Multi-voltage charging apparatus

Abstract

A charging apparatus includes a charging terminal, a ground terminal, and a coupling circuit coupled to the charging terminal. The coupling circuit is configured to sense a charging voltage applied to the charging terminal and to selectively couple the charging terminal to a first charging node in response to a first voltage being applied to the charging terminal, and to selectively couple the charging terminal to a second charging node in response to a second voltage being applied to the voltage sensing terminal, the second voltage being different from the first voltage.

1 . A charging apparatus, comprising:
 a charging terminal;   a ground terminal; and   a coupling circuit coupled to the charging terminal, wherein the coupling circuit is configured to sense a charging voltage applied to the charging terminal and to selectively couple the charging terminal to a first charging node in response to a first voltage being applied to the charging terminal, and to selectively couple the charging terminal to a second charging node in response to a second voltage being applied to the voltage sensing terminal, the second voltage being different from the first voltage.   
     
     
         2 . The charging apparatus of  claim 1 , wherein the coupling circuit comprises:
 a voltage regulator configured to supply a third voltage;   a microcontroller;   first, second, third and fourth transistor switches, each of the first, second, third and fourth transistor switches comprising a control terminal coupled to the charging node, an output terminal coupled to the microcontroller, and an input terminal coupled to the voltage regulator;   a first relay coupled to the microcontroller, the charging terminal, and the first charging node; and   a second relay coupled to the microcontroller, the charging terminal, and the second charging node;   wherein the microcontroller is configured to cause the first relay to controllably couple the charging terminal to the first charging node and the second relay to controllably couple the charging terminal to the second charging node in response to signals output by the first, second, third and fourth transistor switches.   
     
     
         3 . The charging apparatus of  claim 2 ,
 wherein the first, second, third and fourth transistor switches comprise normally off enhancement mode MOSFETs, wherein the first, second, third and fourth transistor switches have respective first, second, third and fourth different turn-on voltages.   
     
     
         4 . The charging apparatus of  claim 2 , wherein the relays comprise optically triggered relays that isolate the charging terminal and the first and second charging nodes from the microcontroller. 
     
     
         5 . The charging apparatus of  claim 4 , wherein each relay comprises a photodiode and a photosensitive relay circuit. 
     
     
         6 . The charging apparatus of  claim 5 , wherein, for each relay, energizing the photodiode causes the photosensitive relay circuit to conduct. 
     
     
         7 . The charging apparatus of  claim 1 , further comprising:
 a first indicator lamp coupled between the charging terminal and the first charging node, wherein the first indicator lamp is activated in response to coupling the charging terminal to the first charging node.   
     
     
         8 . The charging apparatus of  claim 7 , further comprising:
 a second indicator lamp coupled between the charging terminal and the second charging node, wherein the second indicator lamp is activated in response to coupling the charging terminal to the second charging node.   
     
     
         9 . The charging apparatus of  claim 1 , wherein the first charging node comprises a 12 volt charging node. 
     
     
         10 . The charging apparatus of  claim 9 , wherein the second charging node comprises a 24 volt charging node. 
     
     
         11 . A method comprising:
 sensing a charging voltage applied to a charging terminal of a charging apparatus;   in response to a first voltage being applied to the charging terminal, selectively couple the charging terminal to a first charging node of the charging apparatus; and   in response to a second voltage being applied to the voltage sensing terminal, selectively couple the charging terminal to a second charging node of the charging apparatus.   
     
     
         12 . The method of  claim 11 , wherein the coupling circuit further comprises:
 a voltage regulator configured to supply a third voltage;   a microcontroller;   first, second, third and fourth transistor switches, each of the first, second, third and fourth transistor switches comprising a control terminal coupled to the charging node, an output terminal coupled to the microcontroller, and an input terminal coupled to the voltage regulator;   a first relay coupled to the microcontroller, the charging terminal, and the first charging node; and   a second relay coupled to the microcontroller, the charging terminal, and the second charging node, the method further comprising:   causing the first relay to controllably couple the charging terminal to the first charging node and the second relay to controllably couple the charging terminal to the second charging node in response to signals output by the first, second, third and fourth transistor switches.   
     
     
         13 . The method of  claim 12 , wherein the first, second, third and fourth transistor switches comprise normally off enhancement mode MOSFETs, wherein the first, second, third and fourth transistor switches have respective first, second, third and fourth different turn-on voltages. 
     
     
         14 . The method of  claim 12 , wherein the relays comprise optically triggered relays isolating the charging terminal and the first and second charging nodes from the microcontroller. 
     
     
         15 . The method of  claim 14 , wherein each relay comprises a photodiode and a photosensitive relay circuit. 
     
     
         16 . The method of  claim 15 , further comprising:
 selectively energizing the photodiode of each relay to cause the photosensitive relay circuit to conduct.   
     
     
         17 . The method of  claim 11 , further comprising:
 activating a first indicator lamp coupled between the charging terminal and the first charging node, in response to coupling the charging terminal to the first charging node.   
     
     
         18 . The method of  claim 17 , further comprising:
 activating a second indicator lamp coupled between the charging terminal and the second charging node in response to coupling the charging terminal to the second charging node.   
     
     
         19 . The method of  claim 11 , wherein the first charging node comprises a 12 volt charging node. 
     
     
         20 . The method of  claim 19 , wherein the second charging node comprises a 24 volt charging node.