By Maxim Integrated 21
Maxim's MAX7359 I2C-interfaced peripheral provides microprocessors with management of up to 64 key switches. Key codes are generated for each press and release of a key for easier implementation of multiple key entries. Key inputs are monitored statically, not dynamically, to ensure low-EMI operation. The switches can be metallic or resistive (carbon) with up to 5 kΩ of resistance.
The MAX7359 features autosleep and autowake to further minimize the power consumption of the device. The autosleep feature puts the device in a low-power state (1µA typ) after a sleep timeout period. The autowake feature configures the MAX7359 to return to normal operating mode from sleep upon a key press.
The key controller debounces and maintains a FIFO of key-press and release events (including autorepeat, if enabled). An interrupt (active-low INT) output can be configured to alert key presses either as they occur, or at maximum rate.
Any of the column drivers (COL2/PORT2–COL7/PORT7) or the active-low INT, if not used, can function as a general-purpose output (GPO).
The MAX7359 is offered in small, 24-pin TQFN (3.5 mm x 3.5 mm) and 25-bump WLP (2.31 mm x 2.31 mm) packages for cell phones, pocket PCs, and other portable consumer electronic applications. The MAX7359 operates over the -40°C to +85°C temperature range.