JP2001022653A - Non-volatile semiconductor storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To guarantee the contents of data in an EEPROM under writing even when the operation of a non-volatile semiconductor storage device (non- contact IC card) is interrupted during the execution of write. SOLUTION: A backup area 1-B is provided in a data area 1-A of an EEPROM part 4, un-written data, address information and parity information in the data area 1-A of the EEPROM part 4 are written into the backup area 1-B, and a backup operation control circuit 15 is provided for repairing data in the data area 1-A by referring to data in the data area 1-A and the backup area 1-B when the execution of reloading of data into the data area 1-A is interrupted. Thus, even when the execution of reloading of data is interrupted, data in the data area 1-A can be repaired.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonvolatile semiconductor memory device used as a non-contact IC card or the like.

[0002]

2. Description of the Related Art In recent years, along with a demand for a security function of an IC card, a demand for reliability of EEPROM data in the IC card has been increasing. In response to this demand for high data reliability, conventionally, device-specific characteristics such as the guaranteed number of rewrites and data retention time as memory cells of an EEPROM have been improved. However, in the EEPROM for a non-contact IC card, the radio wave from the antenna is a source of the power supply voltage, and therefore, the EEPROM depends on the state of the radio wave depending on the distance between the antenna and the IC card.
The power supply voltage sometimes dropped during data rewriting of M (memory cell). If the power supply voltage falls below the write operation range in this way, rewriting may be completed in an insufficiently rewritten state, and therefore a write error signal is output from the write inhibit circuit. It was impossible to guarantee the contents of the data. For this reason, it is required to establish measures for ensuring the reliability of the rewrite data of the EEPROM for the non-contact IC card.

Hereinafter, an example of a circuit of a conventional non-contact IC card (an example of a nonvolatile semiconductor memory device) will be described with reference to FIG. The conventional non-contact IC card C is
LSI 10 with EEPROM for C card and antenna unit 1
1 is formed. The LSI 10 includes an EEPR including a data area 1, a write circuit 2 for performing a write operation on the data area 1, and a read circuit 3 for performing a read operation on the data area 1.
When the OM unit 4 and a power supply voltage (described later) fall below the write operation range, a write error signal a is output,
A write inhibit circuit 6 for inhibiting the execution of the write operation in the EEPROM unit 4; a power reset circuit 7 for inhibiting the execution of the write / read operation in the EEPROM unit 4 when the power supply voltage falls below the write / read operation range. , A power supply regulation circuit 8 and a power supply generation circuit (an example of a power supply unit) 9. Power is generated in the power generation circuit 9 based on the radio wave received by the antenna unit 11, and the excessive rise of the power supply voltage is prevented by conducting between the power supply and the ground potential in the power supply regulation circuit 8. Have been.

[0004] The operation of the non-contact IC card configured as described above will be described below. First, a power supply is generated by a power supply generation circuit 9 based on a radio wave received by the antenna unit 11, and this power supply is connected to an EEPROM mounted on a non-contact IC card.
Supply to the entire SI10. This power supply voltage is a non-contact IC
The power supply voltage depends on the distance between the card C and the (external) antenna that performs transmission and reception with the non-contact IC card C. The power supply voltage increases as the distance decreases and the power supply voltage decreases as the distance increases.

When the distance is short, the power supply regulation circuit 8
Thus, for device protection, a regulation operation is performed so that the power supply voltage does not rise above a certain fixed voltage. Therefore, a power supply voltage sufficient for executing the write / read operation is stably supplied, so that the write / read operation for the data area 1 can be executed using the write circuit 2 and the read circuit 3. However, when the distance is long, if the power supply voltage falls below the write / read operation range, the execution of the write operation is prohibited by the write inhibit circuit 6, and the execution of the write / read operation is prohibited by the power reset circuit 7. However, even when the rewriting is insufficient, the rewriting has been completed. Then, a write error signal a is output from the write inhibit circuit 6.

[0006]

However, in the above-described conventional configuration, when the power supply voltage falls below the write operation range during the execution of the write operation of the EEPROM section 4 for the non-contact IC card, a write error signal is output from the write inhibit circuit 6. Although a is output, there is a problem that it is impossible to guarantee the contents of the data being written.

The present invention relates to a nonvolatile semiconductor memory device used as such a non-contact IC card and the like.
It is an object of the present invention to be able to guarantee the contents of EEPROM data being written even when the power supply voltage falls below the write operation range during writing.

[0008]

According to the present invention, there is provided a nonvolatile semiconductor memory device comprising an EEPROM comprising a data area, a write circuit for performing a write operation on the data area, and a read circuit for performing a read operation on the data area. A backup area provided in a data area of the EEPROM section, and data, address information, and parity information before writing in the data area of the EEPROM section are transferred to the backup area. A backup operation control circuit for restoring data in the data area by referring to the data in the data area and the backup area when execution is interrupted during writing and rewriting of data in the data area is provided. It was .

According to the present invention, even when the power supply voltage drops below the write operation range during the execution of the write operation and the write operation is interrupted, the nonvolatile content of the EEPROM data being written can be assured. A semiconductor memory device is obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides an EEPROM unit comprising a data area, a write circuit for performing a write operation on the data area, and a read circuit for performing a read operation on the data area. Wherein a backup area is provided in a data area of the EEPROM section, and data, address information, and parity information before writing in the data area of the EEPROM section are written in the backup area. , When its execution is interrupted while rewriting data in the data area,
A backup operation control circuit for restoring data in the data area by referring to data in the data area and the backup area is provided. The data and address information before writing in the data area in the EEPROM section are provided. And the parity information are written to the backup area, so that the power supply drops below the rewriting operating voltage during the data rewrite, and when the execution of the data rewrite is interrupted, the data area and the backup area are not rewritten. By referring to the data, the data area can be repaired.

According to a second aspect of the present invention, there is provided a data area,
A nonvolatile semiconductor memory device comprising: a write circuit for performing a write operation on the data area; and an EEPROM unit including a read circuit for performing a read operation on the data area.
A plurality of backup areas are provided in the data area of the M section, and the EEPROM section is provided with a backup area / address counter for counting the number of times of writing for each address in the backup area and sequentially changing the address in the backup area for each writing. Provided, the EEP
The data, address information, and parity information before writing in the data area of the ROM section are written to the backup area designated by the backup area / address counter, and the execution is interrupted while the data area is being rewritten. A backup operation control circuit for restoring data in the data area by referring to data in the backup area designated by the data area and the backup area / address counter, EEP
By writing the data, address information, and parity information before writing in the data area of the ROM section while sequentially designating a plurality of backup areas by the backup area / address counter, that is, writing while changing the address sequentially, the data of the data is written. When the power supply drops below the rewriting operating voltage during rewriting and the execution of data rewriting is interrupted, the data in the data area and the data in the backup area specified by the backup area / address counter are referenced to allow the data to be rewritten. This has the effect of enabling restoration and further improving the number of times of rewriting of the backup area.

The invention according to claim 3 is the invention according to claim 2, wherein the antenna unit, a power supply unit for generating power based on radio waves received by the antenna unit, and the power supply unit A power supply voltage detection circuit that releases the backup function of the backup operation control circuit when the power supply voltage to be supplied is equal to or higher than a predetermined value. Is greater than or equal to a certain value, the backup function is released and unnecessary backup operation is not performed when the power supply is sufficient, so that the number of times of rewriting the backup area can be further improved.

The invention according to claim 4 is the invention according to claim 2, wherein the antenna section, a power supply section for generating power based on radio waves received by the antenna section, and a power supply-ground potential A power supply voltage regulating circuit for preventing an excessive rise of the power supply voltage by conducting the power supply voltage, and the backup operation control circuit when a regulated current flowing between a power supply and a ground potential by the power supply voltage regulating circuit is a predetermined value or more. The power supply voltage regulation circuit releases the backup function when the regulated current flowing between the power supply and the ground potential exceeds a certain value. By not performing unnecessary backup operations when the power supply is sufficient, the number of times of rewriting the backup area can be further increased. It has the effect that it is possible to above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same components as those of the conventional example shown in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted. [First Embodiment] FIG. 1 is a circuit diagram of a non-contact IC card which is a nonvolatile semiconductor memory device according to a first embodiment of the present invention.

In the first embodiment of the present invention, the EEP
In the ROM section 4, a backup area 1-B is provided in the data area 1-A, and a backup operation control circuit (to be described in detail later) 15 is newly provided. The operation of the non-contact IC card configured as described above will be described below.

First, a power supply is generated by a power supply generation circuit 9 based on a radio wave received by the antenna section 11, and this power supply is
It is supplied to the entire LSI 10 equipped with the EEPROM for the C card. The power supply voltage depends on the distance between the (external) antenna and the non-contact IC card C. The power supply voltage increases as the distance is shorter, and the power supply voltage decreases as the distance is longer. If the distance is short, a regulation operation is performed by the power supply regulation circuit 8 so that the power supply voltage does not rise to a certain fixed voltage or more for device protection.

Here, the procedure of rewriting data will be described with reference to the explanatory diagram of FIG. First, the writing circuit 2
This puts the data in the backup area 1-B before the writing operation into the erased state. Next, data in the data area 1-A before writing is executed is read by the read circuit 3, and the read data, address information, and parity information are written by the write circuit 2 to the backup area 1-A.
Write in B.

Next, the write circuit 2 erases the data in the data area 1-A at the address to be written. Next, the data area 1-1 is written by the write circuit 2.
Write new data to A. Finally, the writing circuit 2
To erase the data in the backup area 1-B, the address information, and the data of the parity information to bring them into an erased state,
Return to the first erased state.

Data area 1 according to the rewriting procedure
The operation of the backup operation control circuit 15, ie, the restoration of data by the backup operation control circuit 15, when the power supply voltage falls below the write operation range during the data rewriting of A and the write operation is interrupted by the write inhibit circuit 6. The method will be described with reference to the flowchart of FIG. The restoration of this data is executed after the power is turned on again.

First, the data in the backup area 1-B is read (step-1), and it is determined whether or not the read data is erase data (step-2).
When the read data is erase data, the data area 1-
It is determined that data before rewriting or data after rewriting is written in A (step-3). In step 2 above, when some data or address information and parity information are written in the read data of the backup area 1-B, the data of the corresponding address in the data area 1-A is read based on the address information (step 2). -4).

Next, it is determined whether or not the read data of the data area 1-A is erase data (step-5). If the read data is erased data, it is determined that the data before rewriting has been written in the backup area 1-B (step-6). Next, it is determined whether the read data in the backup area 1-B and the data in the data area 1-A are the same (step-7). If the same data has been written, the data area 1-A before the rewriting is written into the data area 1-A. Judge that data has been written (step-
8).

If the read data are not the same in step-7, it is determined whether the parity information in the backup area 1-B is proper data (step-9).
If the parity information of the backup area 1-B is proper data, it is determined that the data after rewriting is written in the data area 1-A and the data before rewriting is written in the backup area 1-B. (Step-1
0). However, if the parity information of the backup area 1-B is not proper data, the data before rewriting is written in the data area 1-A, and the writing of the data before rewriting is interrupted in the backup area 1-B. It is determined that correct data has not been written (step-11).

The data in the data area 1-A is restored with reference to the data in the data area 1-A and the backup area 1-B determined above (step-12). Therefore, even if the power supply voltage falls below the write operation range and the write operation is interrupted by the write inhibit circuit 6, the data in the data area 1-A and the data in the backup area 1-B can be referred to. -A data can be restored.

As described above, according to the first embodiment, E
A backup area 1-B is provided in the data area 1-A in the EPROM section 4, and the write circuit 2, the read circuit 3,
It includes a power reset circuit 7, a write inhibit circuit 6, and a backup operation control circuit 15, and writes data, address information, and parity information of the data area 1-A of the EEPROM section 4 before writing to the backup area 1-B. Thus, even if the power supply drops below the operating voltage for rewriting during data rewriting and the data rewriting operation is interrupted and cannot be completed normally, the data area 1-A and the backup area 1-B are not , The data in the data area 1-A can be restored. Second Embodiment FIG. 4 is a circuit diagram of a non-contact IC card which is a nonvolatile semiconductor memory device according to a second embodiment of the present invention.

In the second embodiment, in addition to the configuration of the first embodiment, a backup area
An address counter 12 is provided. The backup area / address counter 12 counts the number of times of writing for each address in the backup area 1-B, and sequentially changes the address in the backup area 1-B for each writing. Also, there are a plurality of backup areas 1-B.

The operation of the non-contact IC card configured as described above will be described below. First, a power source is generated by a power source generating circuit 9 based on a radio wave received by the antenna unit 11, and the power source is connected to an EEPROM for a non-contact IC card.
It is supplied to the entire mounted LSI 10. The power supply voltage depends on the distance between the (external) antenna and the non-contact IC card C. The power supply voltage increases as the distance is shorter, and the power supply voltage decreases as the distance is longer.

If the distance is short, the power supply regulation circuit 9
Thus, for device protection, a regulation operation is performed so that the power supply voltage does not rise above a certain fixed voltage. Here, the procedure of rewriting data will be described with reference to the explanatory diagram of FIG. First, the write circuit 2 puts the data in the backup area 1-B indicated by the backup area / address counter 12 before the write operation into an erased state.

Next, the data in the data area 1-A before the writing is executed is read by the reading circuit 3,
The read data, address information and parity information are written by the write circuit 2 into the backup area 1-B indicated by the backup area / address counter 12. Next, the write circuit 2 erases the data in the data area 1-A at the address where the write is desired.

Next, new data is written to the data area 1-A by the write circuit 2. Finally, the write area 2 controls the backup area / address counter 12
And erases the data in the backup area 1-B, the address information, and the parity information indicated by the
Return to the first erased state. At this time, the backup area / address counter 12 is incremented, and the information is written into the EEPROM unit 4.

As described above, the backup area / address counter 12 writes the data, the address information, and the parity information of the data area 1-A before writing to the plurality of backup areas 1-B while sequentially changing the addresses. It is. A method of restoring data in the backup operation control circuit 15 when the power supply voltage falls below the write operation range and the write operation is interrupted by the write inhibit circuit 6 during the data rewrite of the data area 1-A by the rewrite procedure. Is the same as the procedure shown in the flowchart of FIG. 3 of the first embodiment, and the description is omitted.

The data in the backup area 1-B is read from the backup area 1-B designated by the backup area / address counter 12, and is determined based on the read data. As described above, according to the second embodiment, the data area 1-
A and a plurality of backup areas 1-B. The backup area / address counter 12 counts the number of times of writing for each address in the backup area 1-B, and sequentially changes the address in the backup area 1-B for each writing. A write circuit 2, a read circuit 3, a power reset circuit 7, and a write inhibit circuit 6, and the data, address information, and parity information of the data area 1-A of the EEPROM unit 4 before writing. To the backup area / address counter 12
Is written in the backup area 1-B, the power supply drops below the rewriting operation voltage during data rewriting, and even if the data rewriting operation is interrupted and cannot be completed normally, Area 1
By referring to the data in the backup area 1-A and the data in the backup area 1-B, the data in the data area 1-A can be restored and the backup area 1-B can be restored.
Can be improved. [Third Embodiment] FIG. 6 is a circuit diagram of a non-contact IC card which is a nonvolatile semiconductor memory device according to a third embodiment of the present invention.

In the third embodiment, a power supply voltage detecting circuit 13 for canceling the backup function when the power supply voltage generated by the power supply section is equal to or higher than a certain value is newly provided in the configuration of the second embodiment. Non-contact I configured as described above
The operation of the C card will be described below.

First, a power supply is generated by a power supply generation circuit 9 based on a radio wave received by the antenna unit 11, and this power supply is
It is supplied to the entire LSI 10 equipped with the EEPROM for the C card. The power supply voltage depends on the distance between the (external) antenna and the non-contact IC card C. The power supply voltage increases as the distance is shorter, and the power supply voltage decreases as the distance is longer. If the distance is short, a regulation operation is performed by the power supply regulation circuit 8 so that the power supply voltage does not rise to a certain fixed voltage or more for device protection. Next, when the power supply voltage generated by the power supply regulation circuit 8 is equal to or higher than a predetermined value, the power supply voltage detection circuit 13 cancels the backup function using the backup area 1-B as in the second embodiment. . That is, when the power supply voltage is sufficiently supplied, it is understood that the distance between the antenna and the non-contact IC card C is short. Therefore, the power supply instantaneously drops and the write operation is not interrupted, so that the backup function becomes unnecessary.

When the power supply voltage generated by the power supply regulation circuit 8 is equal to or lower than a predetermined value by the power supply voltage detection circuit 13, the backup function is performed similarly to the second embodiment. Therefore, when the power supply voltage generated by the power supply regulation circuit 8 by the power supply voltage detection circuit 13 is equal to or higher than a predetermined value, the backup function is released and unnecessary backup operation when the power supply is sufficient is not performed. In addition to the operation described in the second embodiment, the number of times of rewriting of the backup area 1-B can be further improved.

As described above, according to the third embodiment, the non-contact IC card EEPROM unit 4 of the second embodiment
A power supply unit for generating power based on radio waves received by the antenna unit; and a power supply voltage detection circuit for canceling the backup function when the power supply voltage generated by the power supply unit is equal to or higher than a predetermined value. When the power supply voltage generated by the power supply unit by the detection circuit 13 is equal to or higher than a certain value, the backup function is released and unnecessary backup operation when power supply is sufficient is not performed, so that the operation according to the second embodiment is performed. In addition, the number of times of rewriting of the backup area 1-B can be further improved. [Fourth Embodiment] FIG. 7 is a circuit diagram of a non-contact IC card which is a nonvolatile semiconductor memory device according to a fourth embodiment of the present invention.

In the fourth embodiment, the backup function is released when the regulated current flowing between the power supply and the ground potential is a predetermined value or more by the power supply voltage regulating circuit 8 in addition to the configuration of the second embodiment. A regulation current detection circuit 14 is provided. The operation of the non-contact IC card configured as described above will be described below.

First, a power source is generated by a power source generating circuit 9 based on a radio wave received by the antenna unit 11, and this power source is
It is supplied to the entire LSI 10 equipped with the EEPROM for the C card. The power supply voltage depends on the distance between the (external) antenna and the non-contact IC card C. The power supply voltage increases as the distance is shorter, and the power supply voltage decreases as the distance is longer. If the distance is short, a regulation operation is performed by the power supply regulation circuit 8 so that the power supply voltage does not rise to a certain fixed voltage or more for device protection. During the regulation operation, an excessive power supply voltage rise is prevented by conducting between the power supply and the ground potential.

Next, when the regulated current flowing between the power supply and the ground potential is equal to or more than a predetermined value, the regulated current detecting circuit 14 releases the backup function using the backup area as in the second embodiment. I do. That is, when the regulation current is equal to or more than a certain value, the supply of the power supply voltage is sufficient, and it is understood that the distance between the antenna and the non-contact IC card C is short. Therefore, the power supply instantaneously drops and the write operation is not interrupted, so that the backup function becomes unnecessary. Further, when the regulated current flowing between the power supply and the ground potential is equal to or less than a predetermined value by the regulated current detection circuit 14, a backup function similar to that of the second embodiment is performed. Therefore,
The regulation current detection circuit 14 releases the backup function when the regulation current is equal to or more than a certain value, and does not perform an unnecessary backup operation when the power supply is sufficient. in addition,
The number of times of rewriting of the backup area 1-B can be further improved.

As described above, according to the fourth embodiment, the non-contact IC card EEPROM unit 4 of the second embodiment
A power supply unit that generates power based on radio waves received by the antenna unit 11 and a regulated current detection circuit 14 that releases the backup function when the regulated current flowing between the power supply and the ground potential is equal to or more than a certain value. When the regulated current flowing between the power supply and the ground potential is equal to or more than a predetermined value by the regulated current detection circuit 14, the backup function is released and unnecessary backup operation when the power supply is sufficient is not performed. In addition to the operation described in the second embodiment, the number of times of rewriting of backup area 1-B can be further improved.

In this embodiment, a non-contact IC card is described as a non-volatile semiconductor memory device. However, the present invention is not limited to a non-contact IC card, and the power supply voltage may be changed during a write operation. The present invention can be applied to a storage device in which the write operation is interrupted when the write operation falls below the range.

[0041]

As described above, according to the present invention, during rewriting of data, the power supply drops below the rewriting operating voltage,
Even if the data rewriting operation is interrupted, after the power is turned on again, by referring to the data in the data area of the EEPROM unit and the data in the backup area, an advantageous effect that the data can be restored can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a non-contact IC card which is a nonvolatile semiconductor memory device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a data write operation in the non-contact IC card.

FIG. 3 is a flowchart illustrating a method of restoring data in the non-contact IC card.

FIG. 4 is a circuit diagram of a non-contact IC card which is a nonvolatile semiconductor memory device according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a data writing operation in the contactless IC card.

FIG. 6 is a circuit diagram of a non-contact IC card which is a nonvolatile semiconductor memory device according to a third embodiment of the present invention.

FIG. 7 is a circuit diagram of a non-contact IC card which is a nonvolatile semiconductor memory device according to a fourth embodiment of the present invention.

FIG. 8 shows a non-contact I which is a conventional nonvolatile semiconductor memory device.
It is a circuit diagram of a C card.

[Explanation of symbols]

 C IC card 1-A Data area 1-B Backup area 2 Write circuit 3 Read circuit 4 EEPROM section 6 Write inhibit circuit 7 Power reset circuit 8 Power regulation circuit 9 Power generation circuit 10 Non-contact IC card EEPROM mounted LSI 11 Antenna Unit 12 Backup area / address counter 13 Power supply voltage detection circuit 14 Regulated current detection circuit 15 Backup operation control circuit a Write error signal

Claims (4)

[Claims] 1. A non-volatile semiconductor storage device comprising: a data area; a write circuit for performing a write operation on the data area; and an EEPROM unit including a read circuit for performing a read operation on the data area, A backup area is provided in the data area of the EEPROM section, and data, address information, and parity information before writing in the data area of the EEPROM section are written in the backup area, and the execution is interrupted during rewriting of data in the data area. The data area and the data in the backup area,
A nonvolatile semiconductor memory device comprising a backup operation control circuit for restoring data in a data area. 2. A nonvolatile semiconductor memory device comprising: a data area; a write circuit for performing a write operation on the data area; and an EEPROM unit including a read circuit for performing a read operation on the data area, A plurality of backup areas are provided in the data area of the unit, and the EEPROM unit is provided with a backup area address counter for counting the number of times of writing for each address in the backup area and sequentially changing the address in the backup area for each writing. The data, address information, and parity information before writing in the data area of the EEPROM section are written to the backup area designated by the backup area / address counter, and the data is written to the data area. A backup operation control circuit for restoring data in the data area by referring to the data in the data area and the backup area designated by the backup area / address counter when the execution is interrupted during rewriting; A nonvolatile semiconductor memory device characterized by the above-mentioned. 3. An antenna unit, a power supply unit for generating power based on radio waves received by the antenna unit, and a backup of the backup operation control circuit when a power supply voltage generated by the power supply unit is a predetermined value or more. 3. The nonvolatile semiconductor memory device according to claim 2, further comprising a power supply voltage detection circuit for canceling the function. 4. An antenna unit, a power supply unit that generates power based on radio waves received by the antenna unit, and a power supply voltage regulation circuit that prevents excessive power supply voltage rise by conducting between a power supply and a ground potential. And a regulating current detecting circuit for canceling a backup function of the backup operation control circuit when a regulating current flowing between a power supply and a ground potential by the power supply voltage regulating circuit is equal to or more than a certain value. The nonvolatile semiconductor memory device according to claim 2.