System and method for high voltage protection of powered devices

Abstract

An integrated circuit includes a rectifier circuit, at least one low power element, and a power protection element. The rectifier circuit includes two inputs to receive an input power supply and includes two outputs to provide a rectified power supply related to the input power supply. The low-power circuit element is coupled between the two outputs. The power protection element is coupled between the two output terminals. In a first mode of operation, the power protection element presents a high impedance to the two output terminals. In a second mode of operation, the power protection element has a first power protection characteristic. In a third mode of operation, the power protection element has a second power protection characteristic. The power protection element is adapted to shut down the low-power circuit element when in the third mode of operation.

1 . An integrated circuit comprising: 
 a rectifier circuit having two inputs to receive an input power supply and having two outputs to provide a rectified power supply related to the input power supply;    at least one low-power circuit element coupled between the two outputs; and    a power protection element coupled between the two output terminals, wherein, in a first mode of operation, the power protection element presents a high impedance to the two output terminals, in a second mode of operation, the power protection element has a first power protection characteristic, and in a third mode of operation, the power protection element has a second power protection characteristic, the power protection element to shut down the at least one low-power circuit element when in the third mode of operation.    
   
   
       2 . The integrated circuit of  claim 1 , wherein the power protection element comprises an over-voltage threshold component to detect an over-voltage condition and a switch coupled to the over-voltage threshold component to clamp the rectified power supply to a voltage level that is below a threshold voltage level.  
   
   
       3 . The integrated circuit of  claim 1 , wherein the power protection element comprises two switches adapted to activate asynchronously in response to a signal to clamp the rectified power supply to a reduced voltage level.  
   
   
       4 . The integrated circuit of  claim 1 , wherein the power protection element comprises a silicon controlled rectifier.  
   
   
       5 . The integrated circuit of  claim 1 , wherein the power protection element further comprises active logic to generate a fault protection signal provided to the at least one low-power circuit element when in the third mode of operation.  
   
   
       6 . The integrated circuit of  claim 5 , wherein the fault protection signal comprises a shut down signal to deactivate the at least one low-power circuit element.  
   
   
       7 . The integrated circuit of  claim 1 , wherein the power protection element is at a higher voltage in the second mode of operation than in the third mode of operation.  
   
   
       8 . The integrated circuit of  claim 7 , wherein in the second mode of operation, the higher voltage is greater than 55 volts and wherein the power protection element has a current level less than one Ampere.  
   
   
       9 . The integrated circuit of  claim 7 , wherein in the third mode of operation, the power protection element has a voltage level less than ten volts and a current level greater than half an Ampere.  
   
   
       10 . The integrated circuit of  claim 7 , wherein the power protection element changes from the second mode of operation to the first mode of operation after a current level of the power protection element falls below a threshold current level.  
   
   
       11 . The integrated circuit of  claim 1 , wherein the second power protection characteristic comprises a lower impedance than the first power protection characteristic.  
   
   
       12 . A method comprising: 
 receiving an input voltage supply at a pair of terminals;    detecting an over-voltage condition related to the input voltage supply using an over-voltage protection element; and    concurrently shunting the input voltage supply between the pair of terminals and generating a shut off signal to associated circuitry in response to the over-voltage condition using the over-voltage protection element.    
   
   
       13 . The method of  claim 12 , wherein detecting an over-voltage condition comprises: 
 detecting a voltage at a silicon controlled rectifier of an integrated circuit, the integrated circuit having at least one low-voltage component; and    maintaining a first transistor and a second transistor in an off state when the voltage is less than a voltage protection threshold.    
   
   
       14 . The method of  claim 13 , wherein shunting the input voltage supply comprises: 
 activating the first transistor and the second transistor to shunt the voltage to a lower voltage level when the voltage exceeds the voltage protection threshold; and    generating a fault protection signal to shut off power to the at least one low-voltage component.    
   
   
       15 . The method of  claim 14 , wherein activating the first transistor and the second transistor comprises activating the first transistor before activating the second transistor.  
   
   
       16 . The method of  claim 12 , wherein detecting the over-voltage condition comprises: 
 receiving an input voltage from a powered network at an integrated circuit including the over-voltage protection element;    rectifying the input voltage to produce a rectified voltage; and    detecting a voltage level of the rectified voltage.    
   
   
       17 . An integrated circuit comprising: 
 input terminals to receive an input power supply;    at least one low-power circuit element coupled between the input terminals; and    a power protection element coupled between the input terminals to detect a power characteristic of the input power supply, the power protection element to shunt excess power between the input terminals and to shut off power to the at least one low-power circuit element when the power characteristic exceeds a threshold power level.    
   
   
       18 . The integrated circuit of  claim 17 , wherein the power characteristic comprises a voltage level in excess of a threshold voltage level.  
   
   
       19 . The integrated circuit of  claim 17 , wherein the power characteristic comprises a current level that is greater than a threshold current level.  
   
   
       20 . The integrated circuit of  claim 17 , wherein the power protection element comprises a silicon controlled rectifier circuit.  
   
   
       21 . The integrated circuit of  claim 17 , wherein the input terminals comprise a first power supply terminal and a second power supply terminal and wherein the power protection element comprises: 
 a resistor having a first terminal coupled to the second power supply terminal, and a second terminal;    a diode circuit having an anode terminal coupled to the second terminal of the resistor and a cathode terminal coupled to the first power supply terminal; and    a transistor having a first terminal coupled to the first power supply terminal, a second terminal coupled to the second power supply terminal, and a control terminal coupled to the second terminal of the resistor, the transistor providing a current path between the first power supply terminal and the second power supply terminal when active.    
   
   
       22 . The integrated circuit of  claim 17 , wherein the input terminals are coupled to a powered network.  
   
   
       23 . A method comprising: 
 receiving an input power supply at a pair of terminals, the pair of terminals including a first terminal and a second terminal;    detecting a power level of the input power supply using a power protection element of an integrated circuit, the integrated circuit having at least one low-power component;    activating the power protection element to shunt the input power supply between the first terminal and the second terminal when the power level exceeds a threshold power level; and    substantially reducing a power supply to the at least one low-power component when the power level exceeds the threshold power level.    
   
   
       24 . The method of  claim 23 , wherein the power protection element comprises a first transistor and a second transistor, the first transistor and the second transistor coupled between the first terminal and the second terminal, the method further comprising: 
 maintaining the first transistor and the second transistor in an off state when the power level is less than the threshold power level.    
   
   
       25 . The method of  claim 24 , wherein activating the power protection element comprises activating the first transistor before activating the second transistor.