MAX6955 Datasheet, PDF (1/39 Pages) Maxim Integrated Products – 2-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan

19-2548; Rev 0; 7/02
EVAALVUAAILTAIOBNLEKIT
2-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
General Description
The MAX6955 is a compact display driver that interfaces
microprocessors to a mix of 7-segment, 14-segment,
and 16-segment LED displays through an I²C™-compati-
ble 2-wire serial interface. The MAX6955 drives up to 16
digits 7-segment, 8 digits 14-segment, 8 digits 16-seg-
ment, or 128 discrete LEDs, while functioning from a
supply voltage as low as 2.7V. The driver includes five
I/O expander or general-purpose I/O (GPIO) lines, some
or all of which can be configured as a key-switch reader.
The key-switch reader automatically scans and
debounces a matrix of up to 32 switches.
Included on chip are full 14- and 16-segment ASCII
104-character fonts, a hexadecimal font for 7-segment
displays, multiplex scan circuitry, anode and cathode
drivers, and static RAM that stores each digit. The max-
imum segment current for the display digits is set using
a single external resistor. Digit intensity can be inde-
pendently adjusted using the 16-step internal digital
brightness control. The MAX6955 includes a low-power
shutdown mode, a scan-limit register that allows the
user to display from 1 to 16 digits, segment blinking
(synchronized across multiple drivers, if desired), and a
test mode, which forces all LEDs on. The LED drivers
are slew-rate limited to reduce EMI.
For an SPI™-compatible version, refer to the MAX6954
data sheet. An evaluation kit* (EV kit) for the MAX6955
is available.
*Future product—contact factory for availability.
Features
o 400kbps 2-Wire Interface Compatible with I²C
o 2.7V to 5.5V Operation
o Drives Up to 16 Digits 7-Segment, 8 Digits
14-Segment, 8 Digits 16-Segment, 128 Discrete
LEDs, or a Combination of Digit Types
o Drives Common-Cathode Monocolor and Bicolor
LED Displays
o Built-In ASCII 104-Character Font for 14-Segment
and 16-Segment Digits and Hexadecimal Font for
7-Segment Digits
o Automatic Blinking Control for Each Segment
o 10µA (typ) Low-Power Shutdown (Data Retained)
o 16-Step Digit-by-Digit Digital Brightness Control
o Display Blanked on Power-Up
o Slew-Rate-Limited Segment Drivers for Lower EMI
o Five GPIO Port Pins Can Be Configured as Key-
Switch Reader to Scan and Debounce Up to 32
Switches with n-Key Rollover
o IRQ Output when a Key Input is Debounced
o 36-Pin SSOP and 40-Pin DIP Packages
o Automotive Temperature Range Standard
Functional Diagram
Set-Top Boxes
Panel Meters
White Goods
Applications
Automotive
Bar Graph Displays
Audio/Video Equipment
PART
MAX6955AAX
MAX6955APL
Ordering Information
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
36 SSOP
40 PDIP
Pin Configurations and Typical Operating Circuits appear
at end of data sheet.
I²C is a trademark of Philips Corp.
SPI is a trademark of Motorola, Inc.
ISET
CURRENT
SOURCE
OSC
OSC_OUT
DIVIDER/
COUNTER
NETWORK
GPIO
AND KEY-SCAN
CONTROL
PWM
BRIGHTNESS
CONTROL
DIGIT
MULTIPLEXER
P0 TO P4
LED
DRIVERS
O0 TO O18
MAX6955
CHARACTER
GENERATOR
ROM
BLINK
BLINK
CONTROL
CONFIGURATION
RAM
REGISTER
SCL
AD0
2-WIRE SERIAL INTERFACE
AD1
SDA
________________________________________________________________ Maxim Integrated Products 1
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1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.