LM8500 Datasheet | National Semiconductor

Description The LM8300/8400/8500 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: Device LM8300 LM8400 LM8500 Operating Voltage 3, 5 V 3, 5 V 5V Brownout Voltage 2.7 to 2.9 V No Brownout 4.17V to 4.5V Operating Frequency 3.27 MHz 3.27 MHz 3.27, 10 MHz I/O Pins 18 18 18 Packages 44 LLP, 44 PLCC, 48 TSSOP 44 LLP, 44 PLCC, 48 TSSOP 44 LLP, 44 PLCC, 48 TSSOP Temperature 0˚C to +70˚C 0˚C to +70˚C 0˚C to +70˚C self-power down mode, the current drawn is typically less than 2 µA. The device resumes normal operation when a touch is detected on the touch screen or munication 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. Features KEY FEATURES n Supports 4 wire resistive touch panels n Low power standby current typically less than 2 µA at 5.5V n Maximum speed of 500 coordinate pairs per second n Automatic wake up and return to standby n 10 bit A/D n On-chip touch screen current drivers - no external driver required n UART interface n Controller configurations are stored in the internal non-volatile storage element n Touch pressure can be measured APPLICATIONS n Personal Digital Assistants n Smart Hand-Held Devices n Touch Screen Monitors n Point-of-Sales Terminals n KIOSK n Pagers n Cell...