LM8400

The LM8400 is a 4-wire resistive touch screen controller. The controller samples and drives the touch screen without the need of any external hardware.

The built in 10-bit A/D provides a maximum of 500 coordinate pairs per second (cpps). The data sampled from the touch screen is sent out on the UART at a speed of 38400 bps.

The controller has a power-saving mode which causes the controller to self-power down when no touch is detected on the touch screen for a specified amount of time. In the Devices included in this datasheet: self-power down mode, the current drawn is typically less than 2 µA.

The LM8400 resumes normal operation when a touch is detected on the touch screen or communication is detected on the UART. In addition to the self-power down mode, the controller can be disabled by pulling the SHUTDOWN pin low. The controller resumes normal operation when the SHUTDOWN pin is tristated or pulled high.

The controller has an internal non-volatile memory storage element to store configuration data such as calibration points or controller configurations.