MAX7347 Datasheet, PDF (1/29 Pages) Maxim Integrated Products – 2-Wire Interfaced Low-EMI Key Switch and Sounder Controllers

19-3556; Rev 5; 5/07
EVAALVUAAILTAIOBNLEKIT
2-Wire Interfaced Low-EMI Key Switch
and Sounder Controllers
General Description
The MAX7347/MAX7348/MAX7349 I²C interfaced periph-
erals 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 (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 pro-
grammed 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.
Applications
Medical Instruments
Instrumentation Panels
Security and Access
Industrial Controls
Pin Configurations appear at end of data sheet.
Typical Application Circuit
INPUT
2.4V TO 3.6V
MAX7349
V+
COL_
SCL
SDA
ALERT
INT
AD0
GND
ROW_
SOUNDER
8
SWITCH
ARRAY, UP
8
TO 64
SWITCHES
PIEZO
TRANSDUCER
Features
♦ 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
♦ Four I²C Address Choices
♦ Selectable 2-Wire Serial Bus Timeout
♦ Under 10µA Shutdown Current
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
MAX7347AEE+ -40°C to +125°C 16 QSOP
MAX7347ATE+ -40°C to +125°C 16 TQFN-EP*
MAX7348AEP+ -40°C to +125°C 20 QSOP
MAX7349AEG+ -40°C to +125°C 24 QSOP
MAX7349ATG+ -40°C to +125°C 24 TQFN-EP*
+Denotes lead-free package.
*EP = Exposed paddle.
PKG
CODE
E16-4
T1644-4
E20-1
E24-1
T2444-4
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.