Optocoupler system with reduced power consumption and pulse width distortion
View Patent ↗According to one embodiment, there is provided an optocoupler system configured to generate current signals having high, low and no amplitude portions in response to the receipt of logic high and low input signals. The varying amplitude portions of the current signals are used to drive other portions of the isolation circuitry, and result in reduced power consumption and dissipation, as well as reduced pulse width distortion.
1. A method of reducing power dissipation and reducing pulse width distortion in an optocoupler system, comprising:
providing an input signal having high and low states to the optocoupler system;
generating first and second current signals corresponding to the high and low states of the input signal, the first current signal comprising high and low portions, the second current signal comprising high and null portions;
generating, with a light source, first and second light signals corresponding to the respective high, low and null portions of the first and second current signals;
generating, with a light detector operably configured in respect of the light source, first and second light detector current signals corresponding to the respective high, low and null portions of the first and second light signals;
converting the first and second light detector current signals into first and second voltage signals having respective high, low and null portions corresponding to the respective high, low and null portions of the first and second current signals;
reproducing the high and low states of the input signal at an output of the optocoupler system using the first and second voltage signals and the respective high, low and null portions corresponding thereto.
2. The method of claim 1 , further comprising generating a high reference voltage corresponding to the high state of the input signal and generating a low reference voltage corresponding to the low state of the input signal.
3. The method of claim 2 , further comprising comparing the first and second voltage signals to the high reference voltage and generating a first comparator signal on the basis of thereof.
4. The method of claim 3 , further comprising comparing the first and second voltage signals to the low reference voltage and generating a second comparator signal on the basis thereof.
5. The method of claim 4 , further comprising generating a detection logic signal on the basis of comparing the first and second comparator signals.
6. The method of claim 5 , further comprising employing a driver circuit and the detection logic circuit to reproduce substantially the input signal.
7. The method of claim 6 , further comprising further employing a watchdog logic circuit to receive and process the second comparator signal and provide an output signal to the detection logic circuit.
8. The method of claim 1 , further comprising providing the input signal as a series of pulses, where each pulse is characterized by a maximum amplitude corresponding to the high state, and durations of time in between the pulses are characterized by the low state.
9. The method of claim 8 , wherein transitions from the low state to the high state for each of the pulses results in the generation of high portions having durations of time T peak followed by low portions.
10. The method of claim 9 , wherein at least some pulses have a time period of about t 1 , durations of time between at least some adjoining pulses are each about t 2 , and T peak is less than t 1 or and t 2 .
11. The method of claim 8 , wherein transitions from the high state to the low state for each of the pulses results in the generation of high portions having durations of time T peak followed by null portions.
12. The method of claim 11 , wherein at least some pulses have a time period of about t 1 , durations of time between at least some adjoining pulses are each about t 2 , and T peak is less than t 1 or and t 2 .
13. The method of claim 8 , wherein transitions from the low state to the high state for each of the pulses results in the generation of high portions having durations of time T peak followed by low portions, and transitions from the high state to the low state for each of the pulses results in the generation of high portions having durations of time T peak followed by null portions, thereby minimizing pulse width distortion.
14. The method of claim 1 , wherein the high portion of the first current signal (ILEDH) has a maximum amplitude ranging between about 4 mA and about 20 mA.
15. The method of claim 1 , wherein the low portion of the first current signal (ILEDL) has a minimum amplitude greater than or equal to about 0.5 mA or less than about 50% of the high portion of the first current signal (ILEDH).
16. The method of claim 1 , wherein a first duration of time corresponding to the high portion is less than a second duration of time corresponding to the low portion.
17. The method of claim 1 , wherein current consumed by the light source during the null portions is about zero.
18. An optocoupler system, comprising:
a current driver logic circuit configured to receive an input signal having high and low states and to output first and second control signals corresponding to such high and low states;
a first current source configured to receive the first and second control signals and to output respective first and second current signals corresponding thereto, the first current signal comprising high and low portions, the second current signal comprising high and null portions;
a light source configured to receive the first and second current signals and to generate first and second light signals corresponding to the respective high, low and null portions thereof;
a light detector operably configured in respect of the light source to generate first and second light detector current signals corresponding to the respective high, low and null portions of the first and second light signals;
a transimpedance amplifier configured to receive the first and second light detector current signals and convert such signals into first and second voltage signals having respective high, low and null portions corresponding to the respective high, low and null portions of the first and second current signals;
a first reference amplifier configured to generate a high reference voltage corresponding to the high state of the input signal;
a second reference amplifier configured to generate a low reference voltage corresponding to the low state of the input signal;
a first comparator configured to receive the first and second voltage signals and compare same to the high reference voltage, and to generate a first comparator signal on the basis of such comparison;
a second comparator configured to receive the first and second voltage signals and compare same to the low reference voltage, and to generate a second comparator signal on the basis of such comparison;
a detection logic circuit configured to receive the first and second comparator signals, and to generate a detection logic signal on the basis of comparing such signals, and
a driver configured to receive the detection logic signal and produce a driver signal on the basis thereof, the driver and detection logic circuit together being configured to reproduce substantially the input signal.
19. The system of claim 18 , further comprising a watchdog logic circuit having an input configured to receive the second comparator signal and an output operably coupled to the detection logic circuit.
20. The system of claim 18 , wherein the light source is an LED.
21. The system of claim 18 , wherein the light detector is a photodiode.
22. The system of claim 18 , wherein the input signal comprises a series of pulses, where each pulse is characterized by a maximum amplitude corresponding to the high state, and durations of time in between the pulses are characterized by the low state.
23. The system of claim 22 , wherein transitions from the low state to the high state for each of the pulses results in the generation of high portions having durations of time T peak followed by low portions.
24. The system of claim 23 , wherein at least some pulses have a time period of about t 1 , durations of time between at least some adjoining pulses are each about t 2 , and T peak is less than t 1 or and t 2 .
25. The system of claim 22 , wherein transitions from the high state to the low state for each of the pulses results in the generation of high portions having durations of time T peak followed by null portions.
26. The system of claim 25 , wherein at least some pulses have a time period of about t 1 , durations of time between at least some adjoining pulses are each about t 2 , and T peak is less than t 1 or and t 2 .
27. The system of claim 22 , wherein transitions from the low state to the high state for each of the pulses results in the generation of high portions having durations of time T peak followed by low portions, and transitions from the high state to the low state for each of the pulses results in the generation of high portions having durations of time T peak followed by null portions, thereby minimizing pulse width distortion.
28. The system of claim 18 , wherein the high portion of the first current signal (ILEDH) has a maximum amplitude ranging between about 4 mA and about 20 mA.
29. The system of claim 18 , wherein the low portion of the first current signal (ILEDL) has a minimum amplitude greater than or equal to about 0.5 mA or less than about 50% of the high portion of the first current signal (ILEDH).
30. The system of claim 18 , wherein a first duration of time corresponding to the high portion is less than a second duration of time corresponding to the low portion.
31. The system of claim 18 , wherein current consumed by the light source during the null portions is about zero.