Method of forming an over-voltage protection circuit and structure therefor
First Claim
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1. An over-voltage protection circuit comprising:
- an input configured to receive an input voltage;
an output;
a pass element transistor coupled between the input and the output and configured to couple the input voltage to the output;
a first circuit configured to disable the pass element transistor responsively to the input voltage being no less than a first value, the first circuit coupled to receive the input voltage and including a zener diode coupled to receive the input voltage, the first circuit including a resistor coupled in series with the zener diode and also including a another transistor coupled in parallel to the resistor wherein the first circuit is configured to enable the another transistor responsively to the input voltage being no less than the first value; and
a second circuit configured to disable the pass element transistor responsively to the input voltage being no less than a second value that is less than the first value, the second circuit coupled in parallel with the first circuit to receive the input voltage.
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Abstract
In one embodiment, an over-voltage protection circuit is configured to have two control circuits that respond at different values of the input voltage.
14 Citations
19 Claims
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1. An over-voltage protection circuit comprising:
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an input configured to receive an input voltage; an output; a pass element transistor coupled between the input and the output and configured to couple the input voltage to the output; a first circuit configured to disable the pass element transistor responsively to the input voltage being no less than a first value, the first circuit coupled to receive the input voltage and including a zener diode coupled to receive the input voltage, the first circuit including a resistor coupled in series with the zener diode and also including a another transistor coupled in parallel to the resistor wherein the first circuit is configured to enable the another transistor responsively to the input voltage being no less than the first value; and a second circuit configured to disable the pass element transistor responsively to the input voltage being no less than a second value that is less than the first value, the second circuit coupled in parallel with the first circuit to receive the input voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of forming an over-voltage protection circuit comprising:
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configuring a pass element of the over-voltage protection circuit to couple an input, voltage to an output of the over-voltage protection circuit; coupling a first circuit of the over-voltage protection circuit to receive the input voltage and configuring the first circuit to decouple the input voltage from the output responsively to a first value of the input voltage for the input voltage increasing at a first rate; coupling a second circuit of the over-voltage protection circuit in parallel with the first circuit to receive the input voltage and configuring the second circuit to decouple the input voltage from the output responsively to the input voltage increasing to no less than a second value at a second rate wherein the second value is greater than the first value; and coupling an output of the first circuit and an output of the second circuit to a first transistor wherein both the first and second circuits disable the first transistor responsively to the input voltage having a value that is less than the first value and wherein disabling the first transistor causes the pass element to couple the input voltage to the output and also changes the second value to a third value that is less than the second value. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification