Converter and driving method thereof

1. A converter for converting an input voltage into an output voltage, comprising:

a main switch; and

a switching controller, configured to control a switching operation of the main switch by using a first voltage corresponding to the output voltage and a first current flowing to the main switch, wherein

the switching controller is configured to determine a reference count according to the first voltage, and to determine a peak value of the first current corresponding to the reference count and a switching frequency of the main switch.

2. The converter of claim 1 , wherein the switching controller is configured

to compare the first voltage and a predetermined reference voltage, wherein the predetermined reference voltage is selected to control at least one of the switching frequency and the peak value of the first current;

to increase the reference count when the first voltage is greater than the reference voltage; and

to decrease the reference count when the first voltage is less than the reference voltage.

3. The converter of claim 2 , wherein the switching controller is configured to increase a center value of the reference count when the case in which the first voltage is sensed to be greater than the reference voltage is repeated at least twice; and

to decrease the center value of the reference count when the case in which the first voltage is sensed not to be greater than the reference voltage is repeated at least twice.

4. The converter of claim 3 , wherein the switching controller is configured to set a center count for controlling the center value of the reference count;

to decrease the center count when the first voltage is greater than the reference voltage; and

to increase the center count when the first voltage is less than the reference voltage.

5. The converter of claim 4 , wherein the switching controller is configured

to decrease the reference count when the center count is greater than a positive threshold value; and

to increase the reference count when the center count is less than a negative threshold value.

6. The converter of claim 3 , wherein the switching controller is configured

to determine the peak value of the first current according to the reference count.

7. The converter of claim 6 , wherein

the reference count is a value that corresponds to the time when the main switch performs a switching operation once; and

the switching frequency and the reference count are set according to a predetermined functional relationship.

8. The converter of claim 3 , wherein the switching controller comprises:

a first controller, configured

to compare the first current and the reference current and

to determine the turn-off of the main switch;

an output voltage detector, configured to detect the first voltage; and

a second controller, configured

to compare the first voltage and the reference voltage, and

to control the reference count.

9. The converter of claim 8 , wherein the first controller comprises:

a reference current generator, configured to determine a peak value of the first current corresponding to the reference count according to the functional relationship;

an oscillator, configured to generate clock signals;

a first counter, configured to receive the clock signals to generate the reference count, and to turn off the main switch when the reference count is greater than the number of clock signals corresponding to an on-time; and

a first comparator, configured to compare the reference current and the first current and to determine the turn-off of the main switch.

10. The converter of claim 8 , wherein the second controller comprises:

a second comparator, configured to compare the first voltage and the reference voltage, and to generate a bang-bang control signal according to the comparison result;

a second counter, configured to count the bang-bang control signal, and to generate information on the comparison result of the first voltage and the reference voltage; and

a corrector, configured to control the center value of the reference count according to the comparison result of the first voltage and the reference voltage, and to change the reference count according to the bang-bang control signal.

11. The converter of claim 1 , wherein the output voltage detector is configured:

to receive a gate control signal for controlling the main switch and an auxiliary voltage corresponding to the voltage at the main switch;

to set a sampling period for sampling the winding voltage; and

to set a voltage level of the winding voltage, that is sampled with the last pulse from among a first pulse string within the sampling period by using a plurality of pulse strings including the first pulse string and a second pulse string including a plurality of pulses, to be the first voltage.

12. The converter of claim 11 , further comprising

a voltage generator including a coil to which the auxiliary voltage is generated according to the voltage at the main switch.

13. The converter of claim 12 , wherein

the main switch is a transistor having a drain electrode and a source electrode and a gate electrode, configured to receive the gate control signal, and the first current corresponds to a drain-source current, flowing from the drain electrode to the source electrode.

14. The converter of claim 1 , wherein

the main switch and the switching controller are realized in a single chip.

15. A driving method of a converter including a main switch, for converting an input voltage into an output voltage according to a switching operation of the main switch, the driving method comprising the steps of

counting clock signals to generate a first count when the main switch is turned on;

comparing a first voltage, corresponding to the output voltage, and a reference voltage when the main switch is turned off, and changing a reference count according to the comparison result;

counting the number of times when the first voltage is greater than the reference voltage or the number of times when the first voltage is not greater than the reference voltage, and controlling the reference count according to the count result; and

determining a peak value of a first current flowing to the main switch corresponding to the reference count, and determining a switching frequency according to the reference count.

16. The driving method of claim 15 , wherein comparing of a first voltage and a reference voltage and changing of a reference count according to the comparison result comprises:

increasing the reference count when the first voltage is greater than the reference voltage; and

decreasing the reference count when the first voltage is less than the reference voltage.

17. The driving method of claim 16 , further comprising:

detecting the first voltage when the main switch is turned off;

turning on the main switch when the first count is greater than the reference count; and

increasing the first counter when the first count is less than the reference count.

18. The driving method of claim 15 , wherein controlling of the reference count according to the count result comprises

increasing a center value of the reference count when the first voltage is greater than the reference voltage at least twice, and decreasing the center value of the reference count when the first voltage is less than the reference voltage at least twice.

19. The driving method of claim 15 , wherein

determining of the peak value of the first current and determining of the switching frequency includes:

determining the peak value of the first current corresponding to the reference count by using a function for indicating a relationship of the reference count and the peak value of the first current, and determining the switching frequency by using a function for indicating a relationship of the reference count and the switching frequency.

20. The driving method of claim 15 , further comprising:

turning on the main switch, and comparing the first current and the peak value of the first current;

turning off the main switch when the first current is greater than a peak value of the first current according to the comparison result of the first current and the peak value of the first current; and

comparing and determining whether the first count is greater than the number of clock signals corresponding to the on time of the main switch when the first current is less than the peak value of the first current according to the comparison result of the first current and the peak value of the first current.