The MAX7347/MAX7348/MAX7349 I²C interfaced peripherals provide microprocessors with management of up to 64 key switches. Key inputs are monitored statically, not dynamically scanned, to ensure low-EMI operation. The MAX7347 can monitor up to 24 switches, the MAX7348 can monitor up to 40 switches, and the MAX7349 can monitor up to 64 switches. The switches can be metallic or resistive (carbon) up to 1kΩ.The key controller debounces and maintains a FIFO of key-press 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. The MAX7348/MAX7349 feature a tone generator to generate automatic key-click sounds or alarm tones under processor control.The sounder frequencies cover the 5th musical octave (523.25Hz to 987.77Hz), plus seven other musical notes up to 2637Hz. The output can also be programmed to be high or low for the sound duration to operate an electronic sounder, relay, or lamp.The MAX7347 is offered in 16-pin QSOP and TQFN packages. The MAX7348 is offered in a 20-pin QSOP package. The MAX7349 is available in 24-pin QSOP and TQFN packages. The MAX7347/MAX7348/MAX7349 operate over the -40°C to +125°C temperature range.ApplicationsIndustrial ControlsInstrumentation PanelsMedical InstrumentsSecurity and Access