Circuit for indicating power level over a communication interface

Abstract

A circuit is provided. The circuit includes a control circuit, a voltage sensor coupled to the control circuit, an indicator signal coupled to the control circuit, and at least one current source. The control circuit, responsive to the voltage sensor, is configured to detect a first classification voltage within a classification voltage range defined by a lower classification voltage limit and upper classification voltage limit, detect, after detecting the first classification voltage, an indexing voltage outside of the classification voltage range, and detect a second classification voltage within the classification voltage range. The at least one current source provides a first and second predetermined classification current responsive to the first classification voltage and the second classification voltage, respectively. The control circuit is configured to set the indicator signal to a first predetermined state indicating a power type based on the detected first classification voltage, indexing voltage and second classification voltage.

We claim: 
     
         1 . A circuit, comprising:
 a control circuit;   a voltage sensor coupled to the control circuit;   an indicator signal coupled to the control circuit; and   at least one current source coupled to the control circuit, wherein the control circuit is configured to control the at least one current source to provide a first predetermined classification current responsive to the detected first classification voltage and a second predetermined classification current responsive to the detected second classification voltage,   wherein the second predetermined classification current represents an adjacent valid classification value to the first predetermined classification current,   wherein the control circuit, responsive to the voltage sensor, is configured to:
 detect a first classification voltage within a classification voltage range defined by a lower classification voltage limit and upper classification voltage limit; 
 detect, after detecting the first classification voltage, an indexing voltage outside of the classification voltage range; and 
 detect, after detecting the indexing voltage, a second classification voltage within the classification voltage range, wherein the control circuit is further configured to set the indicator signal to a first predetermined state indicating a power type based on the detected first classification voltage, indexing voltage and second classification voltage. 
   
     
     
         2 . The circuit of  claim 1 , wherein the second predetermined classification current represents a circularly adjacent valid classification value to the first predetermined classification current, wherein when the first predetermined classification current does not represent a valid classification value of four, the second predetermined classification current represents the next higher valid classification value than the first predetermined classification value, wherein when the first predetermined classification current represents a valid classification value of four, the second predetermined classification current represents a valid classification value of one. 
     
     
         3 . The circuit of  claim 1 , wherein the second predetermined classification current represents a circularly adjacent valid classification value to the first predetermined classification current, wherein when the first predetermined classification current does not represent a valid classification value of one, the second predetermined classification current represents the next lower valid classification value than the first predetermined classification value, wherein when the first predetermined classification current represents a valid classification value of one, the second predetermined classification current represents a valid classification value of four. 
     
     
         4 . A circuit, comprising:
 a control circuit;   a voltage sensor coupled to the control circuit;   a current source coupled to the control circuit; and   an indicator signal coupled to the control circuit,   wherein the control circuit, responsive to the voltage sensor, is configured to:
 detect a first classification voltage within a classification voltage range defined by a lower classification voltage limit and upper classification voltage limit; 
 generate a first classification current, by the current source, in response to detecting the first classification voltage; 
 determine if an indexing voltage is detected, wherein the indexing voltage is outside of the classification voltage range;
 if the indexing voltage is not detected, then set an indicator signal to a low power state based on an operating voltage; and 
 if the indexing voltage is detected, then:
 detect a second classification voltage within the classification voltage range, and 
 generate a second classification current, by the current source, in response to detecting the second classification voltage, 
 
 
   wherein the second classification current represents an adjacent valid classification value to the first classification current.   
     
     
         5 . The circuit of  claim 4 , wherein the second classification current represents a circularly adjacent valid classification value to the first classification current, wherein when the first classification current does not represent a valid classification value of four, the second classification current represents the next higher valid classification value than the first classification value, wherein when the first classification current represents a valid classification value of four, the second classification current represents a valid classification value of one. 
     
     
         6 . The circuit of  claim 4 , wherein the second classification current represents a circularly adjacent valid classification value to the first classification current, wherein when the first classification current does not represent a valid classification value of one, the second classification current represents the next lower valid classification value than the first classification value, wherein when the first classification current represents a valid classification value of one, the second classification current represents a valid classification value of four. 
     
     
         7 . An Ethernet device, comprising:
 a control circuit;   a voltage sensor coupled to the control circuit;   a current source coupled to the control circuit; and   an indicator signal coupled to the control circuit,   wherein the control circuit, responsive to the voltage sensor, is configured to:
 detect a first classification voltage within a classification voltage range defined by a lower classification voltage limit and upper classification voltage limit; 
 generate a first classification current, by the current source, in response to detecting the first classification voltage; 
 determine if an indexing voltage is detected, wherein the indexing voltage is outside of the classification voltage range;
 if the indexing voltage is not detected, then set an indicator signal to a low power state based on an operating voltage; and 
 if the indexing voltage is detected, then:
 detect a second classification voltage within the classification voltage range, and 
 generate a second classification current, by the current source, in response to detecting the second classification voltage, 
 
 
   wherein the second classification current represents an adjacent valid classification value to the first classification current.   
     
     
         8 . The Ethernet device of  claim 7 , wherein the second classification current represents a circularly adjacent valid classification value to the first classification current, wherein when the first classification current does not represent a valid classification value of four, the second classification current represents the next higher valid classification value than the first classification value, wherein when the first classification current represents a valid classification value of four, the second classification current represents a valid classification value of one. 
     
     
         9 . The Ethernet device of  claim 7 , wherein the second classification current represents a circularly adjacent valid classification value to the first classification current, wherein when the first classification current does not represent a valid classification value of one, the second classification current represents the next lower valid classification value than the first classification value, wherein when the first classification current represents a valid classification value of one, the second classification current represents a valid classification value of four.