18-Bit, 1.6Msps, Pseudo-Differential Serial SAR ADC Achieves 96.5dB SNR Performance & Low 18mW Power

Nov 7 2011 - MILPITAS, CA
  • Linear Technology Corporation introduces the LTC2369-18, a serial 18-bit, 1.6Msps pseudo-differential SAR analog-to-digital converter (ADC), which achieves impressive 96.5dB SNR and -120dB THD while supporting a 0V to 5V unipolar input range. The pseudo-differential input simplifies the ADC driver requirement, enabling single-ended drive while benefiting from the reduction of unwanted signals common to both inputs. This reduces complexity and lowers the power requirements in the signal chain. Operating from a 2.5V supply, the LTC2369-18 consumes only 18mW, with a low power shutdown mode that consumes just 2.25µW. When used in combination with the recommended single-ended ADC driver LT6202, the combined power dissipation is a mere 53mW, a 40% reduction from a fully differential drive circuit. The LTC2369-18 is the industry’s highest performing 18-bit pseudo-differential SAR ADC, featuring a maximum INL of ±2.5LSB with no missing codes and guaranteed specifications over the -40°C to 125°C temperature range.

    Complementing the LTC2369-18 is the pin- and software-compatible 16-bit, 2Msps LTC2370-16. The LTC2370-16 achieves outstanding 94dB SNR and ±0.85LSB maximum INL. The LTC2369-18 and LTC2370-16 are the first in a family of 18-/16-bit high performance pseudo-differential SAR ADCs with speeds ranging from 250ksps to 2Msps. They offer a user-friendly SPI interface, explicit Busy and Chain pins, I/O voltages from 1.8V to 5V and an internal oscillator that simplifies digital timing and minimizes external component count. Their true no-latency operation enables accurate one-shot measurements even after lengthy idle periods with no minimum sample rate required.

    The LTC2369-18 family of 18-/16-bit pseudo-differential SAR ADCs broadens the LTC2379-18 family of up to 102dB SNR, fully differential SAR ADCs introduced earlier this year. Linear’s complete portfolio of high performance pseudo and fully differential 18-/16-bit SAR ADCs with high SNR, fast throughput and low power dissipation is ideal for high performance medical, industrial and automotive applications. The LTC2369-18 and LTC2370-16 are available in small 16-lead MSOP and 4mm x 3mm DFN packages, and are priced at $29.95 each and $24.50 each, respectively in 1,000 piece quantities. To achieve uncompromised AC performance, we recommend the low noise, low power LT6202 ADC driver. We also recommend the LTC6655, a precision external reference with high accuracy of ±0.025% max, 2ppm/°C drift and low 0.25ppmP-P noise ideal for high precision applications. The DC1813A, an integrated demo board featuring the LT6202 ADC driver and LTC6655 reference, is available at www.linear.com or via a local Linear Technology sales office. For more information, visit www.linear.com/product/LTC2369.

    Summary of Features: LTC2369-18

    • 1.6Msps Throughput Rate
    • ±2.5LSB INL (Max)
    • Guaranteed 18-Bit No Missing Codes
    • Low Power: 18mW at 1.6Msps, 18µW at 1.6ksps
    • 96.5dB SNR (Typ) at fIN = 2kHz
    • –120dB THD (Typ) at fIN = 2kHz
    • Guaranteed Operation to 125°C
    • 2.5V Supply
    • Pseudo-Differential Unipolar Input Range: 0V to VREF
    • VREF Input Range from 2.5V to 5.1V
    • No Pipeline Delay, No Cycle Latency
    • 1.8V to 5V I/O Voltages
    • SPI-Compatible Serial I/O with Daisy-Chain Mode
    • Internal Conversion Clock
    • 16-Lead MSOP & 4mm x 3mm DFN Packages

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