Loop powered transmitter with a single tap data isolation transformer and unipolar voltage converters

摘要

A loop-powered transmitter includes a data isolation transformer including primary and secondary windings and an analog-to-digital converter (ADC) to convert a sensor signal to a digital value. The transmitter also includes a first microcontroller coupled between a multi-signal interface of the ADC and only one tap of the primary winding of the data isolation transformer, and a second microcontroller coupled to the secondary winding of the data isolation transformer. The first microcontroller is configured to receive the digital value from the ADC over the multi-signal interface and to provide data indicative of the digital value via a single output data line through the tap of the primary winding of the data isolation transformer to the second microcontroller. Unipolar voltage converters may also be included in the transmitter along with a current limiting resistor for the data isolation transformer to reduce the risk of saturating the data isolation transformer.