General Description
The MAX7359 I
2
C interfaced peripheral provides micro-
processors 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 5kΩ of resistance.
The MAX7359 features autosleep and autowake to fur-
ther 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 (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 INT, if not used, can function as a general-pur-
pose output (GPO).
The MAX7359 is offered in small, 24-pin TQFN (3.5mm x
3.5mm) and 25-bump WLP (2.31mm x 2.31mm) pack-
ages for cell phones, pocket PCs, and other portable
consumer electronic applications. The MAX7359 oper-
ates over the -40°C to +85°C temperature range.
Applications
Cell Phones
PDAs
Handheld Games
Portable Consumer Electronics
Features
o Optional Key Release Detection on All Keys
o Monitor Up to 64 Keys
o +1.62V to +3.6V Operation
o Autosleep and Autowake to Minimize Current
Consumption
o Under 1µA Sleep Current
o FIFO Queues Up to 16 Debounced Key Events
o Key Debounce Time User Configurable from 9ms
to 40ms
o Low-EMI Design Uses Static Matrix Monitoring
o Hardware Interrupt at the FIFO Level or at the End
of Definable Time Period
o Up to Seven Open-Drain Logic Outputs Available
Capable of Driving LEDs
o 400kbps, 5.5V-Tolerant, 2-Wire Serial Interface
o Selectable 2-Wire, Serial-Bus Timeout
o Four I
2
C Address Choices
o Small, 24-Pin TQFN Package (3.5mm x 3.5mm) , or
25-Pin WLP Package (2.31mm x 2.31mm)
MAX7359
2-Wire Interfaced Low-EMI
Key Switch Controller/GPO
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-0850; Rev 4; 6/10
EVALUATION KIT
AVAILABLE
N.C.
I.C.
*EP = EXPOSED PAD.
