POWER-FAILURE PROTECTION CIRCUIT FOR NON-VOLATILE SEMICONDUCTOR STORAGE DEVICES AND METHOD FOR PREVENTING UNEXPECTED POWER-FAILURE USING THE SAME

• US 20100226194A1
• Filed: 01/20/2010
• Published: 09/09/2010
• Est. Priority Date: 07/20/2007
• Status: Active Grant

• Current Assignee: Memoright Memoritech (Shenzhen) Co., Ltd.
• Original Assignee: Memoright Memoritech (Shenzhen) Co., Ltd.
• Inventors: Huang, He
• Granted Patent: US 8,242,633 B2
• Time in Patent Office: Days
• US Class Current: 365/229
• CPC Class Codes: G11C 16/22 Safety or protection circuits preventing unauthorised or accidental access to memory cells

Abstract

A power failure protection circuit (10) for a non-volatile semiconductor storage device includes at least an energy storage unit (C1) that serves as a backup power supply for providing backup electrical energy when a power failure occurs. During normal operation of the device, a main control unit (12) is responsible for controlling an external power input to charge the energy storage unit, for dynamically detecting the status of the energy storage unit and for using information about the status to ensure sufficient backup electrical energy for the energy storage unit. During an abnormal operation of the power supply, the main control unit (12) is responsible for discharging the energy storage unit.

Claims

1. A method for protecting a non-volatile semiconductor storage device during a power failure of a power supply, said method comprising:

during normal operation of the device, dynamically detecting a status of the energy storage unit and controlling an external power input to charge an energy storage unit according to the status to ensure sufficient backup electrical energy for the energy storage unit; and

upon detecting an abnormality of the power supply, discharging the energy storage unit for providing power to the semiconductor storage device.

2. The method of claim 1, wherein the status of the energy storage unit is indicative of electrical energy stored in the energy storage unit and controlling an external power input to charge an energy storage unit according to the status to ensure sufficient backup electrical energy for the energy storage unit includes charging the energy storage unit when the electrical energy of the energy storage unit is insufficient and controlling the external power input to stop charging the energy storage unit after the energy storage unit is fully charged.

3. The method of claim 1, further comprising dynamically detecting whether or not the power supply is abnormal.

4. The method of claim 2, further comprising dynamically detecting whether or not the power supply is abnormal.

5. The method of claim 3, further comprising selecting the external power input to supply power during normal operation of the device, and selecting the energy storage unit to supply power during an abnormal operation.

6. The method of claim 1, further comprising adjusting a charge/discharge rate of the energy storage unit so as to ensure that the energy storage unit charges at a rate that is no less than the rate of discharge.

7. The method of claim 6, wherein adjusting a charge rate of the energy storage unit includes intermittently storing energy in an inductor and discharging said energy to the energy storage unit;

and adjusting a discharge rate of the energy storage unit includes intermittently storing energy in an inductor and discharging said energy to the storage device.

8. The method of claim 1, wherein the energy storage unit is a capacitor.

9. The method of claim 1, wherein the non-volatile semiconductor storage device is a flash memory.

10. A power failure protection circuit (10) for a non-volatile semiconductor storage device, said power failure protection circuit comprising:

an energy storage unit (C1) serving as a backup power supply for the storage device for providing backup electrical energy for the storage device when a power failure occurs; and

a main control unit (12) responsive to normal operation of the device for dynamically detecting a status of the energy storage unit and controlling an external power input to charge the energy storage unit according to said status to ensure sufficient backup electrical energy for the energy storage unit; and

being responsive to an abnormality of the power supply for discharging the energy storage unit for providing power to the semiconductor storage device.

11. The power failure protection circuit of claim 10, further comprising:

a power supply select circuit (16, J2) for selecting the external power supply to provide power to the storage device when the external power supply works normally, and selecting the energy storage unit to supply power to the storage device when the operation of the external power supply is abnormal.

12. The power failure protection circuit of claim 10, further comprising a charge/discharge control circuit (J1, L1, C1, D1, J2, D2, C2) for controlling the charge/discharge of the energy storage unit.

13. The power failure protection circuit according to claim 12, wherein the main control unit adjusts a charge/discharge rate of the energy storage unit through the charge/discharge control circuit to achieve a match between a charge/discharge voltage of the energy storage unit and a supply voltage of the storage device.

14. The power failure protection circuit of claim 1010, wherein the energy storage unit includes a capacitor (C1).

15. The power failure protection circuit of claim 14, further comprising a buck charge control circuit for feeding power from the external power input to said capacitor (C1), said buck discharge control circuit comprising a charge enable switch (J1, R12, R30, Q1), an inductor (L1) connected in series between the capacitor (C1) and the charge enable switch (J1), and a freewheeling diode (D1) connected in anti-parallel to the inductor and the capacitor (C1).

16. The power failure protection circuit of claim 14, including a buck converter for feeding power from the external power input to said capacitor (C1), said buck converter comprising a charge enable switch (J1, R12, R30, Q1), an inductor (L1) connected in series between the capacitor (C1) and the charge enable switch (J1), and a freewheeling diode (D1) connected in anti-parallel to the inductor and the capacitor (C1).

17. A power failure protection circuit (10) for a non-volatile semiconductor storage device, said power failure protection circuit comprising:

an energy storage unit (C1) serving as a backup power supply for the storage device for providing backup electrical energy for the storage device when a power failure occurs; and

a main control unit (12) responsive to normal operation of the device for controlling an external power input to charge the energy storage unit; and

being responsive to an abnormality of the power supply for discharging the energy storage unit for providing power to the storage device;

wherein said power failure protection circuit further comprises;

a buck charge control circuit for feeding power from the external power input to said capacitor (C1), said buck discharge control circuit comprising a charge enable switch (J1, R12, R30, Q1), an inductor (L1) connected in series between the capacitor (C1) and the charge enable switch (J1), and a freewheeling diode (D1) connected in anti-parallel to the inductor and the capacitor (C1); and

a boost discharge control circuit for supplying the power of the energy storage capacitor to the storage device, said boost discharge control circuit comprising a diode (D2), an inductor (L1) and an energy storage capacitor (C1), a discharge enable switch (J2) connected across the inductor and the energy storage capacitor, and a decoupling capacitor (C2) connected between an output of the power failure protection circuit and GND;

whereby the main control unit intermittently open and close the charge enable switch (J1) and the discharge enable switch (J2) to achieve a match between a charge/discharge voltage of the energy storage unit and a supply voltage of the storage device.

18. The power failure protection circuit according to claim 17, wherein the main control circuit comprises a pulse width modulator module that generates pulses corresponding to the charge enable signal and the discharge enable signal.

19. A method for protecting a non-volatile semiconductor storage device during a power failure of a power supply, said method comprising:

during normal operation of the device, controlling an external power input to charge an energy storage unit; and

upon detecting an abnormality of the power supply, discharging the energy storage unit for providing power to the semiconductor storage device;

wherein controlling an external power input to charge an energy storage unit comprises adjusting a charge rate of the energy storage unit; and

discharging the energy storage unit for providing power to the storage device comprises adjusting a discharge rate of the energy storage unit ensure that the energy storage unit charges at a rate that is no less than the rate of discharge.

20. The method according to claim 19, wherein adjusting the charge rate of the energy storage unit includes intermittently storing energy in an inductor and discharging said energy to the energy storage unit;

and adjusting the discharge rate of the energy storage unit includes intermittently storing energy in an inductor and discharging said energy to the storage device.