Tiny 16-Bit Delta Sigma ADC from Linear Technology

14th November 2007

ES Admin

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Linear Technology has introduced the LTC2450, a 16-bit delta sigma analog-to-digital converter (ADC) in an ultra-tiny 2mm x 2mm DFN package that enables performance upgrades to lower resolution systems. Designers of portable and space-constrained applications typically trade off space with performance, leading to use of microcontrollers with internal ADCs or lower resolution ADCs with preamplifier circuitry. These designs are typically complex and lag in performance due to larger linearity errors, greater noise, or other unguaranteed specifications.

In only 4mm2 area, the versatile LTC2450 achieves excellent 16-bit DC performance of 2LSB integral nonlinearity error, 1.4uVRMS noise and 0.01% gain error. The tiny size and guaranteed 16-bit resolution allows designers to easily replace an embedded system's integrated ADC or a lower performance ADC and its preamplifier circuitry. Using the 2.7V to 5.5V supply voltage as the reference, the LTC2450 draws just 500uA of supply current, minimizing power loss. After automatically entering a shutdown mode, supply current is reduced to less than 1uA, further preserving battery power. By controlling the duration between conversions, the LTC2450's power dissipation can be reduced to 50uW at a 1Hz output rate. An internal oscillator allows conversion rates up to 30 per second, making it easy to measure temperature, pressure, voltage, or other low-frequency sensor outputs.

The LTC2450 communicates via a simple 3-wire SPI-compatible interface while measuring a single-ended analog input that may extend from ground to VCC. The LTC2450 includes continuous internal offset and full-scale calibration of the input signal, ensuring accuracy over time and over the full operating temperature range. Linear Technology's No Latency Delta Sigma™ design allows the ADC to multiplex several inputs with no delay in reading the output data. The LTC2450 incorporates a proprietary sampling network that reduces the input sampling current to less than 50nA, making possible a wide range of input protection and filter circuits.