Current range control circuit, data driver, and organic light emitting display

1. An organic light emitting display comprising:

a scan driver for sequentially applying scan signals to scan lines;

a data driver for applying data currents to data lines, a range of the data currents being proportionally increased and decreased by current range control signals; and

a pixel portion for displaying images in response to the scan signals and the data currents.

2. The organic light emitting display of claim 1 , wherein a scan driver control signal is transmitted to the scan driver.

3. An organic light emitting display comprising,

a scan driver for sequentially applying scan signals to scan lines;

a data driver for applying data currents to data lines, a range of the data currents being proportionally increased or decreased by current range control signals; and

a pixel portion for displaying images in response to the scan signals and the data currents,

wherein data signals are supplied to the data driver, the data signals including video data being supplied to the organic light emitting display, and

wherein the data driver includes:

a shift register for outputting a latch control signal in response to a clock signal and a synchronizing signal;

a data latch for sequentially receiving the video data in response to a latch control signal and for outputting the video data in parallel as parallel video data;

a digital to analog converter for converting the parallel video data into analog currents and for outputting the analog currents; and

a current range control circuit for receiving the analog currents and the current range control signals and for outputting the data currents proportional to the analog currents to the pixel portion.

4. The organic light emitting display of claim 3 ,

wherein values of the data currents are proportional to values of the analog currents output from the digital to analog converter through proportionality constants, and

wherein the current range control signals determine the proportionality constants.

5. The organic light emitting display of claim 3 , wherein the current range control circuit comprises:

a current mirror circuit including a first transistor, the first transistor having a first transistor source, a first transistor drain, and a first transistor gate, and second transistors coupled to the first transistor, each of the second transistors forming a current mirror with the first transistor; and

a switching circuit for selectively transmitting drain currents of the second transistors in response to the current range control signals to obtain transmitted drain currents and adding together the transmitted drain currents to obtain each one of the data currents.

6. The organic light emitting display of claim 5 , wherein the current range control circuit further comprises a negative feedback circuit for making a drain voltage of the first transistor equal to drain voltages of the second transistors.

7. The organic light emitting display of claim 6 , wherein the negative feedback circuit comprises:

third transistors having sources coupled to the second transistors and having drains coupled to the switching circuit to transmit the drain currents of the second transistors to the switching circuit; and

an operational amplifier having a positive input port, a negative input port, and an output port, the positive input port being coupled to the first transistor drain, the negative input port being coupled to a drain of one of the second transistors, and the output port being coupled to gates of the third transistors.

8. The organic light emitting display of claim 7 , wherein the negative feedback circuit further comprises a capacitor coupled between the output port and the negative input port of the operational amplifier.

9. The organic light emitting display of claim 5 ,

wherein the analog currents output from the digital to analog converter are applied to the first transistor drain,

wherein the first transistor drain and the first transistor gate are electrically coupled to each other,

wherein gates of the second transistors are electrically coupled to the first transistor gate, and

wherein sources of the second transistors are electrically coupled to the first transistor source.

10. The organic light emitting display of claim 5 ,

wherein the switching circuit comprises fourth transistors, each of the fourth transistors corresponding to one of the second transistors,

wherein the drain currents of the second transistors are applied to sources of corresponding ones of the fourth transistors,

wherein the current range control signals are applied to gates of the fourth transistors, and

wherein drains of the fourth transistors are coupled to one another to output the data currents.

11. The organic light emitting display of claim 5 ,

wherein the switching circuit comprises fourth transistors, each of the fourth transistors corresponding to one of the second transistors,

wherein the drain currents of the second transistors are applied to sources of a corresponding one of the fourth transistors,

wherein a first voltage is applied to a gate of one transistor among the fourth transistors to turn on the one transistor,

wherein the current range control signals are applied to gates of remaining transistors among the fourth transistors, and

wherein drains of the fourth transistors are coupled together to output the data currents.