LM8333 Datasheet | National Semiconductor

Description The LM8333 is a general-purpose controller for matrixaddressed keypads which provides an ACCESS.bus (I2Cpatible) interface to a host microcontroller. It offloads the burden of keyboard scanning from the host, while providing extremely low power consumption in both operational and standby modes. It supports keypad matrices up to 8 x 8 in size (plus another 8 special-function keys), for portable applications such as cellphones, PDAs, games, and other handheld applications. Key press and release events are encoded into a byte format and loaded into a FIFO buffer for retrieval by the host processor. An interrupt output (IRQ) is used to signal events such as keypad activity, a state change on either of two interrupt-capable general-purpose I/O pins, or an error condition. Interrupt and error codes are available to the host by reading dedicated registers. Four general-purpose I/O pins are available, two of which have interrupt capability. A pulse-width modulated output based on a host-programmable internal timer is also available, which can be used as a general-purpose output if the PWM function is not required. To minimize power, the LM8333 automatically enters a lowpower standby mode when there is no keypad, I/O, or host activity. The device is packaged in a 49-pin MICRO-ARRAY chipscale package. 2.0 Features n 8 x 8 standard keys n 8 special function keys (SF keys) providing a total of 72 keys for the maximum keyboard matrix n ACCESS.bus (I2C-patible) munication interface to the host n Four general purpose host programmable I/O pins with two optional (slow) external Interrupts n 16 byte FIFO buffer to store key pressed and key released events n Error control with error reports on (FIFO overrun, Keypad overrun, invalid mand) n Host programmable PWM n Host programmable active time and debounce time 3.0 Block Diagram © 2006 National Semiconductor Corporation DS202106 .national. Data Sheet 4 U . .. 4.0 Pin Assignments Top...