CROSS-REFERENCE TO RELATED APPLICATION(S)

This application relates to the application entitled “Transmitter For Dual Communication Over An Isolation Channel”, naming Carlos Jesus Briseno-Vidrios et al. as inventors, application Ser. No. 17/066,244, filed Oct. 8, 2020, and this application relates to the patent application entitled “Interface For Passing Control Information Over An Isolation Channel” naming Michael R. May et al. as inventors, application Ser. No. 17/066,251, filed Oct. 8, 2020, all of which applications were filed on the same day as the present application and all of which applications are incorporated herein by reference.

BACKGROUND

Field of the Invention

The invention relates to isolation technology and more particularly to communication across an isolation barrier.

Description of the Related Art

Isolation communication channels are utilized in various applications where necessary to prevent current flow between isolated electric circuits by using an isolation barrier while still maintaining communication between the circuits. The isolation may be required for signal isolation, safety, or for other reasons. Communication between isolated circuits has typically involved a transmitter and receiver communicating over an isolation communication channel to provide, e.g., control information between the different voltage domains. The isolation communication channel may be implemented, e.g., using capacitive, inductive (transformers), or optical (opto-isolators) isolation techniques. In a typical isolation application, a control system provides one or more control signals for controlling a load system. During normal operation, a large DC or transient voltage difference may exist between the domain of the control system and the domain of the load system, thus requiring an isolation barrier between the control system and the load system. Isolation of the circuits in the separate voltage domains using an isolation barrier prevents damaging currents from flowing between the control system and the load system by a direct conduction path, while the isolation communication channel allows communication between the two systems.

FIG.1illustrates a prior art system100that includes an isolated gate driver101. The gate driver101receives control information for driving a gate signal of a high-power transistor102that is electrically isolated from the control functionality providing the control information. In the exemplary system100, controller103, which may be a microprocessor, microcontroller, or other suitable processing device, operates in a first domain (i.e., a domain including VDD1and VDD2). The controller103provides a gate signal to control a load system operating in a second domain i.e., a domain including VDD3and VDD4. The isolation barrier electrically isolates the primary side including VDD1(e.g., less than twenty volts) and VDD2(e.g., less than twenty volts) and devices coupled thereto, from the secondary side including VDD3(e.g., tens of volts) and VDD4(e.g., hundreds of volts) and devices coupled thereto.

The isolated gate driver101includes a transmitter circuit106and a receiver circuit108, which communicate over an isolation communication channel109. In the system100, controller103supplies gate information (GATE) to the transmitter circuit106in the first voltage domain. The transmitter circuit106transmits the gate information to the receiver circuit108in the second voltage domain. The receiver circuit108uses the gate information to generate a gate drive signal120to drive the high-power transistor102that is used to control a system load.

While the isolated gate driver allows communication across the isolation barrier, improvements in such communication is desirable to provide more precise control over the system load.

SUMMARY OF EMBODIMENTS OF THE INVENTION

Accordingly, in one embodiment a method includes receiving a signal transmitted across a single isolation communication channel as a received signal. The method further includes demodulating the received signal to determine respective values for gate information and configuration information contained in the received signal based on which of four states the received signal represents.

In another embodiment, an apparatus includes one or more input terminals to receive a signal transmitted across an isolation communication channel. A demodulator circuit is coupled to the one or more input terminals to demodulate a received signal to obtain gate information and to obtain configuration information. Respective values of the gate information and the configuration information are determined according to which one of four states the demodulator circuit detects in the received signal.

In another embodiment an integrated circuit includes aa demodulator to demodulate a signal received from an isolation communication channel to obtain gate information and configuration information simultaneously transmitted over the isolation communication channel. The demodulator includes a plurality of demodulation paths. The signal includes a first state in which the signal oscillates at a first frequency for a first bit time, a second state wherein the signal oscillates at different frequencies during a second bit time, a third state in which the signal oscillates at a third frequency lower than the first frequency during at least a portion of a third bit time, and a fourth state in which the signal is steady state for a fourth bit time. An envelope detector in one of the demodulation paths detects the second state.

