A fast response time, self-activating, adjustable threshold limiter including a limiting element LE, a first coupling element CE.sub.1 electrically connected from a signal node of LE to a control input of LE, and a second coupling element CE.sub.2 electrically connected from the control input of LE to a nominal node of LE. An initial bias (control) voltage is also supplied to the control input of LE to dynamically control the limiting threshold for the limiter. Embodiments include usage of self-activating adjustable power limiters in combination with series switch components in a switch circuit in lieu of conventional shunt switches.

A fast response time, self-activating, adjustable threshold limiter including a limiting element LE, a first coupling element CE.sub.1 electrically connected from a signal node of LE to a control input of LE, and a second coupling element CE.sub.2 electrically connected from the control input of LE to a nominal node of LE. An initial bias (control) voltage is also supplied to the control input of LE to dynamically control the limiting threshold for the limiter. Embodiments include usage of self-activating adjustable power limiters in combination with series switch components in a switch circuit in lieu of conventional shunt switches.

The present disclosure relates to a first circuit for measuring a first current, the first circuit including a current step-down circuit, a logarithmic comparator circuit, and a differential voltage amplifier circuit. A first input of the current step-down circuit is configured to receive the first current, and a first output of the current step-down circuit is configured to provide a ratiometric step-down current to a first logarithmic amplifier via a current mirror assembly. The logarithmic comparator circuit includes the first logarithmic amplifier, configured to convert the ratiometric step-down current into a logarithmic first voltage, and a second logarithmic amplifier, configured to provide a logarithmic reference voltage. The differential voltage amplifier circuit is configured to compare the logarithmic first voltage with the logarithmic reference voltage.

The present disclosure relates to a first circuit for measuring a first current, the first circuit including a current step-down circuit, a logarithmic comparator circuit, and a differential voltage amplifier circuit. A first input of the current step-down circuit is configured to receive the first current, and a first output of the current step-down circuit is configured to provide a ratiometric step-down current to a first logarithmic amplifier via a current mirror assembly. The logarithmic comparator circuit includes the first logarithmic amplifier, configured to convert the ratiometric step-down current into a logarithmic first voltage, and a second logarithmic amplifier, configured to provide a logarithmic reference voltage. The differential voltage amplifier circuit is configured to compare the logarithmic first voltage with the logarithmic reference voltage.

An audio system is provided. The aspects include a notification appliance circuit (NAC) having one or more speakers configured to reproduce sound. The aspects include an amplifier circuit configured to drive the one or more speakers. The aspects include a relay circuit configured to selectively connect or disconnect the speakers to or from the amplifier circuit responsive to an enable amplifier control signal or a disable amplifier control signal, respectively. The aspects include a logic element configured to generate the enable amplifier control signal or the disable amplifier control signal responsive to an absence or a presence of an overcurrent condition in an output of the amplifier circuit, respectively. The aspects include an overcurrent detection circuit configurated to detect the absence or the presence of the overcurrent condition.

An audio system is provided. The aspects include a notification appliance circuit (NAC) having one or more speakers configured to reproduce sound. The aspects include an amplifier circuit configured to drive the one or more speakers. The aspects include a relay circuit configured to selectively connect or disconnect the speakers to or from the amplifier circuit responsive to an enable amplifier control signal or a disable amplifier control signal, respectively. The aspects include a logic element configured to generate the enable amplifier control signal or the disable amplifier control signal responsive to an absence or a presence of an overcurrent condition in an output of the amplifier circuit, respectively. The aspects include an overcurrent detection circuit configurated to detect the absence or the presence of the overcurrent condition.

An example detector cell includes a first current source circuit having a terminal. The detector cell includes a first transistor having a control terminal, a first terminal, and a second terminal coupled to the terminal of the first current source circuit. The detector cell includes a second current source circuit having a terminal coupled to the first terminal of the first transistor. The detector cell includes a first current mirror having a first terminal and a second terminal, the first terminal coupled to the terminal of the second current source circuit and the first terminal of the first transistor. The detector cell includes a second transistor having a control terminal, a first terminal, and a second terminal coupled to the terminal of the first current source circuit. The detector cell includes a third current source circuit having a terminal coupled to the first terminal of the second transistor. The detector cell includes a second current mirror having a first terminal coupled to the terminal of the third current source circuit and the first terminal of the second transistor and a second terminal coupled to the second terminal of the first current mirror.

An example detector cell includes a first current source circuit having a terminal. The detector cell includes a first transistor having a control terminal, a first terminal, and a second terminal coupled to the terminal of the first current source circuit. The detector cell includes a second current source circuit having a terminal coupled to the first terminal of the first transistor. The detector cell includes a first current mirror having a first terminal and a second terminal, the first terminal coupled to the terminal of the second current source circuit and the first terminal of the first transistor. The detector cell includes a second transistor having a control terminal, a first terminal, and a second terminal coupled to the terminal of the first current source circuit. The detector cell includes a third current source circuit having a terminal coupled to the first terminal of the second transistor. The detector cell includes a second current mirror having a first terminal coupled to the terminal of the third current source circuit and the first terminal of the second transistor and a second terminal coupled to the second terminal of the first current mirror.