Thin film magnetic memory device suitable for drive by battery

1. A thin film magnetic memory device comprising:

a plurality of first write current lines for selectively feeding a first data write current;

a plurality of magnetic memory cells into which data is written by application of magnetic field produced by said first data write current;

a first switching element provided corresponding to one end of each of said first write current lines; wherein

said first switching element is arranged to allow said first data write current to flow by connecting corresponding one of said first current write lines charged to a first voltage to a second voltage different from said first voltage;

a second switching element provided corresponding to the other end of each of said first write current lines, wherein

said second switching element is conducted during at least a part of a non-conducted period of said first switching element, so as to electrically connect said corresponding first write current line to said first voltage, and is rendered non-conducting during a conducted period of said first switching element, so as to electrically disconnect said corresponding first write current line from said first voltage.

2. The thin film magnetic memory device according to claim 1 , further comprising a charge adjusting resistor arranged so as to be electrically connected between corresponding one of said first write current lines and said first voltage during a period in which said second switching element is conducted.

3. A thin film magnetic memory device comprising:

a plurality of first write current lines for selectively feeding a first data write current;

a plurality of magnetic memory cells into which data is written by application of magnetic field produced by said first data write current;

a first switching element provided corresponding to one end of each of said first write current lines; wherein

said first switching element is arranged to allow said first data write current to flow by connecting corresponding one of said first current write lines charged to a first voltage to a second voltage different from said first voltage;

a sub switching element provided corresponding to said one end of each of said first write current lines, wherein

said first switching element is arranged to allow said first data write current to flow in response to conduction of the first switching element itself, and is rendered non-conducting when corresponding one of said first write current lines is charged to said second voltage and said first data write current no longer flows, and

said sub switching element is connected after said first switching element is rendered non-conducting, and electrically connects said corresponding first write current line charged to said second voltage to said first voltage, so as to allow said first data write current to flow.

4. A thin film magnetic memory device comprising:

a plurality of first write current lines for selectively feeding a first data write current;

a plurality of magnetic memory cells into which data is written by application of magnetic field produced by said first data write current;

a first switching element provided corresponding to one end of each of said first write current lines; wherein

said first switching element is arranged to allow said first data write current to flow by connecting corresponding one of said first current write lines charged to a first voltage to a second voltage different from said first voltage; and

an additional capacitor connected to each of said first write current lines upstream from said plurality of magnetic memory cells on a path for charging each of said first write current lines to said first voltage.

5. The thin film magnetic memory device according to claim 4 , wherein

said additional capacitor is provided corresponding to each of said plurality of first write current lines.

6. The thin film magnetic memory device according to claim 4 , wherein

said additional capacitor is commonly connected to at least two of said plurality of first write current lines.

7. The thin film magnetic memory device according to claim 4 , wherein

said additional capacitor is configured to include a capacitive component of a hierarchically higher write line provided hierarchically with respect to said plurality of first write current lines.

8. A thin film magnetic memory device comprising:

a plurality of first write current lines for selectively feeding a first data write current;

a plurality of magnetic memory cells into which data is written by application of magnetic field produced by said first data write current;

a first switching element provided corresponding to one end of each of said first write current lines; wherein

said first switching element is arranged to allow said first data write current to flow by connecting corresponding one of said first current write lines charged to a first voltage to a second voltage different from said first voltage;

a plurality of second write current lines for selectively feeding a second data write current in a direction in accordance with write data,

a write node set to one of a plurality of data voltages in accordance with the write data,

a third switching element provided corresponding to one end of each of said second write current lines and for electrically connecting said one end to said write node, and

a plurality of fourth switching elements for electrically connecting the other ends of said second write current lines to said plurality of data voltages respectively, wherein

said first data write current flows in a prescribed direction on selected one of said first write current lines, regardless of said write data,

said write data is written in each of said magnetic memory cells depending on a combination of magnetic fields produced by said first data write current and said second data write current respectively,

said third switching element is rendered non-conducting after corresponding one of said second write current lines is charged to a voltage of said write node in response to conduction of the third switching element itself, and

said second data write current is allowed to flow when one of said plurality of fourth switching elements, corresponding to a data voltage different from the voltage of said write node, is conducted after said third switching element is rendered non-conducting.

9. The thin film magnetic memory device according to claim 8 , wherein

a plurality of fourth switching elements are connected one by one in a prescribed order during a single data write operation, regardless of a level of said write data.

10. The thin film magnetic memory device according to claim 8 , wherein

one of said plurality of fourth switching elements in accordance with a level of said write data is selectively conducted during a single data write operation.

11. The thin film magnetic memory device according to claim 8 , further comprising a charge adjusting resistor arranged so as to be electrically connected between corresponding one of said second write current lines and said write node during a period in which said third switching element is conducted.

12. The thin film magnetic memory device according to claim 8 , further comprising an additional capacitor connected to each of said second write current lines upstream from said plurality of magnetic memory cells on a path for charging each of said second write current lines to the voltage of said write node.

13. The thin film magnetic memory device according to claim 12 , wherein

said additional capacitor is provided corresponding to each of said plurality of second write current lines.

14. The thin film magnetic memory device according to claim 12 , wherein

said additional capacitor is configured to include a capacitive component of a hierarchically higher write line electrically connected between said write node and said plurality of second write current lines.

15. A thin film magnetic memory device comprising:

a plurality of first write current lines for selectively feeding a first data write current;

a plurality of magnetic memory cells into which data is written by application of magnetic field produced by said first data write current;

a first switching element provided corresponding to one end of each of said first write current lines; wherein

said first switching element is arranged to allow said first data write current to flow by connecting corresponding one of said first current write lines charged to a first voltage to a second voltage different from said first voltage;

a plurality of second write current lines for selectively feeding a second data write current in a direction in accordance with write data,

first and second write nodes charged to one and another one of a plurality of data voltages in accordance with a level of the write data, respectively,

a third switching element provided corresponding to one end of each of said second write current lines and for electrically connecting said one end to said first write node, and

a fourth switching element provided corresponding to the other end of each of said second write current lines and for electrically connecting said other end to said second write node, wherein

said first data write current flows in a prescribed direction on selected one of said first write current lines, regardless of said write data,

said write data is written in each of said magnetic memory cells depending on a combination of magnetic fields produced by said first data write current and said second data write current respectively, and

said third and fourth switching elements are rendered non-conducting during charging of said first and second write nodes, and conducted in order to allow said second data write current to flow after said first and second write nodes are charged.

16. The thin film magnetic memory device according to claim 15 , further comprising charge adjusting resistors connected in series to paths for charging said first and second write nodes respectively.

17. A thin film magnetic memory device, comprising:

a plurality of write current lines for feeding a data write current flowing in a direction in accordance with write data;

a plurality of magnetic memory cells into which data is written by application of data write magnetic field produced by said data write current;

a data bus set to one of a plurality of data voltages in accordance with a level of said write data;

a first write switching element provided corresponding to one end of each of said write current lines and for electrically connecting said one end to said data bus; and

a plurality of second write switching elements for electrically connecting the other ends of said write current lines to said plurality of data voltages respectively; wherein

one of said plurality of second write switching elements, corresponding to a data voltage different from a voltage of said data bus, is conducted in order to allow said second data write current to flow.

18. A thin film magnetic memory device, comprising:

a plurality of write current lines for feeding a data write current flowing in a direction in accordance with write data;

a plurality of magnetic memory cells into which data is written by application of data write magnetic field produced by said data write current;

a first write driver shared by at least two write current lines of said plurality of write current lines; and

a second write driver arranged corresponding to each of said plurality of write current lines; wherein

said first write driver connects one end side of said at least two write current lines to one of a plurality of data voltages in accordance with a level of the write data when said at least two write current lines sharing the first write driver include a data write target, and

said second write driver connects the other end side of corresponding write current line to another one of said plurality of data voltages when the corresponding write current line is the data write target, while it disconnects the other end side of the corresponding write current line from any other one of said plurality of data voltages when the corresponding write current line is not the data write target.