driven directly from bridges, RTDs, thermocouples and other high impedance sensors.

Rail-to-rail input signals can be directly digitised while maintaining excellent DC accuracy (2ppm integral nonlinearity).

The LTC2498 includes a high accuracy internal temperature sensor that offers 1/30C resolution and 2C absolute accuracy.

The ADC converts the output of the temperature sensor or the input multiplexer, which can be configured for 16 single-ended channels, eight differential channels, or combinations of both.

After a new channel is selected, the LTC2498's no latency delta-sigma digital filter settles in a single cycle.

The LTC2498 communicates via a four-wire SPI-compatible serial interface and performs conversions at rates up to 7.5 or 15Hz while using the internal oscillator.

The LTC2498 can be configured to reject line frequencies of 50Hz, 60Hz or simultaneous 50/60Hz, while maintaining 600nV RMS noise across the full input voltage range.

For lower resolution applications, Linear Technology is also introducing the LTC2496, a pin-compatible 16bit ADC.

The LTC2498 and LTC2496 are each available in QFN-38 (5 x 7mm) packages, offering a pin-compatible and code-compatible family for performance/cost optimisation.

Both Easy Drive delta-sigma ADCs are available in commercial and industrial temperature ranges.

Pricing begins at US $3.45 each for the LTC2498 and $2.65 each for the LTC2496, in 1000-piece quantities.

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