Rainbow Electronics MAX7359 User Manual

General description, Applications, Features

General Description

The MAX7359 I

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 a small 24-pin TQFN (3.5mm x
3.5mm) package for cell phones, pocket PCs, and other
portable consumer electronic applications. The MAX7359
operates over the -40°C to +85°C temperature range.

Applications

Cell Phones

PDAs

Handheld Games

Portable Consumer Electronics

Features

♦ Optional Key Release Detection on All Keys
♦ Monitor Up to 64 Keys
♦ 1.62V to 3.6V Operation
♦ Autosleep and Autowake to Minimize Current

Consumption

♦ Under 1µA Sleep Current
♦ FIFO Queues Up to 16 Debounced Key Events
♦ Key Debounce Time User Configurable from 9ms

to 40ms

♦ Low-EMI Design Uses Static Matrix Monitoring
♦ Hardware Interrupt at the FIFO Level or at the End

of Definable Time Period

♦ Up to Seven Open-Drain Logic Outputs Available

Capable of Driving LEDs

♦ 400kbps, 5.5V-Tolerant, 2-Wire Serial Interface
♦ Selectable 2-Wire, Serial-Bus Timeout
♦ Four I

C Address Choices

♦ Small, 24-Pin TQFN Package (3.5mm x 3.5mm)

MAX7359

2-Wire Interfaced Low-EMI

Key Switch Controller/GPO

________________________________________________________________

Maxim Integrated Products

Ordering Information

19-0850; Rev 0; 7/07

EVALUATION KIT

AVAILABLE

PART

TEMP

RANGE

PIN-PACKAGE

PKG

CODE

MAX7359ETG+

-40

°C to

+85

°C

24 TQFN-EP*
(3.5mm x 3.5mm)

T243A3-1

Denotes a lead-free package.

EP = Exposed paddle.

MAX7359

COL_

GND

SCL

SDA

AD0

ROW_

SWITCH

ARRAY,

UP TO 64

SWITCHES

INPUT

1.62V TO 3.6V

INT

Typical Application Circuit

Pin Configuration appears at end of data sheet.

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.