32-bit SAR ADC, 0.5ppm linearity, 148dB dynamic range

32-bit SAR ADC, 0.5ppm linearity, 148dB dynamic range

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LTC2500-32 is an ultra-high precision 32-bit successive approximation register (SAR) analogue-to-digital converter (ADC) that employs a new and enabling approach for precision measurement applications.
By Graham Prophet


The device blends the high accuracy and speed of Linear Technology’s (now part of Analog Devices) proprietary SAR ADC architecture with flexible integrated digital filters to optimize system signal bandwidth and ease analogue anti-aliasing filter requirements.


The LTC2500-32 simultaneously provides two outputs: firstly, a 32-bit low noise digitally filtered output that achieves up to 148 dB of dynamic range and secondly, a 32-bit 1 Msample/sec no-latency output comprising an over-range detection bit, a 24-bit representation of the input voltage difference, and a 7-bit representation of the common mode input voltage.


“…features enable state-of-the-art high precision measurements in noisy environments, such as in industrial automation applications…”


The no-latency output is inherently perfectly matched to the digitally filtered output, avoiding the mismatch and drift that typically occur in applications requiring an additional faster ADC to monitor signal integrity in parallel with a precision ADC.


The wide input common mode range and high CMRR enable the LTC2500-32 to interface signals with varying common mode, simplifying the analogue signal chain. Each of the two outputs provides a highly accurate representation of the voltage difference applied between the two input terminals.


The exceptional low noise density of LTC2500-32 produces 148 dB of dynamic range at 61 samples/sec and 104 dB at 1Msamples/sec. In addition to low noise, LTC2500-32 offers linearity of 0.5 ppm typical and 2 ppm guaranteed maximum INL, and negligibly low gain and offset drift over wide temperature ranges. In combination, these features enable state-of-the-art high precision measurements in noisy environments, such as in industrial automation applications. The integrated configurable digital filter offers seven filter types and 13 different down-sampling factors, providing users with a high level of flexibility to trade off bandwidth, filter response and noise performance for each application.


The LTC2500-32 is part of a family of ultrahigh precision SAR ADCs, which also includes the 32-bit LTC2508-32, providing digital filters optimized for data acquisition applications, and the 24-bit LTC2512-24, providing digital filters optimized for signal processing applications requiring a flat passband. The LTC2512-24 and LTC2508-32 provide a 14-bit no latency output for monitoring signal integrity and four downsampling factors for trading off bandwidth with dynamic range. The LTC2500-32 provides a broader range of filters and downsampling factors.


The LTC2500-32 in commercial and industrial (–40°C to 85°C) temperature grades is priced at $35.95 (1,000). The DC2222A evaluation board for the LTC2500 SAR ADC family is available at www.linear.com/demo or via a local Linear Technology office.


Analog Devices/Linear Technology; www.linear.com/product/LTC2500-32


next page; feature summary

Summary of features: LTC2500-32


104 dB SNR at 1 Msps

Dual output 32-Bit SAR ADC

◦ 32-bit digitally filtered low noise output

◦ 24-bit differential + 7-bit common mode 1Msps output with overrange detect

Configurable digital filter with synchronization

7 filter types: Sinc,1 Sinc,2 Sinc,3 Sinc,4 Spread-Sinc, Flat Passband, Averaging

Wide input common mode range

128dB CMRR

24-Lead 7mm x 4mm DFN package



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