The LM8333GGR8AXS/NOPB Mobile I/O Companion 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 × 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 LM8333GGR8AXS/NOPB automatically enters a low-power standby mode when there is no keypad, I/O, or host activity.
The device is packaged in a 32–pin WQFN and a49-pin csBGA. Both are chip-scale packages.
Feature
- 8 × 8 Standard Keys
- 8 Special Function Keys (SF Keys) Providing a Total of 72 Keys for the Maximum Keyboard Matrix
- ACCESS.Bus (I2C-compatible) Communication Interface to the Host
- Four General Purpose Host Programmable I/O Pins with Two Optional (Slow) External Interrupts
- 15-byte FIFO Buffer to Store Key Pressed and Key Released Events
- Error Control with Error Reports on (FIFO Overrun, Keypad Overrun, Invalid Command)
- Host Programmable PWM
- Host Programmable Active Time and Debounce Time
