Sensor communication discrete control considering EMC compliance for restraint control module

1. An electronic control unit comprising:

a Peripheral Sensor Interface 5 (PSI5) communications interface configured to communicate with a remote sensor using a current-modulated signal with PSI5 compliance upon a two-wire interconnection, the PSI5 communications interface including:

a signal driver configured to apply a signal voltage to a first signal terminal for driving current to the remote sensor via the two-wire interconnection;

a second signal terminal providing a return path for the current; and

a resistor within the return path of the PSI5 communications interface to induce a balance voltage on the second signal terminal, wherein the balance voltage has a magnitude corresponding to a magnitude of the signal voltage and an opposite polarity thereof, and wherein the resistor is defined by a drain-source on resistance of a field effect transistor having a gate terminal connected to the first signal terminal.

2. A restraint control module for a motor vehicle comprising the electronic control unit of claim 1 .

3. The electronic control unit according to claim 1 , wherein the resistor is connected between the second signal terminal and a chassis ground.

4. The electronic control unit according to claim 1 , wherein the gate terminal is connected directly to the first signal terminal of the PSI5 communications interface.

5. The electronic control unit according to claim 4 , further comprising a current limiting resistor connected between the gate terminal and the first signal terminal of the PSI5 communications interface.

6. An electronic control unit comprising:

a Peripheral Sensor Interface 5 (PSI5) communications interface configured to communicate with a remote sensor using a current-modulated signal with PSI5 compliance upon a two-wire interconnection, the PSI5 communications interface including:

a signal driver configured to apply a signal voltage to a first signal terminal for driving current to the remote sensor via the two-wire interconnection;

a second signal terminal providing a return path for the current;

a resistor within the return path of the PSI5 communications interface to induce a balance voltage on the second signal terminal, wherein the balance voltage has a magnitude corresponding to a magnitude of the signal voltage and an opposite polarity thereof, and wherein the resistor is defined by a drain-source on resistance of a field effect transistor; and

a switch configured to limit an amount of current between the second signal terminal and a ground.

7. The electronic control unit according to claim 6 , further comprising a current sensor configured to detect the amount of current between the second signal terminal and the ground; and

wherein the switch is controlled by the current sensor.

8. The electronic control unit according to claim 6 ,

wherein the switch is configured to selectively assert or de-assert a control voltage upon a gate of the field effect transistor to drive the field effect transistor between a low impedance state and a high impedance state.

9. The electronic control unit according to claim 1 , further comprising a signal amplifier having a signal input and a signal output, with the signal input coupled to the first signal terminal and the signal output coupled to the second signal terminal through the resistor.

10. A method for operating a Peripheral Sensor Interface 5 (PSI5) communications interface of an electronic control unit, the method comprising:

applying a signal voltage to a first signal terminal of the PSI5 communications interface to drive a signal current to a remote sensor via a two-wire interconnection;

receiving the signal current from the remote sensor by a second signal terminal of the PSI5 communications interface providing a return path for the signal current;

inducing a balance voltage upon the second signal terminal by a resistor within the return path, wherein the balance voltage has a magnitude corresponding to a magnitude of the signal voltage and an opposite polarity thereof, and wherein the resistor is defined by a drain-source on resistance of a field effect transistor; and

selectively changing a resistance of the resistor as a function of the signal voltage.

11. The method according to claim 10 , wherein the electronic control unit is configured for operation within a restraint control module for a motor vehicle.

12. The method according to claim 10 , wherein the resistor is connected between the second signal terminal and a chassis ground.

13. The method according to claim 10 ,

wherein selectively changing the resistance of the resistor further comprises selectively asserting a gate of the field effect transistor by the signal voltage.

14. The method according to claim 10 , further comprising:

sensing the signal current; and

driving the return path to a high-impedance state in response to the signal current exceeding a current threshold voltage.

15. The method according to claim 14 ,

wherein driving the return path to the high-impedance state further comprises selectively de-asserting a gate of the field effect transistor in response to the signal current exceeding the current threshold voltage.

16. The method according to claim 10 , wherein inducing the balance voltage upon the second signal terminal further comprises:

applying a bias signal to the second signal terminal by a signal amplifier, with the bias signal being a function of the signal voltage.