Overvoltage and surge protection circuit in a hard disk drive

• US 5,930,096 A
• Filed: 06/03/1998
• Issued: 07/27/1999
• Est. Priority Date: 06/03/1997
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Jae-June
• Primary Examiner(s): Medley, Sally C.
• Application Number:
  US09/089,664
• Time in Patent Office: 419 Days
• Field of Search: 361/18, 361/56-58, 361/77.82, 361/84, 361/91, 307/43, 307/44, 307/64, 307/75, 307/86
• US Class Current: 358/1.15
• CPC Class Codes: H02H 11/006 in case of too high or too low voltage

Abstract

An overvoltage and surge protection circuit for a hard disk drive is provided. The overvoltage and surge protection circuit is intended for protecting an interior circuit part from a surge voltage caused by an overvoltage generated due to wrong insertion of first and second power supply voltages, and an external condition, in a hard disk drive which receive the first power supply voltage as an operational voltage of an interior circuit device and the second power supply voltage as a device driving voltage. The overvoltage and surge protection circuit includes an overvoltage protection circuit having a first and second power supply input terminals for receiving the first and second power supply voltages, respectively, and a surge protection circuit. The overvoltage protection circuit lowers the level of the second power supply voltage below the level of the first power supply voltage, using the first power supply voltage applied through the second power supply input termninal, and applies the lowered second power supply voltage to a load of the interior circuit device, when the second power supply voltage is applied through the first power supply input terminal. The surge protection circuit lowered the surge voltage to a constant voltage below the first power supply voltage, and applied the constant voltage to the load of the interior circuit device, when the surge voltage is applied through the first power supply input terminal and the overvoltage protection circuit.

Claims

1. An overvoltage and surge protection circuit for protecting an interior circuit part from a surge voltage caused by an overvoltage generated due to wrong insertion of first and second power supply voltages, and an external condition, in a hard disk drive which receive the first power supply voltage as an operational voltage of an interior circuit device and the second power supply voltage as a device driving voltage, comprising:

an overvoltage protection circuit having a first and second power supply input terminals for receiving the first and second power supply voltages, respectively, for lowering the level of the second power supply voltage below the level of the first power supply voltage, using the first power supply voltage applied through the second power supply input terminal, and applying the lowered second power supply voltage to a load of the interior circuit device, when the second power supply voltage is applied through the first power supply input terminal; and

a surge protection circuit for lowering the surge voltage to a constant voltage below the first power supply voltage, and applying the constant voltage to the load of the interior circuit device, when the surge voltage is applied through the first power supply input terminal and the overvoltage protection circuit.

2. The overvoltage and surge protection circuit as set forth in claim 1, wherein said overvoltage protection circuit comprises:

a transistor having a drain connected to said first power supply input terminal, a source connected to said surge protection circuit and a gate connected to said second power supply input terminal via a first resistor; and

a second resistor connected between said gate and a ground terminal.

3. The overvoltage and surge protection circuit as set forth in claim 2, wherein said surge protection circuit comprises a zener diode and a third resistor connected in series between said source of said transistor and said ground terminal.

4. The overvoltage and surge protection circuit as set forth in claim 3, wherein said transistor comprises a N-channel MOS field effect transistor.

5. The overvoltage and surge protection circuit as set forth in claim 2, wherein said transistor comprises a N-channel MOS field effect transistor.

6. The overvoltage and surge protection circuit as set forth in claim 1, wherein said surge protection circuit comprises a zener diode and a resistor connected in series between said overvoltage protection circuit and a ground terminal.

7. An overvoltage and surge protection circuit for a hard disk drive, comprising:

a first voltage source input terminal connectable to a first direct current voltage;

a second voltage source input terminal being connectable to a second direct current voltage, said second direct current voltage being higher than said first direct current voltage;

a transistor having a drain connected to said first voltage source input terminal, a source, and a gate connected to said second voltage source input terminal via a first resistor;

a second resistor connected between said gate and a ground terminal; and

a zener diode and a third resistor connected in series between said source of said transistor and said ground terminal.

8. The overvoltage and surge protection circuit as set forth in claim 7, wherein said transistor comprises a N-channel MOS field effect transistor.

9. An overvoltage and surge protection circuit for a hard disk drive, comprising:

a first voltage source input terminal connectable to a first direct current voltage;

a second voltage source input terminal being connectable to a second direct current voltage, said second direct current voltage being higher than said first direct current voltage;

a surge protection circuit connected to a load; and

an overvoltage protection circuit having a first terminal connected to said first voltage source input terminal and a second terminal connected to said second voltage source input terminal, said overvoltage protection circuit being enabled to connect said surge protection circuit to said first voltage source input terminal when second voltage source input terminal is connected to said second direct current voltage, said overvoltage protection circuit being disabled from connecting said surge protection circuit to said first voltage source input terminal if said second voltage source input terminal is connected to said first direct current voltage.

10. The overvoltage and surge protection circuit as set forth in claim 9, wherein said overvoltage protection circuit comprises:

a transistor having a drain connected to said first voltage source input terminal, a source connected to said surge protection circuit and a gate connected to said second voltage source input terminal via a first resistor; and

a second resistor connected between said gate and a ground terminal.

11. The overvoltage and surge protection circuit as set forth in claim 10, wherein said surge protection circuit comprises a zener diode and a third resistor connected in series between said source of said transitor and said ground terminal.

12. The overvoltage and surge protection circuit as set forth in claim 11, wherein said transistor comprises a N-channel MOS field effect transistor.

13. The overvoltage and surge protection circuit as set forth in claim 9, wherein said surge protection circuit comprises a zener diode and a resistor connected in series between said overvoltage protection circuit and a ground terminal.

14. The overvoltage and surge protection circuit as set forth in claim 13, wherein said transistor comprises a N-channel MOS field effect transistor.