ATCD-415A Thermocouple ADC

The ATCD-415A is used to condition and digitize up to fifteen analog thermocouple channels, three 4-wire RTD (dedicated for PT100) channels and offers a top-block built-in temperature sensor.

The ATCD-415A performs linearization for the selected cold junction sensor and thermocouple and compensates the thermocouple channel accordingly. Any of the three PT50/PT100 channels or top-block built-in temperature sensor can be selected as cold junction compensation.

The module offers programmable pull-down resistors for thermocouples isolated from the module ground.

At the heart of the ATCD-415A is a hard-wired state machine that oversamples all channels at a rate between 50 ksps and 100 ksps and digitally filters any noise above the user-programmable cutoff frequency. This is achieved using cascaded, 15-tap FIR filters with output rate decimation, followed by a final FIR or IIR filter. If IIR filtering mode is selected, the last digital filter in the filtering chain is an 8th or 16th order (selectable) Butterworth filter. If FIR mode is selected, the last digital filter in the filtering chain is a 49-tap Kaiser window, Beta 6 filter.

There are three independently configurable output streams per channel, allowing different sample rate, cutoff, and filter type to be selected for each output stream.

All signals are sampled simultaneously. When several channels are sampled at different sampling rates, at the start of an acquisition cycle all channels are aligned.