SAR ADC has speed and accuracy for instrumentation and control

Simplifying hybrid ADC system design in data acquisition, industrial control and medical instrumentation, without using a high resolution delta-sigma ADC and a high speed SAR (successive approximation register) ADC in the same system, the LTC2508-32 is a 32bit SAR ADC.

It provides both a 32bit low noise digitally filtered output and a 14bit 1Msample/s no latency output. These outputs are generated from a single 32bit SAR ADC core, meaning that the high accuracy and high speed outputs are matched, even as the operating temperature, supply and stress vary. Traditional solutions use two distinct unmatched ADCs. The LTC2508-32 enables much higher system performance while reducing solution size and lowering component count, claims the company.

The ADC can be used for applications that simultaneously require precision measurement and fast tracking of signals. The 3.5ppm guaranteed maximum linearity, together with up to 145dB of dynamic range, enables it to make precision measurements in the presence of noise. Simultaneously, the high speed 1Msample/s output provides a 14bit differential and 8bit common mode representation of the input signal, enabling control loop designs with early detection mechanisms. Signal conditioning design is simplified by directly digitising the input signal over the full input range with over 120dB of common mode rejection.

An integrated digital filter can be configured to optimise the 32bit high accuracy output’s noise performance and bandwidth, up to a maximum 145dB of dynamic range at an output data rate of 61sample/s. The integrated digital filter offers a minimum 80dB attenuation of out-of-band noise, relaxing analogue anti-aliasing filter requirements and is also claimed to reduce system complexity. The reduced data rate of the digitally filtered output also eases communication with slow processors.

The ADC dissipates 24mW of power from a single 2.5V supply. It is available now in a space saving 7.0 x 4.0mm 24-lead DFN package. Samples and demo boards are available on request.

http://www.linear.com/product/LTC2508-32

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