Generating a fast reset-signal using a fault-protection latch
AssigneePower Integrations, Inc.
InventorRobert Mayell
Life of this patent
Estimating the term…
Abstract
Methods and apparatuses are disclosed for monitoring an ac input for fault conditions. The ac input may be monitored by a latch-reset that uses the ac input to charge a line detection capacitor. The latch-reset may be configured such that the voltage at one end of the line detection capacitor drops below a line detection threshold voltage when the ac input is removed for longer than an allowable period of time or if the voltage of the ac input falls below an acceptable value. The drop in voltage at the end of the capacitor may cause an electrically coupled transistor to switch, thereby causing a reset-signal to be generated.
Claims27
A latch-reset for detecting a fault condition in an alternating current (ac) input voltage, the latch-reset comprising:
- a high-impedance circuit comprising an impedance element, a first diode, and a first resistor;
- a line detection capacitor coupled to the high-impedance circuit, wherein the line detection capacitor is configured to be charged by the ac input voltage through the impedance element and the first diode while the first diode is conducting, and wherein the line detection capacitor is configured to be discharged through the first resistor while the first diode is not conducting;
- and
- a transistor, wherein the transistor is configured to switch in response to a voltage at an end of the line detection capacitor dropping below a line detection threshold voltage, and wherein the transistor is further configured to cause a reset-signal to be generated in response to the transistor being switched.
A latch-reset for detecting a fault condition in an alternating current (ac) input voltage, the latch-reset comprising:
- an impedance element coupled to receive the ac input voltage;
- and
- a transistor, wherein the transistor is configured to switch in response to the ac input voltage dropping below an input voltage threshold, and wherein the transistor is further configured to cause a reset-signal to be generated when the transistor is switched.
A method for detecting a fault condition in an alternating current (ac) input voltage, the method comprising:
- receiving the ac input voltage at a high-impedance circuit, the high-impedance circuit comprising an impedance element, a first diode, and a first resistor;
- charging, using the ac input voltage, a line detection capacitor through the impedance element and the first diode, wherein the line detection capacitor is charged while the first diode is conducting;
- discharging the line detection capacitor through the first resistor, wherein the line detection capacitor is discharged while the first diode is not conducting;
- monitoring a voltage at an end of the line detection capacitor using a transistor, wherein the transistor is configured to switch in response to a voltage at the end of the line detection capacitor dropping below a line detection threshold voltage;
- and
- causing a reset-signal to be generated in response to the transistor being switched.
A power converter system, comprising:
- an ac bridge coupled to receive an ac input voltage and coupled to output a time-varying dc voltage;
- a power converter coupled to the ac bridge and coupled to receive the time varying dc voltage and to output a regulated dc output voltage;
- a controller coupled to the power converter and coupled to control the transfer of energy through the power converter;
- and
- a latch-reset coupled to receive the ac input voltage and coupled to output a reset signal to the controller in response to the ac input voltage dropping below an input voltage threshold, wherein the latch-reset comprises a high impedance element coupled to receive the ac input voltage.
Dependencies are inferred from the claim text.