Compensation circuit for current peaking reduction in notification appliances
View Patent ↗A system and apparatus to reduce current peaking in notification appliances are described. The apparatus may include a current peaking compensation circuit comprising two or more transistors and one or more capacitors configured to reduce a start-up frequency of a pulse-width modulated signal during a first time period and to add a time constant decaying voltage across a resistor divider network to increase a reference voltage during the first time period. Other embodiments are described and claimed.
1. A current peaking compensation circuit, comprising:
a first transistor;
a first capacitor coupled to the first transistor wherein a gain of the first transistor is multiplied by a capacitance of the first capacitor to generate a time constant for the current peaking compensation circuit; and
a resistor divider circuit electrically coupled to said first transistor, wherein the current peaking compensation circuit is configured to reduce a start-up frequency of a pulse-width modulated signal during a first time period and to add a time constant decaying voltage across the resistor divider network to increase a reference voltage during the first time period.
2. The current peaking compensation circuit of claim 1 , comprising a second transistor coupled to the first capacitor and the first transistor, said second transistor configured to discharge the first capacitor after the first time period.
3. The current peaking compensation circuit of claim 1 , wherein the first time period comprises a start-up time of the pulse-width modulated signal.
4. The current peaking compensation circuit of claim 1 , wherein the time constant decaying voltage comprises an exponentially decaying voltage configured to decay from a rail voltage to a reference voltage.
5. The current peaking compensation circuit of claim 1 , wherein the pulse-width modulated signal is configured to periodically turn on and off an optical element of a notification appliance, wherein the optical element comprises a xenon bulb or strobe.
6. A notification appliance, comprising:
one or more optical elements;
an optical element driving circuit electrically communicating with said one or more optical elements and configured to drive the one or more optical elements; and
a current peaking circuit electrically communicating with said driving circuit and configured to reduce a start-up frequency of a pulse-width modulated signal during a first time period to enable substantially constant current operation of the notification appliance.
7. The notification appliance of claim 6 , wherein the current peaking circuit is configured to add a time constant decaying voltage across a resistor divider network to increase a reference voltage during the first time period, wherein the first time period comprises a start-up time of the pulse-width modulated signal.
8. The notification appliance of claim 7 , wherein the time constant decaying voltage comprises an exponentially decaying voltage configured to decay from a rail voltage to a reference voltage.
9. The notification appliance of claim 6 , wherein the current peaking circuit comprises:
a first transistor having an emitter, a base and a collector, the first transistor is an NPN transistor configured as a capacitance multiplier; and
a second transistor configured to reset a first capacitor after the first time period, wherein the second transistor comprises a PNP transistor having an emitter, a base and a collector, wherein the collector of the second transistor is coupled to the first capacitor and the base of the first transistor.
10. The notification appliance of claim 9 , wherein a gain of the first transistor is multiplied by a capacitance of the first capacitor coupled to the base of the first transistor to generate an amplified time constant for the current peaking circuit.
11. The notification appliance of claim 9 , wherein a collector resistor is used on the first transistor, to control the amplitude of the saturated output reference voltage.
12. The notification appliance of claim 6 , wherein the pulse-width modulated signal is generated by the optical element driving circuit and is configured to periodically turn on and off the one or more optical elements of the notification appliance, wherein the one or more optical elements comprise one or more xenon bulbs or strobes.
13. A system, comprising:
one or more current regulated power supplies; and
a plurality of notification appliances, wherein one or more of the notification appliances comprises a current peaking circuit, the current peaking circuit configured to reduce a start-up frequency of a pulse-width modulated signal during a first time period to enable substantially constant current regulated operation of the notification appliance without adversely affecting current output nor affect the amount of output power delivered.
14. The system of claim 12 , wherein the current peaking circuit is configured to add a time constant decaying voltage across a resistor divider network to increase a reference voltage during the first time period, wherein the first time period comprises a start-up time of the pulse-width modulated signal, wherein the time constant decaying voltage comprises an exponentially decaying voltage configured to decay from a rail voltage to a reference voltage.
15. The system of claim 12 , wherein the current peaking circuit comprises a first transistor having an emitter, a base and a collector, the first transistor comprising an NPN transistor configured as a capacitance multiplier wherein a gain of the first transistor is multiplied by a capacitance of a first capacitor coupled to the base of the first transistor to generate a time constant for the current peaking circuit.
16. The system of claim 14 , wherein the current peaking circuit comprises a second transistor configured to reset the first capacitor after the first time period, wherein the second transistor comprises a PNP transistor having an emitter, a base and a collector, wherein the collector of the second transistor is coupled to the first capacitor and the base of the first transistor.
17. The system of claim 12 , wherein the pulse-width modulated signal is generated by an optical element driving circuit and is configured to periodically turn on and off one or more optical elements of the notification appliance, wherein the one or more optical elements comprise one or more xenon bulbs or strobes.