The LM8333 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
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 low-power standby mode when there is
no keypad, I/O, or host activity.
The device is packaged in a 32–pin WQFN and a
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49-pin csBGA. Both are chip-scale packages.