Battery-backed power interface transformer for low-power devices

Abstract

A power interface enables a low-power device to be powered from an alternating current (AC) wall receptacle or light socket with automatic backup battery charging. The power interface of an embodiment comprises a transformer module that receives an input signal. The device includes a battery module coupled to the transformer module, and the battery module includes battery charging circuitry coupled to a battery. The device comprises an output controller coupled to the transformer module and the battery module. The output controller includes detector circuitry that detects a state of the input signal. The output controller automatically controls coupling of one of a transformer module output and a battery module output to a device output according to the state of the input signal.

1 . A device comprising:
 a transformer module that receives an input signal;   a battery module coupled to the transformer module, the battery module comprising battery charging circuitry coupled to a battery; and   an output controller coupled to the transformer module and the battery module, wherein the output controller comprises detector circuitry that detects a state of the input signal, wherein the output controller automatically controls coupling of one of a transformer module output and a battery module output to a device output according to the state of the input signal.   
     
     
         2 . The device of  claim 1 , wherein the transformer module comprises transformer circuitry, wherein the transformer circuitry receives the input signal. 
     
     
         3 . The device of  claim 2 , wherein the transformer circuitry comprises a step-down transformer that reduces a voltage of the input signal. 
     
     
         4 . The device of  claim 2 , wherein the transformer module comprises regulator circuitry coupled to the transformer circuitry. 
     
     
         5 . The device of  claim 4 , wherein a regulator circuitry output is coupled to the detector circuitry and the output controller. 
     
     
         6 . The device of  claim 4 , wherein the battery charging circuitry is coupled to the regulator circuitry. 
     
     
         7 . The device of  claim 1 , wherein the input signal is an alternating current (AC) signal. 
     
     
         8 . The device of  claim 1 , wherein the device output is an alternating current (AC) signal. 
     
     
         9 . The device of  claim 1 , wherein the device output is a direct current (DC) signal. 
     
     
         10 . A device comprising:
 transformer circuitry, wherein the transformer circuitry receives an input signal;   regulator circuitry coupled to the transformer circuitry;   a battery module coupled to the regulator circuitry, the battery module comprising battery charging circuitry coupled to a battery; and   an output controller, wherein a first input of the output controller is coupled to a power output of the regulator circuitry, wherein a second input of the output controller is coupled to a battery output of the battery module, wherein the output controller automatically switches one of the power output and the battery output as a device output according to a state of the input signal.   
     
     
         11 . The device of  claim 10 , comprising a detector coupled to the regulator circuitry and the output controller, wherein the detector provides a control signal to the controller in response to a detected state of the input signal. 
     
     
         12 . The device of  claim 10 , wherein the transformer circuitry comprises a step-down transformer that reduces a voltage of the input signal. 
     
     
         13 . The device of  claim 10 , wherein the input signal is an alternating current (AC) signal. 
     
     
         14 . The device of  claim 10 , wherein the device output is an alternating current (AC) signal. 
     
     
         15 . The device of  claim 10 , wherein the device output is a direct current (DC) signal. 
     
     
         16 . A method comprising:
 receiving an input signal at a device;   generating a first output signal by transforming the input signal;   charging a battery of the device with the first output signal;   providing a second output signal that is an output of the battery;   detecting a state of the input signal; and   automatically controlling an output of the device to be one of the first output signal and the second output signal according to the state of the input signal.   
     
     
         17 . The method of  claim 16 , wherein automatically controlling comprises coupling the first output signal to the output of the device when the state of the input signal is present. 
     
     
         18 . The method of  claim 17 , wherein the charging of the battery occurs when the state of the input signal is present. 
     
     
         19 . The method of  claim 17 , wherein automatically controlling comprises coupling the second output signal to the output of the device when the state of the input signal is absent. 
     
     
         20 . The method of  claim 16 , wherein the transforming comprises reducing a voltage of the input signal. 
     
     
         21 . The method of  claim 20 , wherein the transforming comprises regulating the voltage of the input signal. 
     
     
         22 . The method of  claim 16 , wherein the input signal is an alternating current (AC) signal, and the output of the device is one of an alternating current (AC) signal and a direct current (DC) signal.