18-bit ADC simplifies signal conditioning for ±10V industrial applications

October 02, 2013 // By Graham Prophet
LTC2338-18 is an 18-bit, 1Msample/sec, no-latency analogue-to-digital converter (ADC) with a wide ±10.24V fully differential, true bipolar input range for high voltage, industrial applications.

The device operates from a single 5V supply, achieves 100 dB SNR and -110 dB THD and features an internal 2.048V (20 ppm/°C max) reference and reference buffer. An input divider network scales and level shifts the input signal, eliminating complicated circuitry required to directly interface true bipolar signals.

The LTC2338-18 heads a pin- and software-compatible family of 18-bit serial SPI SAR ADCs with speeds ranging from 250 ksample/sec to 1 Msample/sec. A pin-compatible 16-bit and 18-bit family with pseudo-differential true bipolar inputs (LTC2328-18) will also be available. The proprietary internal reference buffer maintains less than 1 LSB error during sudden burst of conversions, enabling true one-shot operation after lengthy idle periods. These ADCs operate from a single 5V supply and consume 50 mW at 1 Msample/sec. Power further reduces linearly at slower sample rates. A shutdown mode dissipates 300 µW when idle.

The DC1908A demonstration board enables evaluation of the LTC2338 family in conjunction with the DC590B (QuikEval) or DC718C (PScope) data collection boards. The fully differential LTC2338-18 and pseudo differential LTC2328-18 families are available in small MSOP-16 packages in commercial, industrial and automotive temperature grades. Pricing begins at $29.10 (1,000).

Linear Technology; www.linear.com/product/LTC2338