Analog Devices Inc./Maxim Integrated

The LTC2444/LTC2445/LTC2448/LTC2449 are 8-/16- channel (4-/8-differential) high speed 24-bit No Latency ∆∑ ADCs. They use a proprietary delta-sigma architecture enabling variable speed/resolution. Through a simple 4-wire serial interface, ten speed/resolution combinations 6.9Hz/280nVRMSto 3.5kHz/25µVRMS(4kHz with external oscillator) can be selected with no latency between conversion results or shift in DC accuracy (offset, full-scale, linearity, drift). Additionally, a 2X speed mode can be selected enabling output rates up to 7kHz (8kHz if an external oscillator is used) with one cycle latency.Any combination of single-ended or differential inputs can be selected with a common mode input range from ground to VCC, independent of VREF. While operating in the 1X speed mode the first conversion following a new speed, resolution, or channel selection is valid. Since there is no settling time between conversions, all 8 differential channels can be scanned at a rate of 500Hz. At the conclusion of each conversion, the converter is internally reset eliminating any memory effects between successive conversions and assuring stability of the high order delta-sigma modulator.ApplicationsHigh Speed MultiplexingWeight ScalesAuto Ranging 6-Digit DVMsDirect Temperature MeasurementHigh Speed Data Acquisition

The LTC2461/LTC2463 are ultra tiny, 16-Bit analog to digital converters with an integrated precision reference. They use a single 2.7V to 5.5V supply and communicate through an I2C Interface. The LTC2461 is single-ended with a 0V to 1.25V input range and the LTC2463 is differential with a 1.25V input range. Both ADCs include a 1.25V integrated reference with 2ppm/°C drift performance and 0.1% initial accuracy. The converters are available in a 12-pin 3mm × 3mm DFN package or an MSOP-12 package. They include an integrated oscillator and perform conversions with no latency for multiplexed applications. The LTC2461/LTC2463 include a proprietary input sampling scheme that reduces the average input current several orders of magnitude when compared to conventional delta sigma converters.Following a single conversion, the LTC2461/LTC2463 automatically power down the converter and can also be configured to power down the reference. When both the ADC and reference are powered down, the supply current is reduced to 200nA.The LTC2461/LTC2463 can sample at 60 conversions per second and, due to the very large oversampling ratio, have extremely relaxed antialiasing requirements. Both include continuous internal offset and fullscale calibration algorithms which are transparent to the user, ensuring accuracy over time and the operating temperature range.ApplicationsSystem MonitoringEnvironmental MonitoringDirect Temperature MeasurementsInstrumentationData AcquisitionEmbedded ADC Upgrades