12-bit SAR ADC with SPI — 100k samples per second in a 14-SOIC
The Microchip MCP3204T-CI/SL is a 12-bit successive-approximation-register (SAR) ADC that samples at 100k samples per second over an SPI serial interface. It accepts either two or four input channels configured as pseudo-differential or single-ended, with an external voltage reference. The analog and digital supply rails share a single 2.7V to 5.5V range, which simplifies power routing on a mixed-signal board.
At 100k samples per second, the Nyquist limit is 50 kHz, so this ADC comfortably digitises audio-band sensor outputs, 50/60 Hz power-line monitoring, and slow-moving process-control loops. The SAR architecture gives no pipeline delay — each conversion completes in a single cycle, which matters for multiplexed inputs where you need a settled result per channel without a latency penalty.
Input flexibility: two or four channels, pseudo-differential or single-ended
The MCP3204T-CI/SL offers two pseudo-differential inputs or four single-ended inputs, selected via the SPI command word. The pseudo-differential mode references each measurement to a dedicated low-side pin, rejecting common-mode noise on the return path — useful when the sensor ground is remote from the ADC ground. The single-ended mode doubles the channel count for simpler voltage-sensing tasks like reading potentiometers or thermistor dividers.
The external reference allows the full-scale range to be scaled to match the sensor output, preserving the 12-bit resolution over a smaller input span.
The tape-and-reel variant (the 'T' suffix) is the standard ordering option for automated assembly; cut-tape quantities are also available for prototyping.