Protection circuit
AssigneeKabushiki Kaisha Toshiba
InventorsKazuhiro KATO, Takehito IKIMURA
Life of this patent
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Abstract
A circuit that protects against ESD and avoids an excessive power voltage drop during the protection operation includes a control circuit that is connected between power terminals and outputs a control signal when a voltage between the power terminals exceeds a predetermined value due to a surge current, and an asymmetric current transfer device including a PN junction reverse-biased by the power voltage between the power terminals, that is connected in series with the output current channel of a shunt transistor. The conductivity of the shunt transistor is controlled according to the control signal.
Claims20
A protection circuit, comprising:
- a first power terminal to receive a high potential voltage;
- a second power terminal to receive a low potential voltage;
- a control circuit connected between the first and the second power terminals which outputs a control signal when a voltage between the first and the second power terminals exceeds a predetermined threshold value;
- a shunt transistor having an output current channel connected between the first and the second power terminals, the shunt transistor having a conductive state thereof controlled according to the control signal;
- and
- an asymmetric current transfer device, including a PN junction reverse-biased by a power voltage between the first and the second power terminals, connected in series to the output current channel of the shunt transistor.
A protection circuit, comprising:
- a first power terminal;
- a second power terminal;
- a control circuit connected between the first and the second power terminals which outputs a control signal when a voltage between the first and the second power terminals exceeds a predetermined threshold value;
- a shunt transistor having an output current channel connected between the first and the second power terminals;
- and
- a diode connected in series to the output current channel of the shunt transistor between the first and the second power terminals.
A method for protecting a circuit, comprising:
- monitoring a power voltage value between a first power terminal and a second power terminal;
- outputting a control signal when the power voltage between the first and the second power terminals exceeds a predetermined threshold value;
- providing a current in an output current channel of a shunt transistor connected between the first and the second power terminals based on the control signal when the power voltage between the first and the second power terminals exceeds the breakdown voltage of an asymmetric current transfer device connected in series to the output current channel of the shunt transistor.
Dependencies are inferred from the claim text.