Patent ID: 8723807

Claim:
A combined touch sensor and light-emitting-diode (LED) driver, comprising: an integrated circuit having a shared port, the integrated circuit comprising: a capacitance-to-digital converter (CDC) circuit configured to detect a touch, the CDC circuit coupled to the shared port and configured to operate with a first operating voltage, the CDC circuit comprising: an integrator; a reference capacitor coupled to a predetermined voltage; and a first switch coupled in series to the reference capacitor to connect or disconnect the reference capacitor to or from the integrator according to a first clock signal; an LED driver circuit configured to drive an LED if the LED is coupled to the shared port, the LED driver circuit also coupled to the shared port and configured to operate with a second operating voltage that is higher than the first operating voltage; and an n-type field effect transistor connected in series between the shared port and the CDC circuit.