Sigma-Delta ADCs Generate Own Negative Power Supply

An instrumentation amplifier, a programmable gain amplifier, a multi-channel multiplexer, digital filters, and self- and system-calibration circuitry are all included on the 16-bit CS5521/23 buffered sigma-delta ADCs. The chips are designed to provide their own negative power supply, which enables the on-chip instrumentation amp to measure bipolar ground-referenced signals of less than or equal to ±100 mV.The devices' digital filters provide programmable output update rates of 1.88 Hz, 3.76 Hz, 7.51 Hz, 15 Hz, 30 Hz, 61.6 Hz, 84.5 Hz and 101.1 Hz when operating from a 32-kHz crystal. With a 100-kHz clock, the converters are capable of output update rates of up to 303 Hz. The filters are designed to settle to full accuracy within one conversion cycle.They offer buffered, bipolar/unipolar input ranges of 25 mV, 55 mV, 100 mV, 1V, 2.5V and 5V. Linearity error is just 0.0015% of full scale. Evaluation boards are available.