US 5,499,176 A · Pulse transformer circuit for isolating electrical signals

Abstract

A signal isolator circuit employing a pulse transformer overcomes the disadvantages of both prior art opto-coupler and pulse transformer signal isolator circuits by employing an active signal retrieval circuit which, in a higher accuracy configuration, repetitively performs the following steps on the electrical side of the pulse transformer where the signal information is required: 1) drives a current pulse into the pulse transformer; 2) samples or detects the voltage across the pulse transformer after it has been stabilized; 3) holds or stores the sampled voltage for a full cycle of operation; and, if necessary, 4) filters the sampled signal. On the other electrical side of the pulse transformer, the retrieval circuitry is configured such that when the pulse transformer is being driven by the current pulse, the voltage will be clamped by the source signal reset. In a lower accuracy configuration, the signal retrieval circuit of the present invention performs the same steps set forth above with the exception that, rather than sampling the voltage across the pulse transformer, the reflected impedance is detected as being either high or low, by some quantitative measure, and the detector output will be set to either a high or low voltage corresponding to the detected impedance.

Claims4

Dependent claims

A process for retrieving, as a target signal, a source signal that has been conveyed across an isolation boundary, the process comprising:

providing a puse transformer having a primary side to which the source signal is applied and having a secondary side from which the target signal is retrieved;
repetitively performing, in synchronization with a clocking signal, the following steps on the secondary side of the pulse transformer:
(1) driving a current pulse into the pulse transformer;
(2) sampling the voltage across the pulse transformer after it has stabilized but while the current pulse is still active;
and
(3) storing the sampled voltage for a full clock cycle;
and
performing the step on the primary side of the pulse transformer of clamping the voltage across the pulse transformer by the source signal during a portion of a clock cycle when the pulse transformer is being driven by the current pulse.

5 more elements

Dependencies are inferred from the claim text.

Pulse transformer circuit for isolating electrical signals

Life of this patent

Pulse transformer circuit for isolating electrical signals

Life of this patent

Abstract

Claims4