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 1k.
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.
Key Features
Applications/Uses
400kbps, 5.5V-Tolerant 2-Wire Serial Interface
2.4V to 3.6V Operation
Monitor Up to 64 Keys (MAX7349), 40 Keys (MAX7348), or 24 Keys (MAX7347)
FIFO Queues Up to 8 Debounced Key Events
Key Debounce Time User Configurable from 9ms to 40ms
Key Autorepeat Rate and Delay User Configurable
Low-EMI Design Uses Static Matrix Monitoring
Hardware Interrupt on Each Debounced Event or FIFO Level, or at End of Definable Time Period
Up to Six Open-Drain Logic Outputs Available Capable of Driving LEDs
Sounder Output Generates Automatic Key Clicks
14 Programmable Musical Sounder Frequencies
Continuous or Programmable Sounder Duration
Easy Automatic Single-Tone and Dual-Tone Alarm Sound Generation
Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in
U.S. dollars and subject to change. Quantity pricing may vary
substantially and international prices may differ due to local
duties, taxes, fees, and exchange rates. For volume-specific prices
and delivery, please see the price and availability page
or contact an authorized distributor.
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