Linear Technology introduces the LTC2412, a 24-bit No Latency Delta Sigma?ADC that offers two fully differential input channels and a differential reference input. Low noise of 800nVRMS provides 22.5 effective number of bits (ENOBs) over a ?.5V span and 16.9 ENOBs over a ?0mV span, which eliminates the need for PGAs. The wide input range easily handles sensor offsets and tare voltages, eliminating the need for front-end signal conditioning. This, together with the high resolution available, allows direct sensor connection for low cost, high accuracy data acquisition. The No Latency Delta Sigma architecture ensures single cycle digital filter settling even after a change in channels or input voltage step. Transparent auto calibration, on every conversion, ensures stable output codes with a total unadjusted error of 3ppm independent of time, temperature and supply. Operating from a single 2.7V to 5.5V supply, the LTC2412 consumes only 200 of supply current and automatically shuts down to 4uA between conversions benefiting portable or loop-powered applications. The LTC2412 accepts two differential inputs, which are converted alternately without needing to be programmed. The full-scale input span is ?.5VREF to 0.5VREF where the reference voltage can be anywhere between 0.1V and VCC for flexible ratiometric and remote sensing configurations. An on-chip oscillator provides a selectable notch filter of 50Hz or 60Hz with rejection better than 110dB and eliminates costly external components. An external clock source can be used for rejection of frequencies other than 50Hz or 60Hz and the converter will adapt automatically. The LTC2412 communicates through a 3-wire digital interface, which is compatible with the SPI protocol. The device is available in a 16-pin SSOP package, screened for industrial and commercial temperature ranges and pricing starts at $4.75 each in 1,000-piece quantities. Summary of Features: LTC2412
2-Channel Differential Input with Automatic Channel Selection
Differential Reference with Ground to VCC Common Mode Range
2ppm INL, No Missing Codes
800nVRMS Noise, 2.5ppm Full-Scale Error and 0.1ppm Offset Error
Internal Oscillator ?No External Components Required
Low Supply Current: 200Plus 4 Autosleep
110dB Min, 50Hz or 60Hz Notch Filter
Single Supply 2.7V to 5.5V Operation
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