Semiconductor device having PDA function
A method for writing a mode register in a semiconductor device, the method includes receiving a mode register command and a mode signal; generating a first mode register setting signal; delaying the first mode register setting signal in a first latency shifter to provide a second mode register setting signal; receiving a data signal in synchronization with the second mode register setting signal; and writing the mode signal to the mode register only if the received data signal has a first logic level.
1. A method for controlling a plurality of memory devices comprising:
supplying a first command in common to the plurality of memory devices to enable a PDA function; and
supplying a second command in common to the plurality of memory devices to overwrite a first mode register in a first memory device of the plurality of memory devices;
wherein a contents of the first mode register in the first memory device of the plurality of memory devices are overwritten with information supplied with the second command when a first data signal provided to the first memory device has a first logic level, and the contents of a first mode register in a second memory device of the plurality of memory devices are not overwritten with the information supplied with the second command when a second data signal provided to the second memory device has a second logic level opposite the first logic level.
2. The method as claimed in claim 1 , wherein the first logic level is a low logic level and the second logic level is a high logic level.
3. The method as claimed in claim 1 , wherein the first command enables the PDA function in each of the plurality of memory devices.
4. The method as claimed in claim 3 , wherein the first command overwrites a second mode register in each of the plurality of memory devices to enable the PDA function in each of the plurality of memory devices.
5. The method as claimed in claim 4 , wherein the second mode register in each of the plurality of memory devices is MR 0 .
6. The method as claimed in claim 1 , wherein the first mode register in each of the plurality of memory devices is MR 1 .
7. The method as claimed in claim 1 , wherein the first data signal and the second data signal are provided after the second command.
8. The method as claimed in claim 7 , wherein the first data signal and the second data signal are provided after a lapse of a write latency following the second command.
9. The method as claimed in claim 1 , wherein the plurality of memory devices are DRAM devices.
10. The method as claimed in claim 1 , further comprising:
supplying a third command in common to the plurality of memory devices to overwrite a second mode register in a third memory device of the plurality of memory devices;
wherein the contents of a first mode register in the third memory device of the plurality of memory devices are not overwritten with the information supplied with the second command when a third data signal provided to the third memory device has the second logic level;
wherein the contents of a second mode register in the first memory device of the plurality of memory devices are not overwritten with information supplied with the third command when a fourth data signal provided to the first memory device has the second logic level, wherein the contents of a second mode register in the second memory device of the plurality of memory devices are not overwritten with the information supplied with the third command when a fifth data signal provided to the second memory device has the second logic level, and the contents of the second mode register in the third memory device of the plurality of memory devices are overwritten with the information supplied with the third command when a sixth data signal provided to the third memory device has the first logic level.
11. The method as claimed in claim 10 , wherein the first mode register and the second mode register are the same mode register.
12. The method as claimed in claim 10 , wherein the first data signal, the second data signal, and the third data signal are provided after the second command, and the fourth data signal, the fifth data signal, and the sixth data signal are provided after the third command.
13. The method as claimed in claim 12 , wherein the first data signal, the second data signal, and the third data signal are provided after a lapse of a write latency following the second command, and the fourth data signal, the fifth data signal, and the sixth data signal are provided after a lapse of a write latency following the third command.
14. The method as claimed in claim 10 , wherein the plurality of memory devices are DRAM devices.