18-bit, 2.5-Msps SAR ADC achieves 99.8-dB SNR

April 13, 2012 // By Paul Buckley
Linear Technology Corporation has introduced what the company claims to be the industry’s fastest 18-bit no cycle latency SAR analog-to-digital converter. The LTC2389-18 achieves 99.8 dB SNR and -116 dB THD at sample rates up to 2.5 Msps.

Operating from a single 5 V supply the LTC2389-18 supports three pin-configurable analog input ranges, easily interfacing to multiple signal chains with a single device. For the highest SNR performance, the LTC2389-18 can be configured for fully differential (±4.096V) inputs. The pseudo-differential unipolar (0 V to 4.096 V) and bipolar (±2.048 V) analog input ranges enable lower power single-ended drive and benefit from the reduction of unwanted signals common to both inputs. The LTC2389-18 is well suited for demanding designs that require maximum signal swings at low power levels in noisy industrial environments.

The LTC2389-18 features DC performance of ±3LSB INL (max), ±10LSB offset error and 18 bits no missing codes resolution. The LTC2389-18 also features a 4.096 V precision internal reference with a 20 ppm/°C (max) temperature coefficient, providing space savings for high density designs.

The LTC2389-18 dissipates 162.5 mW at 2.5 Msps and features a shutdown mode that reduces power dissipation to 75 µW when not converting. The true no latency operation enables accurate one shot measurements even after lengthy idle periods with no minimum sample rate requirement. The LTC2389-18 provides a flexible digital interface supporting 2.5 Msps throughput with parallel interface and 1.9 Msps throughput with serial SPI interface at I/O voltages from 1.8 V to 5 V.

The LTC2389-18 is the first in a family of pin- and software-compatible 18-/16-bit high performance, SAR ADCs with speeds ranging from 250 ksps to 2.5 Msps.

Specifications are guaranteed over the -4 to 125°C temperature range and the devices are available in 48-pin 7 mm x 7 mm LQFP and QFN packages. The LTC2389-18 is priced at $33.90 each in 1,000 piece quantities.

More information about the LTC2389 SAR ADC at