Touch Interface - LG -T500 Service Manual

3. TECHNICAL BRIEF

3.14 Touch Interface

The touch controller is an analog interface circuit for a human interface touch screen device.
All of touch functions are composed of a register-based architecture and are controlled through the internal
register sets by serial interface.
Figure 3-14 Touch Driver Block Diagram
The SX8650 is designed for 4-wire resistive touch screen applications. The touch screen or touch panel is the
resistive sensor and can be activated by either a finger or stylus. The touch screen coordinates and touch
pressure are converted into I2C format by the SX8650 for transfer to the host.
The SX8650's channel pins (X+, X-, Y+, Y-) directly connect to standard touch screen X and Y resistive layers.
The SX8650 separately biases each of these layers and converts the resistive values into (X,Y) coordinates.
The channel pins are protected to VDD and GROUND.
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