USB isolator with advanced control features
AssigneeAnalog Devices, Inc.
InventorsEric C. Gaalaas, Mark Stewart Cantrell
Life of this patent
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Abstract
A USB-based isolator system conveys USB signals between a pair of galvanically isolated circuit systems and supports controlled enumeration by a downstream device on upstream USB signal lines. The isolator system provides a multi-mode voltage regulator to support multiple voltage supply configurations. The isolator system further provides control systems for each of the isolated circuit systems and provides robust control in a variety of start up conditions. Additionally, the isolator system includes refresh timers and watchdog mechanisms to support persistent operation but manage possible communication errors that can arise between the isolated circuit systems.
Claims31
An isolation system, comprising:
- a plurality of one or more isolation devices bridging an isolation barrier between an upstream side and a downstream side of the isolation barrier,
- a USB interface provided on an the upstream side of the isolation barrier, including a termination circuit having a pull up resistor,
- an isolator transceiver coupling the USB interface to the isolation devices, and
- an isolator transmitter provided on a the downstream side of the isolation barrier and configured to receive an enumeration transmit to the upstream side a control signal controlling which signal line of a pair of differential signal lines is to be connected to the pull up resistor,
- wherein the enumeration isolation system is configured to propagate the control signal propagates through at least one of the one or more isolation devices to the upstream side and controls switching of the pull up resistor in the termination circuit.
A method of communicating in a USB isolation system including a first side and a second side separated by an isolation barrier, comprising:
- transmitting, from the first side to the second side, a control signal across the isolation barrier through at least one isolation device;
- and
- receiving the control signal from the first side;
- and
- in response to receiving the control signal, controlling which signal line of a pair of differential signal lines is to be connected to a pull up resistor.
An integrated circuit, comprising:
- an isolation barrier separating a downstream side and an upstream side of the integrated circuit;
- and
- one or more isolation devices bridging an isolation barrier between the downstream and upstream sides,
- the downstream side including an isolator transmitter to transmit a control signal through at least one of the one or more isolation devices to the upstream side,
- the upstream side including
- a USB interface including a termination circuit having a pull up resistor,
- an isolator receiver to receive the control signal transmitted by the isolator transmitter on the downstream side, and
- a switch controller configured to control which signal line of a pair of differential signal lines is to be connected to the pull up resistor in the termination circuit according to the control signal.
Dependencies are inferred from the claim text.