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US 8,803,117 B2Granted
Apparatus and method for non-latching, bi-directional communication over an electrically isolated data link
AssigneeMotorola Solutions, Inc.
InventorsDavid W. Wallis, James R. West
Life of this patent
Estimating the term…
Abstract
An isolation apparatus and method are provided for bi-directional communication over a single wire link without circuit latch up. The isolation is provided by two identical but independent switching circuits designed to eliminate latch up while controlling two optical isolators in a bi-directional mode of operation.
Claims20
An isolation circuit, comprising:
- first and second split data lines for bi-directional operation, wherein both the split data lines are coupled to open drain or open collector devices for preventing latch up by operating one of the open drain or open collector devices to switch a cathode of an optocoupler LED from a logic high to a logic low while simultaneously operating the other open drain or open collector device to switch an anode of the optocoupler LED from a logic high to a logic low, thereby maintaining the optocoupler LED off.
An isolation circuit for a communication device, comprising:
- first and second optical, RF devices;
- first, second third, and fourth buffers coupled to the first and second optical, RF devices, the first, second, third and fourth buffers being either open drain or open collector devices, wherein:
- the first buffer is coupled to a cathode of the first optical, RF device;
- the second buffer is coupled to an anode of the first optical, RF device;
- the third buffer is coupled to a cathode of the second optical, RF device;
- the fourth buffer is coupled to an anode of the second optical, RF device;
- and
- the first and second buffers maintain the first optical, RF device off by providing logic level low to the anode and cathode of the first optical, RF device during data flow in a first direction;
- and
- the third and fourth buffers maintain the second optical, RF device off by providing logic level high to the anode and cathode of the second optical, RF device during data flow in a second direction.
7 more elements
An isolation circuit, comprising:
- first and second optocouplers (110, 120) having first and second LEDs respectively;
- first, second third, and fourth buffers (130, 140, 150,160) coupled to the first and second optocouplers, the first, second, third and fourth buffers being either open drain or open collector devices, wherein:
- the first buffer (130) is coupled to the cathode of the first LED
- the second buffer (140) is coupled to an anode of the first LED;
- the third buffer (150) is coupled to the cathode of the second LED;
- the fourth buffer (160) is coupled to the anode of the second LED;
- and
- the first and second buffers maintain the first LED off by providing logic level low to the anode and cathode during data flow in a first direction;
- and
- the third and fourth buffers maintain the second LED off by providing logic level high to the anode and cathode of the second LED during data flow in a second direction.
7 more elements
An isolation circuit, comprising:
- first and second optocouplers being used as a bi-directional isolator, the first optocoupler having an LED1 under control of a transistor of the second optocoupler, and the second optocoupler having an LED2 under the control of a transistor of the first optocoupler;
- first and second data lines (D1, D2) being independently buffered to the LED1 and LED2 respectively;
- a first open drain, collector device (130) for switching the data line (D1), operating as an output, from supply to GND while switching the cathode side of the LED1 from supply to GND;
- a second open drain, collector device (140) for simultaneously switching the anode of LED1 from supply to GND, thereby maintaining the potential difference across LED1 at 0V dc, thereby preventing LED1 from lighting and latching the other circuit;
- a third open drain, collector device (150) for switching the data line (D2), operating as an output, from supply to GND while switching the cathode side of the LED2 from supply to GND;
- and
- a fourth open drain, collector device (160) for simultaneously switching the anode of LED2 from supply to GND, thereby maintaining the potential difference across LED2 at 0V dc, thereby preventing LED2 from lighting and latching the other circuit.
4 more elements
A method for isolating data lines, comprising:
- splitting data lines for bi-directional operation, wherein both the split data lines are coupled to open drain or open collector devices for preventing latch up by operating one of the open drain or open collector devices to switch a cathode of an optocoupler LED at the first side of the circuit from logic high to how and simultaneously operating the other open drain or open collector device to switch the anode of the optocoupler LED from logic high to low;
- and
- deploying open drain or open collector devices at in an independently supplied and grounded circuit to enable bi-directional operation.
A method for isolating bi-directional data lines over a single wire link, comprising:
- splitting first and second bi-directional data lines between two identical but independent first and second switching circuits respectively;
- controlling a first LED with the first switching circuit, the first switching circuit being controlled by the second data line, the first switching circuit simultaneously switching the anode and the cathode of the first LED;
- controlling the second LED with the second switching circuit, the second switching circuit being controlled by the first data line, the second switching circuit simultaneously switching the anode and the cathode of the second LED;
- turning the first LED on with the first switching circuit on while maintaining the second LED off with the second switching circuit;
- and
- turning the second LED on with the first switching circuit while maintaining the first LED off with the first switching circuit.
3 more elements
Dependencies are inferred from the claim text.