The 18-bit delta-sigma MCP3421 analog-to-digital converter (ADC) is the highest-resolution ADC available in an SOT-23 package, according to Microchip Technology Inc. The low-power device features an integrated voltage reference, oscillator, and programmable-gain amplifier (PGA), which reduces the need for external components and allows a smaller overall design footprint. The on-board PGA lets users select gains of 1, 2, 4, or 8 before the analog-to-digital conversion takes place, enabling very high-resolution conversion of even small input signals.
The MCP3421 uses an I2C-compatible serial interface. It operates from a single power supply from 2.7 to 5.5 V. The device draws only 155 µA at 5-V continuous conversion, making it well-suited for use in battery-operated equipment. Typical applications for the MCP3421 include industrial devices (portable instrumentation, pressure sensors, weigh scales, handheld meters and multimeters), medical (heart-rate monitors and blood glucose meters), consumer (weigh scales and handheld meters), and automotive (sensor interfaces and fuel gauges) (see the Figure). An evaluation board (MCP3421EV) is available for designers considering using the ADC.
The MCP3421 costs $1.71 each in 10,000-unit quantities. The MCP3421EV evaluation board costs $15.00.
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