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 controller comprising:
an output circuit that supplies a mode register command and a mode signal in common to a plurality of memory devices; and
a data processing circuit that:
supplies a first enable signal having a first logic level to a first memory device of the plurality of memory devices, the first enable signal being supplied with a predetermined latency after supplying the mode register command and the mode signal; and
supplies a second enable signal having a second logic level to a second memory device of the plurality of memory devices, the second signal being supplied with the predetermined latency after supplying the mode register command and the mode signal;
wherein the mode register command is decoded and delayed by a latency shifter in each of the plurality of memory devices, the mode signal is written to a first mode register of the first memory device in response to the first enable signal having the first logic level, and the mode signal is not written to a first mode register of the second memory device in response to the second enable signal having the second logic level.
2. The controller of claim 1 , wherein the predetermined latency comprises a write latency.
3. The controller of claim 1 , wherein the predetermined latency comprises an additive latency.
4. The controller of claim 1 , wherein the predetermined latency comprises a write latency and an additive latency.
5. The controller of claim 1 , wherein the mode signal is supplied to address terminals of the plurality of memory devices.
6. The controller of claim 1 , wherein the first and second enable signals are supplied to data terminals of respective memory devices.
7. The controller of claim 1 , wherein the first logic level is a low logic level and the second logic level is a high logic level.
8. The controller of claim 1 , wherein the output circuit supplies a plurality of selection signals in common to the plurality of memory devices, wherein the first and second memory devices comprise a plurality of respective mode registers in addition to respective first mode registers and the plurality of selection signals selects the first mode registers.
9. The controller of claim 8 , wherein the plurality of selection signals are supplied to bank address terminals of the plurality of memory devices.
10. The controller of claim 8 , wherein the plurality of selection signals are encoded selection signals.
11. The controller of claim 1 , wherein the output circuit supplies a first chip select signal having an active state in common to the first and second memory devices, supplies a second chip select signal having an inactive state in common to third and fourth memory devices of the plurality of memory devices, supplies the first enable signal to the third memory device, and supplies the second enable signal to the fourth memory device, wherein the mode signal is not written to a first mode register of the third memory device and a second mode register of the fourth memory device.
12. The controller of claim 11 , wherein the active state is a high logic level and the inactive state is a low logic level.
13. The controller of claim 1 , wherein the data processing circuit processes read data, write data, or a combination thereof through a data terminal.
14. The controller of claim 1 , wherein the output circuit supplies an address signal, a chip select signal, a clock signal, or some combination thereof.
15. An information processing system comprising:
a plurality of memory devices; and
a controller comprising:
an output circuit that supplies a mode register setting command and a mode signal to the plurality of memory devices in common; and
a data processing circuit that:
supplies data signals to each of the memory devices, receives data signals from each of the memory devices, or a combination thereof; and
supplies a first enable signal having a first logic level to a first memory device of the plurality of memory devices, the first enable signal being supplied with a predetermined latency after supplying the mode register command and the mode signal;
wherein each memory device of the plurality of memory devices comprises:
a command decoder that activates a first mode register setting signal in response to the mode register setting command supplied from the output circuit;
a latency shifter that delays the first mode register setting signal; and
a mode register that stores the mode signal supplied from the output circuit in response to the first enable signal having the first logic level and does not store the mode signal supplied from the output circuit in response to the first enable signal having a second logic level.
16. The information processing system of claim 15 , wherein the mode signal is supplied to address terminals of the plurality of memory devices.
17. The information processing system of claim 15 , wherein the data signals are supplied to data terminals of the plurality of memory devices.
18. The information processing system of claim 15 , wherein the first logic level is a low logic level.
19. The information processing system of claim 15 , wherein the output circuit supplies a plurality of selection signals in common to the plurality of memory devices, wherein the plurality of memory devices comprises a plurality of respective mode registers in addition to respective mode registers and the plurality of selection signals selects the mode registers.
20. The information processing system of claim 19 , wherein the plurality of selection signals are supplied to bank address terminals of the plurality of memory devices.
21. The information processing system of claim 19 , wherein the plurality of selection signals are encoded selection signals.
22. The information processing system of claim 15 , wherein the output circuit supplies a first chip select signal having an active state in common to first and second memory devices of the plurality of memory devices, supplies a second chip select signal having an inactive state in common to third and fourth memory devices of the plurality of memory devices, supplies a first enable signal to the third memory device, and supplies a second enable signal to the fourth memory device, wherein the mode signal is not written to a first mode register of the third memory device and a second mode register of the fourth memory device.
23. The information processing system of claim 22 , wherein the active state is a high logic level and the inactive state is a low logic level.
24. The information processing system of claim 15 , wherein the data processing circuit processes read data, write data, or a combination thereof through a data terminal.
25. The information processing system of claim 15 , wherein the output circuit supplies an address signal, a chip select signal, a clock signal, or some combination thereof.