32-bit SAR ADC, digitally filtered, 1Msps, 0-latency outputs

32-bit SAR ADC, digitally filtered, 1Msps, 0-latency outputs

New Products |
By Graham Prophet

This is often achieved by using a high resolution delta-sigma ADC and a high speed SAR ADC in the same system. The LTC2508-32 simplifies such hybrid ADC system design by simultaneously providing both a 32-bit low noise digitally filtered output and a 14-bit 1 Msample/sec no-latency output. Since these outputs are generated from a single 32-bit SAR ADC core, the high accuracy and high speed outputs are matched, even as the operating temperature, supply and stress vary. In contrast to traditional solutions employing two distinct unmatched ADCs, the combination of both accuracy and speed in the LTC2508-32 enables much higher system performance while reducing solution size and lowering component count.


The LTC2508-32 is suitable for applications that simultaneously require precision measurement and fast tracking of signals. The 3.5 ppm guaranteed maximum linearity, together with up to 145 dB of dynamic range, enables the LTC2508-32 to make precision measurements in the presence of noise. Simultaneously, the high speed 1 Msample/sec output provides a 14-bit differential and 8-bit common mode representation of the input signal, enabling sophisticated control loop designs with early detection mechanisms. The LTC2508-32 further improves system accuracy while simplifying signal conditioning design by directly digitizing the input signal over the full input range with over 120 dB of common mode rejection.


The LTC2508-32 features an integrated digital filter that can be configured to optimize the 32-bit high accuracy output’s noise performance and bandwidth, up to a maximum 145 dB of dynamic range at an output data rate of 61 sample/sec. The integrated digital filter offers a minimum 80 dB attenuation of out-of-band noise, relaxing analogue anti-aliasing filter requirements and significantly reducing system complexity. The reduced data rate of the digitally filtered output also eases communication with slow processors.


The LTC2508-32 dissipates 24 mW of power from a single 2.5V supply and comes in a 7 × 4 mm 24-lead DFN packagefor $8.95 (1000).


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Summary of Features: LTC2508-32


±0.5 ppm INL (typ)

145 dB dynamic range (typ) at 61 sps

131 dB dynamic range (typ) at 4 ksps

Guaranteed 32-bit no missing codes

Configurable digital filter with synchronization

Relaxed anti-aliasing filter requirements

Dual output 32-bit SAR ADC

32-bit digitally filtered low noise output

14-bit differential + 8-bit common mode 1 Msps no-latency output

Wide input common mode range

1.8V to 5V SPI-compatible serial I/O

Low power: 24 mW at 1 Msps

24-lead (7 × 4 mm) DFN package



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