The QT301 charge-transfer (QT) IC is a self-contained Capacitance-to-Analog-Converter (CAC) capable of detecting femotofarad level changes in capacitance. This part is designed primarily for stand-alone instrumentation applications. Primary applications include fluid level sensors, distance sensors, material detectors, transducer amplifiers for pressure and humidity sensing functions, and other uses requiring quantified capacitance data. Unlike other Quantum products, the QT301 does not process its acquired data. Its only output is raw, unprocessed data in filterable PWM form that can be translated into an analog voltage by a simple RC network. This allows the designer to treat the device as a CAC for measurement applications. The PWM range is set via two inputs that control the starting and ending point of the conversion range. For example, if the capacitance range of Cx is from 27pF to 38pF, the QT301 can be calibrated so that the PWM zero point occurs at 27pF, and the endpoint (255) occurs at 38pF. In this way, the PWM range is optimized for the zone of interest. These calibration points are stored in internal EEPROM and do not have to be reacquired after a power reset. This means that the resolution of the part can be compared easily to other methods that might otherwise require 12 or more bits of overall resolution. The device operates on demand via a sync input pin. The sync input can also be used to avoid external noise sources and cross-interference from adjacent QRG capacitive sensors. Unique among capacitance sensors, this device features spread-spectrum burst modulation, permitting extremely high noise rejection characteristics for very robust signals even in high EMI environments.