Patent ID: 8279196

Claim:
A power-down display device, comprising: a surface capacitive touch panel for inputting a contact of an object; a first clock generator for generating a first clock signal; and a touch panel controller comprising: a second clock signal generator for generating a second clock signal; a multiplexer coupled to the first clock signal and the second clock signal; a phase lock loop coupled to the multiplexer and the first clock generator, for multiplying the first clock signal in frequency when the display device operates in a normal mode; a signal generator coupled to the surface capacitive touch panel, for generating a sensing signal when the object contacts the surface capacitive touch panel; a current detector coupled to the surface capacitive touch panel, for generating a sensing current when the object contacts the surface capacitive touch panel; a current-voltage converter for converting the sensing current to a sensing voltage; an analog-to-digital converter for converting the sensing voltage to a digital data signal; and a touch-position calculator for calculating a touch position on the surface capacitive touch panel based on the digital data signal, wherein when the display device operates in the normal mode, the multiplexer switches to the first clock generator and the phase lock loop to output the first clock signal, and when the display device operates in a power-down mode, the multiplexer switches to the second clock generator to output the second clock signal, and the phase lock loop, the first clock generator, the analog-to-digital converter, and the touch-position calculator are turned off.