Chip for operating in multi power conditions and system having the same

1. An apparatus for controlling an I/O interface of a chip operated in multi-power conditions, comprising:

an enable signal generator for generating an enable signal based on a chip power down signal;

a reference voltage generator for generating a predetermined reference voltage in response to the enable signal;

a comparator for determining a voltage required for operating the chip by comparing an external power voltage with the reference voltage in response to the enable signal; and

an input/output means for performing an I/O interface function based on the voltage determined according to the comparison result of the comparator.

2. The apparatus of claim 1 , wherein the comparator stores the enable signal for a predetermined time and is turned off after the predetermined time.

3. The apparatus of claim 1 , wherein the enable signal is generated through an operation on the chip power down signal and a delay signal that the chip power down signal is delayed for a predetermined delay time, the enable signal being activated during the predetermined delay time.

4. The apparatus of claim 3 , wherein the enable signal generator includes an AND gate for performing a logic AND operation on the chip power down signal and an inverted delay signal of the chip power down signal.

5. The apparatus of claim 1 , wherein the comparator includes:

a first PMOS transistor of which a gate is controlled by the enable signal, the first PMOS transistor being connected between the power voltage and a first node;

a second PMOS transistor of which a gate is connected to a second node, the second PMOS transistor being connected to the first PMOS transistor in parallel;

a third PMOS transistor of which a gate is controlled by the enable signal, the third PMOS transistor being connected between the power voltage and the second node;

a fourth PMOS transistor of which a gate is connected to the first node, the fourth PMOS transistor being connected to the third PMOS transistor in parallel;

a first NMOS transistor receiving the external power voltage through a gate thereof, the first NMOS transistor being connected between the first node and the third node;

a second NMOS transistor receiving the reference voltage through a gate thereof, the second NMOS transistor being connected between the second node and the third node;

a third NMOS transistor of which a gate is controlled through the enable signal, the third NMOS transistor being connected between the third node and the ground voltage; and

an inverter for inverting a signal of the first node.

6. The apparatus of claim 5 , wherein the inverter includes a fifth PMOS transistor and a fourth NMOS transistor connected to each other in series between the power voltage and the ground voltage, the fifth PMOS transistor and the fourth NMOS transistor receiving the signal of the first node through each gate thereof.

7. The apparatus of claim 1 , wherein the reference voltage generator includes:

a first PMOS transistor of which a gate is controlled by the enable signal, the first PMOS transistor being connected between the power voltage and the first node;

a second PMOS transistor of which a gate is connected to the first node, the second PMOS transistor being connected between the power voltage and the first node;

a first NMOS transistor of which a gate is connected to the first node, the first NMOS transistor being connected between the first node and the second node;

a second NMOS transistor of which a gate is controlled by the enable signal, the second NMOS transistor being connected between the second node and the ground voltage;

a third PMOS transistor of which a gate is connected to the first node, the third PMOS transistor being connected between the power voltage and a third node through which the reference voltage is outputted;

a third NMOS transistor of which a gate is connected to the third node, the third NMOS transistor being connected between the third node and a fourth node; and

a fourth NMOS transistor of which a gate is connected to the fourth node, the fourth NMOS transistor being connected between the fourth node and the ground voltage.

8. A system comprising:

a power supplier for supplying a multi-power;

a first chip for operating using the power supplied from the power supplier; and

a second chip for comparing an internal reference voltage with the power supplied from the power supplier to determine a voltage for the first and the second chips, the second chip operating to interface with the first chip by using the determined voltage,

wherein the second chip includes:

an enable signal generator for generating an enable signal using a chip power down signal;

a reference voltage generator for generating a predetermined reference voltage in response to the enable signal;

a comparator for storing the enable signal for a predetermined time and determining a voltage required for operating the chip by comparing the reference voltage with an external power voltage in response to the enable signal during the predetermined time, the comparator being automatically turned off after a lapse of the predetermined time; and

an input/output means for performing an interface function using the voltage determined according to the comparison result of the comparator.

9. The system of claim 8 , wherein the enable signal is generated through an operation on the chip power down signal and a delay signal that the chip power down signal is delayed for a predetermined delay time, the enable signal being activated during the predetermined delay time.

10. The system of claim 9 , wherein the enable signal generator includes an AND gate for performing a logic AND operation on the chip power down signal and an inverted delay signal of the chip power down signal.

11. The system of claim 8 , wherein the comparator includes:

a first PMOS transistor of which a gate is controlled by the enable signal, the first PMOS transistor being connected between the power voltage and a first node;

a second PMOS transistor of which a gate is connected to a second node, the second PMOS transistor being connected to the first PMOS transistor in parallel;

a third PMOS transistor of which a gate is controlled by the enable signal, the third PMOS transistor being connected between the power voltage and the second node;

a fourth PMOS transistor of which a gate is connected to the first node, the fourth PMOS transistor being connected to the third PMOS transistor in parallel;

a first NMOS transistor receiving the external power voltage through a gate thereof, the first NMOS transistor being connected between the first node and the third node;

a second NMOS transistor receiving the reference voltage through a gate thereof, the second NMOS transistor being connected between the second node and the third node;

a third NMOS transistor of which a gate is controlled through the enable signal, the third NMOS transistor being connected between the third node and the ground voltage; and

an inverter for inverting a signal of the first node.

12. The system of claim 11 , wherein the inverter includes a fifth PMOS transistor and a fourth NMOS transistor connected to each other in series between the power voltage and the ground voltage, the fifth PMOS transistor and the fourth NMOS transistor receiving the signal of the first node through each gate thereof.

13. The system of claim 8 , wherein the reference voltage generator includes:

a first PMOS transistor of which a gate is controlled by the enable signal, the first PMOS transistor being connected between the power voltage and the first node;

a second PMOS transistor of which a gate is connected to the first node, the second PMOS transistor being connected between the power voltage and the first node;

a first NMOS transistor of which a gate is connected to the first node, the first NMOS transistor being connected between the first node and the second node;

a second NMOS transistor of which a gate is controlled by the enable signal, the second NMOS transistor being connected between the second node and the ground voltage;

a third PMOS transistor of which a gate is connected to the first node, the third PMOS transistor being connected between the power voltage and a third node through which the reference voltage is outputted;

a third NMOS transistor of which a gate is connected to the third node, the third NMOS transistor being connected between the third node and a fourth node; and

a fourth NMOS transistor of which a gate is connected to the fourth node, the fourth NMOS transistor being connected between the fourth node and the ground voltage.