Switching voltage regulator for an interface circuit in a telephone subscriber line

A switching voltage regulator for an interface circuit in a telephone subscriber line for controlling the on/off states of an electronic switch which includes first and second transistors interconnected in a Darlington arrangement, the regulator comprising:

• a first bistable storage cell having a non-inverting output and an inverting output, and set and reset inputs for respectively receiving an on signal and an off signal for turning the swtich on and off;
• second and third bistable storage cells each having a non-inverting output, a reset input, and a set input the set input of the second storage cell being coupled to the non-inverting output of the first storage cell, the set input of the third storage cell being coupled to the inverting output of the first storage cell, the second and third bistable storage cells changing state on a negative-going transition of the signal applied to the respective set input;
• an ON-state sensor coupled to the collector of the first transistor;
• an OFF-state sensor coupled to the base of the first transistor;
• a first current extractor device coupled to the base of the first transistor;
• a second current extractor device coupled to the base of the second transistor;
• first, second and third current sources each having an output;
• first and second current amplifiers respectively coupled to the outputs of the first and second current sources;
• the first amplifier having outputs coupled to the first and second extractor devices, the second amplifier having an output coupled to the base of the second transistor and the output of the third current source being coupled to the base of the second transistor;
• the first amplifier being coupled to the output of the third storage cell and the second amplifier being coupled to the output of the second storage cell;
• the second and third storage cells having their reset inputs respectively coupled to the ON-state sensor and the OFF-state sensor;
• the first current source being coupled to the inverting output of the first storage cell;
• the second current source and the third current source being coupled to the non-inverting output of the first storage cell.

A switching voltage regulator comprising:

• first and second transistors interconnected in a Darlington arrangement;
• an ON-state sensor coupled to the collector of the first transistor;
• an OFF-state sensor coupled to the base of the first transistor;
• a first current extractor coupled to the base of the first transistor;
• a second current extractor coupled to the base of the second transistor;
• control means coupled to receive an on signal for turning the first and second transistors on, an off signal for turning the first and second transistors off, and coupled to a source of power, the base of the second transistor, the ON-state sensor, the OFF-state sensor, the first current extractor and the second current extractor;
• the control means, in response to the on signal, coupling current from the source of power to the base of the second transistor to turn the first and second transistors on and the ON-state sensor on, the control means in response to an ON-state signal from the ON-state sensor turning the ON-state sensor off;
• the control means in response to an off signal ceasing coupling of current from the power source to the base of the second transistor and turning the first and second current extractors on to cause the first and second transistors to turn off, and turning the OFF-state sensor on, the control means in response to an OFF-state signal from the OFF-state sensor turning the first and second current extractors off and the OFF-state sensor off.

A switching voltage regulator comprising:

• first and second transistors interconnected in a Darlington arrangement;
• an ON-state sensor coupled to the collector of the first transistor and providing an ON-state signal when the first transistor is on;
• an OFF-state sensor coupled to the base of the first transistor and providing an OFF-state signal when the first transistor is off;
• a first current extractor coupled to the base of the first transistor;
• a second current extractor coupled to the base of the second transistor;
• a first current amplifier coupled to a source of power, the first and second current extractors and the OFF-state sensor;
• a second current amplifier coupled to the source of power and to the ON-state sensor;
• a first switch coupled between the source of power and the first amplifier;
• a second switch coupled between the source of power and the second amplifier;
• a third switch coupled between the source of power and the base of the second transistor;
• logic circuitry coupled to receive an on signal and an off signal, and the ON-state signal from the ON-state sensor and the OFF-state signal from the OFF-state sensor and coupled to the first, second and third switches and the first and second current amplifiers;
• the logic circuitry:
• turning the first switch on in response to the on signal and off in response to the off signal;
• turning the second and third switches on in response to the off signal and off in response to the on signal;
• turning the first current amplifier off in response to the OFF-state signal;
• and
• turning the second current amplifier off in response to the ON-state signal;
• the first current amplifier when the first switch is turned on turning the first and second current extractors on and the OFF-state sensor on, and when turned off turning the first and second current extractors off and the OFF-state off;
• the second current amplifier when the second switch is turned on turning the ON-state sensor on and the second current amplifier on, and when turned off turning the ON-state sensor off.