Hard disk drive (HDD) electrical over voltage stress (EOS) systems and methods

Abstract

The present invention relates to a hard disk drive system having overvoltage protection circuits for various types of overvoltage conditions. For example, the system comprises one or more hard disk drive integrated circuit chips residing on a board and a hard disk drive power plug receptacle residing on the board having two different value power supply ports associated therewith. The receptacle is operable to receive a power plug therein, wherein when the power plug is inserted therein in a proper orientation the two different value voltages are properly supplied to the one or more hard disk drive integrated circuit chips, and wherein when the power plug is inserted therein in an improper orientation the two different value voltages are switched with respect to their intended values. The system comprises a reverse power plug orientation protection circuit coupled between the hard disk drive power plug receptacle and at least one of the one or more hard disk drive integrated circuit chips. The protection circuit is operable to detect an improper orientation of the power plug when inserted into the hard disk drive power plug receptacle and reduce a larger of the two different voltage values, thereby preventing an electrical over voltage stress of the at least one hard disk drive integrated circuit chip.

What is claimed is:  
     
         1 . A memory storage device circuit board such as a hard disk drive circuit board, comprising: 
 one or more hard disk drive integrated circuit chips residing on the board;    a hard disk drive power plug receptacle residing on the board having two different value power supply ports associated therewith and operable to receive a power plug therein, wherein when the power plug is inserted therein in a proper orientation the two different value voltages are properly supplied to the one or more hard disk drive integrated circuit chips, and wherein when the power plug is inserted therein in an improper orientation the two different value voltages are switched with respect to their intended values; and    a reverse power plug orientation protection circuit coupled between the hard disk drive power plug receptacle and at least one of the one or more hard disk drive integrated circuit chips, wherein the reverse power plug is operable to detect an improper orientation of the power plug when inserted into the hard disk drive power plug receptacle and reduce a larger of the two different voltage values, thereby preventing an electrical over voltage stress of the at least one hard disk drive integrated circuit chip.    
     
     
         2 . The memory storage device circuit board of  claim 1 , wherein the reverse power plug orientation protection circuit comprises a variable resistor circuit having a first terminal coupled to a portion of the power plug receptacle associated with a lower of the two different voltage values when the power plug is properly inserted therein, and having a second terminal coupled to a trace on the board for transmitting the lower voltage value to at least one of the hard disk drive integrated circuit chips, and wherein when the power plug is inserted properly into the power plug receptacle, the variable resistor approximates a short circuit, thereby substantially transmitting the lower voltage value to the at least one integrated circuit chip, and wherein when the power plug is inserted in an improper orientation, the variable resistor is substantially resistive, causing the larger voltage value to experience a voltage drop thereacross, thereby reducing a voltage value at the trace and preventing an electrical over voltage stress of the at least one hard disk drive integrated circuit chip.  
     
     
         3 . The memory storage device circuit board of  claim 2 , wherein a resistance of the variable resistor circuit is controlled by a voltage value at another portion of the power plug receptacle associated with the larger of the two different voltage values when the power plug is properly inserted therein.  
     
     
         4 . The memory storage device circuit board of  claim 2 , wherein the variable resistor circuit comprises a transistor having a control terminal coupled to another portion of the power plug receptacle associated with the larger of the two different voltage values when the power plug is properly inserted therein.  
     
     
         5 . The memory storage device circuit board of  claim 4 , wherein the transistor comprises an NMOS transistor, and wherein the control terminal comprises a gate terminal thereof.  
     
     
         6 . The memory storage device circuit board of  claim 1 , wherein the hard disk driver power plug receptacle comprises a four pin adapter, wherein a first pin is intended to accommodate a first supply voltage value, a second and third pin are intended to accommodate a circuit ground potential value, and a fourth pin is intended to accommodate a second supply voltage value, wherein the first supply voltage value is greater than the second supply voltage value.  
     
     
         7 . The memory storage device circuit board of  claim 6 , wherein the reverse power plug orientation protection circuit comprises: 
 a sensing circuit operable to detect an improper orientation of the power plug in the power plug receptacle; and    a voltage reduction circuit associated with the fourth pin of the four pin adapter, and operable to reduce a voltage associated with the fourth pin when the sensing circuit detects the improper power plug orientation.    
     
     
         8 . The memory storage device circuit board of  claim 6 , wherein the reverse power plug orientation protection circuit comprises a variable resistance circuit, and is operable to exhibit substantially no resistance when the power plug is inserted into the four pin adapter in the proper orientation, and wherein the variable resistance circuit is operable to exhibit a substantial resistance when the power plug is inserted into the four pin adapter in the improper orientation.  
     
     
         9 . The memory storage device circuit board of  claim 8 , wherein the variable resistance circuit comprises a transistor having a control terminal coupled to the first pin of the four pin adapter, wherein when the power plug is inserted into the four pin adapter in the proper orientation, the transistor is substantially conducting and behaving approximately as a short circuit, and wherein when the power plug is inserted into the four pin adapter in the improper orientation, the transistor is partially conducting and exhibits a substantial resistance and therefore a substantial voltage drop thereacross.  
     
     
         10 . An overvoltage protection circuit, comprising: 
 one or more hard disk drive integrated circuit chips residing on a board;    a first voltage supply potential for supplying power to at least one of the one or more hard disk drive integrated circuit chips;    a second voltage supply potential having an intended value which is less than the first voltage supply potential, the second voltage supply potential for supplying power to at least one of the one or more hard disk drive integrated circuit chips;    a voltage detection circuit operable to detect a value of the second voltage supply potential; and    a voltage reduction circuit operably coupled to the voltage detection circuit,    wherein the voltage detection circuit is operable to activate the voltage reduction circuit when the second voltage supply potential exceeds a predetermined threshold, and wherein the voltage reduction circuit is operable to reduce a value of the second supply potential when activated by the voltage detection circuit.    
     
     
         11 . The overvoltage protection circuit of  claim 10 , wherein the voltage reduction circuit is further operably coupled to the first voltage supply potential.  
     
     
         12 . The overvoltage protection circuit of  claim 10 , wherein the voltage detection circuit comprises a zener diode which is reverse biased and conducts substantially no current when the second voltage supply potential is less than the predetermined threshold.  
     
     
         13 . The overvoltage protection circuit of  claim 10 , wherein the voltage detection circuit further comprises a resistor coupled in series with the zener diode, wherein when the zener diode has a reverse bias voltage thereacross which exceeds the predetermined threshold, the zener diode breaks down and conducts current therethrough, thereby generating a voltage across the resistor, and wherein when the voltage across the resistor exceeds a predetermined level, the voltage activates the voltage reduction circuit.  
     
     
         14 . The overvoltage protection circuit of  claim 13 , further comprising a first transistor coupled between the second voltage supply potential and a trace which transmits the second voltage supply potential to at least one of the one or more hard disk drive integrated circuit chips, and wherein the first transistor has a control terminal coupled to the first voltage supply potential, and wherein the voltage reduction circuit comprises a second transistor coupled to the control terminal of the first transistor and having a control terminal coupled to the resistor of the voltage detection circuit, wherein when the voltage across the resistor in the voltage detection circuit exceeds the predetermined level, the second transistor turns on and lowers a voltage of the control terminal of the first transistor, thereby reducing a conduction of the first transistor and reducing a voltage value provided by the second voltage supply potential to the trace.  
     
     
         15 . An overvoltage protection circuit for a hard disk drive circuit board, comprising: 
 one or more hard disk drive integrated circuit chips residing on the board;    a first voltage supply potential for supplying power to at least one of the hard disk drive integrated circuit chips;    a second voltage supply potential for supplying power to at least one of the hard disk drive integrated circuit chips, wherein the second voltage supply potential has an intended value which is less than the first voltage supply potential;    a first transistor coupled between the second voltage supply potential and a trace for transmitting the second voltage supply potential to the at least one hard disk drive integrated circuit chip, and a control terminal coupled to the first voltage supply potential through a first resistor, wherein when the first transistor is substantially conducting, the second voltage supply potential is transmitted substantially to the trace, and wherein when the first transistor is not conducting substantially, a substantial voltage drop exists thereacross and a voltage potential transmitted to the trace is less than the second voltage supply potential;    a zener diode coupled to the first transistor and operable to be reverse biased and nonconducting when a value of the second voltage supply potential is less than a predetermined level, and wherein the zener diode is operable to break down and conduct current therethrough when the value of the second voltage supply potential is greater than or equal to the predetermined level;    a second resistor coupled in series with the zener diode and operable to exhibit a voltage thereacross when the zener diode is conducting current; and    a second transistor coupled between the control terminal of the first transistor and one terminal of the second resistor, and a control terminal coupled to the other terminal of the second resistor, and wherein when the zener diode conducts current due to the second voltage supply potential exceeding the predetermined level, a voltage develops across the second resistor and causes the second transistor to conduct, and wherein the conduction of the second transistor causes a conduction of the first transistor to be reduced, thereby reducing the voltage at the trace.    
     
     
         16 . An overvoltage protection circuit, comprising: 
 one or more hard disk drive integrated circuit chips residing on a board;    a first voltage supply potential for supplying power to at least one of the one or more hard disk drive integrated circuit chips;    a second voltage supply potential having an intended value which is less than the first voltage supply potential, the second voltage supply potential for supplying power to at least one of the one or more hard disk drive integrated circuit chips;    a voltage detection circuit operable to detect a value of the first voltage supply potential; and    a voltage reduction circuit operably coupled to the voltage detection circuit,    wherein the voltage detection circuit is operable to activate the voltage reduction circuit when the second voltage supply potential exceeds a predetermined threshold, and wherein the voltage reduction circuit is operable to reduce a value of the first supply potential when activated by the voltage detection circuit.    
     
     
         17 . The overvoltage protection circuit of  claim 16 , wherein the voltage detection circuit comprises a zener diode which is reverse biased and conducts substantially no current when the first voltage supply potential is less than the predetermined threshold.  
     
     
         18 . The overvoltage protection circuit of  claim 16 , wherein the voltage detection circuit further comprises a resistor coupled in series with the zener diode, wherein when the zener diode has a reverse bias voltage thereacross which exceeds the predetermined threshold, the zener diode breaks down and conducts current therethrough, thereby generating a voltage across the resistor, and wherein when the voltage across the resistor exceeds a predetermined level, the voltage activates the voltage reduction circuit.  
     
     
         19 . The overvoltage protection circuit of  claim 18 , wherein the voltage reduction circuit comprises: 
 a first transistor coupled between the first voltage supply potential and a trace which transmits the first voltage supply potential to at least one of the one or more hard disk drive integrated circuit chips; and    a second transistor coupled to a control terminal of the first transistor and having a control terminal coupled to the resistor of the voltage detection circuit,    wherein when the voltage across the resistor in the voltage detection circuit exceeds the predetermined level, the second transistor turns on and lowers a voltage of the control terminal of the first transistor, thereby reducing a conduction of the first transistor and reducing a voltage value provided by the first voltage supply potential to the trace.    
     
     
         20 . The overvoltage protection circuit of  claim 16 , further comprising a reset circuit coupled to the voltage detection circuit, wherein the reset circuit is operable to activate a reset signal to a controller circuit associated with the board to reset the one or more circuit components on the board when voltage detection circuit detects a first voltage supply potential which exceeds the predetermined threshold.  
     
     
         21 . The overvoltage protection circuit of  claim 20 , wherein the reset circuit comprises a transistor having a control terminal coupled to the voltage detection circuit, wherein an activation of the voltage detection circuit due to an overvoltage detection causes the transistor to change conduction states, thereby changing a voltage state on an output of the transistor which serves as the reset signal.  
     
     
         22 . The overvoltage protection circuit of  claim 16 , wherein the voltage reduction circuit comprises: 
 a first transistor having a backgate diode associated therewith; and    a second transistor having a backgate diode associated therewith,    wherein the first and second transistor are coupled together in series in such a manner that the backgate diodes are oriented with respect to one another in a back-to-back fashion, thereby preventing conduction therethrough under overvoltage conditions when the first and second transistors are biased in a substantially resistive condition based on an activation signal from the voltage detection circuit.    
     
     
         23 . The overvoltage protection circuit of  claim 22 , wherein a back-to-back orientation of the backgate diodes comprises a configuration where a cathode terminal of the backgate diodes are coupled together or a configuration where an anode terminal of the backgate diodes are coupled together.  
     
     
         24 . An overvoltage protection circuit for a hard disk drive circuit board, comprising: 
 one or more hard disk drive integrated circuit chips residing on the board;    a first voltage supply potential for supplying power to at least one of the hard disk drive integrated circuit chips;    a second voltage supply potential for supplying power to at least one of the hard disk drive integrated circuit chips, wherein the second voltage supply potential has an intended value which is less than the first voltage supply potential;    a first transistor coupled between the first voltage supply potential and a trace for transmitting the first voltage supply potential to the at least one hard disk drive integrated circuit chip, wherein when the first transistor is substantially conducting, the first voltage supply potential is transmitted substantially to the trace, and wherein when the first transistor is not conducting substantially, a substantial voltage drop exists thereacross and a voltage potential transmitted to the trace is less than the first voltage supply potential;    a zener diode coupled to the first transistor and operable to be reverse biased and nonconducting when a value of the first voltage supply potential is less than a predetermined level, and wherein the zener diode is operable to break down and conduct current therethrough when the value of the first voltage supply potential is greater than or equal to the predetermined level;    a second resistor coupled in series with the zener diode and operable to exhibit a voltage thereacross when the zener diode is conducting current; and    a second transistor coupled between the control terminal of the first transistor and one terminal of the second resistor, and a control terminal coupled to the other terminal of the second resistor, wherein when the zener diode conducts current due to the first voltage supply potential exceeding the predetermined level, a voltage develops across the second resistor and causes the second transistor to conduct, and wherein the conduction of the second transistor causes a conduction of the first transistor to be reduced, thereby reducing the voltage at the trace.    
     
     
         25 . The overvoltage protection circuit of  claim 24 , further comprising a third transistor coupled in series between the first transistor and the zener diode, and wherein the first and third transistors have backgate diodes associated therewith in which the backgate diodes are oriented in a back-to-back configuration, thereby preventing conduction therethrough when the first and third transistors are biased in a substantially resistive condition based on an activation of the second transistor when an overvoltage condition is detected.