US 6,130,813 A · Protection circuit for electronic devices

Abstract

For an electronic device having at least one power switch for each of two or more power sources such that the power switches can be selectively activated or deactivated depending on a signal supplied to them, a protection circuit having a current-sense circuit coupled to measure the current from the two or more power sources, and a latch for producing a switch deactivating signal and applying it to the switches in response to an over-current signal from the current-sense circuit can protect the switches and the electronic device from soft-short circuits and absolute short circuits. Bypass resistors coupled to the switches allow the electronic device to receive a small current ("pre-charge") before any of the switches are activated so that a comparator can test for the presence of various types of short circuits. Additionally, the precharging brings the electronic device to a higher voltage (as compared to no pre-charging) when one of the switches is activated, thereby helping to reduce in-rush currents. Blanking logic allows the protection circuit to tolerate certain in-rush currents by preventing the latch from triggering (e.g., supplying the latch with an under-current signal) for an appropriate time period.

Claims20

Dependent claims

A protection circuit for an electronic device having a first and a second switch, each switch operable to electrically connect a first power source and a second power source, respectively, to a load, and each switch adapted to receive a first and a second signal, respectively, for selectively activating and deactivating the respective switch, the protection circuit comprising:

a current-sense circuit coupled to the first and second switches, the current-sense circuit operable to measure a current supplied to the load through at least one of the first and the second switches, and operable to provide an over-current signal;
a latch coupled to the current-sense circuit, the latch operable to receive the over-current signal from the current-sense circuit, and provide a switch deactivating signal as the first signal and the second signal to the first and second switch, respectively;
a controller operable to provide at least one of an activating signal and a deactivating signal to each of the first switch and the second switch, the controller being coupled to the latch, the latch being operable to provide the switch deactivating signal to the controller, and the controller being operable to provide the switch deactivating signal as the first signal and the second signal to the first and second switch, respectively;
a comparator having an non-inverted input, an inverted input, and an output;
and
an output switch coupled to the output of the comparator and operable to be activated and deactivated by a comparator output signal.

3 more elements

A computer system comprising:

a processor;
a memory coupled to the processor;
a first switch operable to electrically connect a first power source to the processor and memory, the first switch adapted to receive a first signal for selectively activating and deactivating the first switch;
a second switch operable to electrically connect a second power source to the processor and memory, the second switch adapted to receive a second signal for selectively activating and deactivating the second switch;
and
a protection circuit including:
a current-sense circuit coupled to the first and second switches, the current-sense circuit operable to measure a current supplied to the processor and memory through at least one of the first and the second switches, and operable to provide an over-current signal;
a latch coupled to the current-sense circuit, the latch operable to receive the over-current signal from the current-sense circuit, and provide a switch deactivating signal as at least one of the first signal and the second signal to the first and second switch, respectively;
a controller coupled to the first switch and the second switch, the controller operable to provide at least one of an activating signal and a deactivating signal to each of the first switch and the second switch;
and
blanking logic coupled to the controller and the latch, the blanking logic operable to receive the at least one of an activating signal and a deactivating signal provided to each of the first switch and the second switch, and to prevent the latch from providing the switch deactivating signal when both the first switch and the second switch receive a deactivating signal.

8 more elements

Dependencies are inferred from the claim text.

Protection circuit for electronic devices

Life of this patent

Protection circuit for electronic devices

Life of this patent

Abstract

Claims20