The LTC2338-18 is part of a pin and software compatible family of 18-bit serial SPI SAR ADCs with speeds ranging from 250ksps to 1Msps. The pin-compatible LTC2328 16-bit and 18-bit family with pseudo differential true bipolar inputs offers 95dB SNR at 18-bits and 94dB SNR at 16-bits. 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 just 50mW at 1Msps. Power further reduces linearly at slower sample rates. A shutdown mode dissipates only 300μW when idle.