DISPLAY DRIVER IC HAVING EMBEDDED MEMORY
A display driver IC for controlling display of an image on a display panel is provided with a memory and a switch circuit. The memory, in which digital data corresponding to the image is stored, operates with a first voltage. The switch circuit turns ON and OFF supply of the first voltage to the memory. The switch circuit operates with a second voltage that is higher than the first voltage.
1 . A display driver IC for controlling display of an image on a display panel, comprising:
a memory configured to operate with a first voltage, in which digital data corresponding to said image is stored; and
a switch circuit configured to operate with a second voltage that is higher than said first voltage and to turn ON and OFF supply of said first voltage to said memory.
2 . The display driver IC according to claim 1 , further comprising:
a power supply circuit configured to generate a third voltage that is higher than said first voltage; and
a driver circuit configured to convert said digital data into a gray-scale voltage by using said third voltage and to output said gray-scale voltage to said display panel,
wherein electric power is supplied to said switch circuit from said power supply circuit.
3 . The display driver IC according to claim 2 , further comprising a buffer circuit provided between said power supply circuit and said switch circuit and configured to convert said third voltage into said second voltage.
4 . The display driver IC according to claim 2 ,
wherein a memory cell in said memory has a first transistor configured to operate with said first voltage,
said switch circuit has a second transistor having a gate to which said second voltage is applied and configured to output said first voltage to said memory, and
said driver circuit has a third transistor configured to output said gray-scale voltage,
wherein a breakdown voltage of said second transistor is equal to a breakdown voltage of said third transistor.
5 . The display driver IC according to claim 4 ,
wherein said second transistor has a same structure as said third transistor.
6 . The display driver IC according to claim 4 , further comprising a well voltage control circuit,
wherein at a time of a standby mode, said well voltage control circuit applies a fourth voltage that is a negative voltage to a well on which said first transistor is formed,
wherein said power supply circuit includes:
a positive voltage power supply configured to generate said third voltage that is a positive voltage; and
a negative voltage power supply configured to generate a fifth voltage that is a negative voltage,
wherein said driver circuit converts said digital data into said gray-scale voltage by using a voltage range defined by said third voltage and said fifth voltage,
wherein said fourth voltage is generated from said fifth voltage generated by said negative voltage power supply.
7 . The display driver IC according to claim 6 ,
wherein said well voltage control circuit has a fourth transistor configured to output said fourth voltage, and a breakdown voltage of said fourth transistor is equal to a breakdown voltage of said third transistor.
8 . The display driver IC according to claim 7 ,
wherein said fourth transistor has a same structure as said third transistor.
9 . The display driver IC according to claim 1 ,
wherein said switch circuit controls supply of said first voltage to said memory separately with respect to each of regions in said memory.
10 . The display driver IC according to claim 1 ,
wherein said memory includes a memory cell and a peripheral circuit,
wherein said switch circuit controls supply of said first voltage to said memory cell and supply of said first voltage to said peripheral circuit separately from each other.