Output circuit of semiconductor device and semiconductor device including thereof

1. An output circuit of a semiconductor device comprising:

a counter circuit that generates an ODT control signal;

a plurality of driver circuits having an ODT function;

a first selecting circuit that activates one of a plurality of ODT selection signals based on the ODT control signal;

a synchronizing circuit that synchronizes an activated ODT selection signal with a predetermined clock; and

a second selecting circuit that selects one or more driver circuits to be activated out of the plurality of driver circuits based on the activated ODT selection signal,

wherein the first selecting circuit is provided between the counter circuit and the synchronizing circuit, and the second selecting circuit is provided between the synchronizing circuit and the driver circuit.

2. The output circuit as claimed in claim 1 , wherein the counter circuit operates synchronously with the predetermined clock.

3. The output circuit as claimed in claim 2 , wherein the ODT control signal includes a first part indicating whether the ODT function is used or not, and a second part for selecting an ODT impedance.

4. The output circuit as claimed in claim 3 , wherein the counter circuit includes a first counter that generates the first part of the ODT control signal and a second counter that generates the second part of the ODT control signal, and a latency of the first counter is different from a latency of the second counter.

5. The output circuit as claimed in claim 3 , wherein the second part of the ODT control signal is activated during at least the write operation.

6. The output circuit as claimed in claim 1 , wherein the second selecting circuit selects one or more driver circuits to be activated out of the plurality of driver circuits, based on the activated ODT selection signal and a code signal for assigning an ODT impedance.

7. The output circuit as claimed in claim 1 , wherein at least a part of the plurality of driver circuits is also activated during a data read operation.

8. The output circuit as claimed in claim 1 , wherein an ODT impedance can be dynamically changed over between when the semiconductor device carries out a write operation and when other semiconductor device carries out a read operation or the write operation.

9. An output circuit of a semiconductor device that can dynamically change over between ODT impedances of a driver circuit, the output circuit comprising:

a first selecting circuit that selects any one ODT impedance group out of a plurality of ODT impedance groups;

a second selecting circuit that selects a predetermined ODT impedance out of the selected ODT impedance group; and

a synchronizing circuit that is provided between the first selecting circuit and the second selecting circuit and that controls the operation timing of the driver circuit,

wherein the first selecting circuit selects one ODT impedance group out of the plurality ODT impedance groups, based on the output of a counter that operates synchronously with the synchronizing circuit.

10. The output circuit as claimed in claim 9 , wherein the second selecting circuit selects a predetermined ODT impedance out of the selected ODT impedance group, based on the output of the synchronizing circuit and a code signal for assigning the ODT impedance.

11. The output circuit as claimed in claim 10 , wherein the code signal can be changed by a mode register set.

12. The output circuit as claimed in claim 9 , wherein the second selecting circuit further selects an output impedance of the driver circuit.

13. The output circuit as claimed in claim 9 , wherein the ODT impedance can be dynamically changed over between when the semiconductor device carries out the write operation and when other semiconductor device carries out the read operation or the write operation.

14. A semiconductor device having an output circuit, the output circuit comprising:

a counter circuit that generates an ODT control signal;

a plurality of driver circuits having an ODT function;

a first selecting circuit that activates one of a plurality of ODT selection signals based on the ODT control signal;

a synchronizing circuit that synchronizes an activated ODT selection signal with a predetermined clock; and

a second selecting circuit that selects one or more driver circuits to be activated out of the plurality of driver circuits based on the activated ODT selection signal,

wherein the first selecting circuit is provided between the counter circuit and the synchronizing circuit, and the second selecting circuit is provided between the synchronizing circuit and the driver circuit.

15. A data processing system comprising a data processor and a semiconductor memory device, wherein the semiconductor memory device includes an output circuit, the output circuit having:

a counter circuit that generates an ODT control signal;

a plurality of driver circuits having an ODT function;

a first selecting circuit that activates one of a plurality of ODT selection signals based on the ODT control signal;

a synchronizing circuit that synchronizes an activated ODT selection signal with a predetermined clock; and

a second selecting circuit that selects one or more driver circuits to be activated out of the plurality of driver circuits based on the activated ODT selection signal,

wherein the first selecting circuit is provided between the counter circuit and the synchronizing circuit, and the second selecting circuit is provided between the synchronizing circuit and the driver circuit.