MAX6955APL MAXIM [Maxim Integrated Products], MAX6955APL Datasheet

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MAX6955APL

Manufacturer Part Number
MAX6955APL
Description
2-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan
Manufacturer
MAXIM [Maxim Integrated Products]
Datasheet
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 I
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.
19-2548; Rev 0; 7/02
Pin Configurations and Typical Operating Circuits appear
at end of data sheet.
I
SPI is a trademark of Motorola, Inc.
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.
2
MAX6955AAX
MAX6955APL
C is a trademark of Philips Corp.
Set-Top Boxes
Panel Meters
White Goods
PART
2-Wire Interfaced, 2.7V to 5.5V LED Display
________________________________________________________________ Maxim Integrated Products
-40°C to +125°C
-40°C to +125°C
TEMP RANGE
Driver with I/O Expander and Key Scan
Ordering Information
General Description
Automotive
Bar Graph Displays
Audio/Video Equipment
Applications
PIN-PACKAGE
36 SSOP
40 PDIP
2
C™-compati-
o 400kbps 2-Wire Interface Compatible with I
o 2.7V to 5.5V Operation
o Drives Up to 16 Digits 7-Segment, 8 Digits
o Drives Common-Cathode Monocolor and Bicolor
o Built-In ASCII 104-Character Font for 14-Segment
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-
o IRQ Output when a Key Input is Debounced
o 36-Pin SSOP and 40-Pin DIP Packages
o Automotive Temperature Range Standard
14-Segment, 8 Digits 16-Segment, 128 Discrete
LEDs, or a Combination of Digit Types
LED Displays
and 16-Segment Digits and Hexadecimal Font for
7-Segment Digits
Switch Reader to Scan and Debounce Up to 32
Switches with n-Key Rollover
OSC_OUT
BLINK
ISET
OSC
SDA
SCL
AD0
AD1
COUNTER
NETWORK
DIVIDER/
CURRENT
SOURCE
CONTROL
BLINK
RAM
2-WIRE SERIAL INTERFACE
Functional Diagram
MAX6955
AND KEY-SCAN
MULTIPLEXER
BRIGHTNESS
CONTROL
CONTROL
DIGIT
PWM
GPIO
CONFIGURATION
CHARACTER
GENERATOR
REGISTER
ROM
DRIVERS
LED
Features
P0 TO P4
O0 TO O18
2
C
1

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MAX6955APL Summary of contents

Page 1

... Bar Graph Displays White Goods Audio/Video Equipment Ordering Information PART TEMP RANGE MAX6955AAX -40°C to +125°C MAX6955APL -40°C to +125°C Pin Configurations and Typical Operating Circuits appear at end of data sheet trademark of Philips Corp. SPI is a trademark of Motorola, Inc. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’ ...

Page 2

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan ABSOLUTE MAXIMUM RATINGS Voltage (with Respect to GND) V+ .........................................................................-0.3V to +6V SCL, SDA, AD0, AD1 ...........................................-0.3V to +6V All Other Pins............................................-0.3V to (V+ + 0.3V) ...

Page 3

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan DC ELECTRICAL CHARACTERISTICS (continued) (Typical Operating Circuit 2.7V to 5.5V, T PARAMETER SYMBOL Segment Drive Source Current ∆I Segment Current Slew Rate Segment Drive ...

Page 4

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan TIMING CHARACTERISTICS (Typical Operating Circuit 2.7V to 5.5V, T PARAMETER SYMBOL TIMING CHARACTERISTICS Serial Clock Frequency Bus Free Time Between a STOP and a ...

Page 5

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan (V+ = 3.3V, LED forward voltage = 2.4V, Typical Application Circuit, T INTERNAL OSCILLATOR FREQUENCY vs. TEMPERATURE 4 56kΩ SET C = 22pF SET ...

Page 6

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan PIN NAME SSOP PDIP General-Purpose I/O Ports (GPIOs). GPIO can be configured as logic inputs or open-drain outputs. Enabling key scanning configures ...

Page 7

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan 1dp 1d Figure 1. Segment Labeling for 7-Segment Display, 14-Segment Display, and 16-Segment Display Table 1. MAX6955 Drive ...

Page 8

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 2. Connection Scheme for Eight 16-Segment Digits DIGIT CCO — — CC1 ...

Page 9

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan SDA t SU, DAT t LOW SCL t HIGH t HD, STA START CONDITION Figure 2. 2-Wire Serial Interface Timing Details SDA ...

Page 10

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 5. MAX6955 Address Map PIN CONNECTION DEVICE ADDRESS AD1 AD0 GND GND GND GND SDA ...

Page 11

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan segment fonts (Tables 8 and 9). The lower 7 bits of the digit data (D6 to D0) select the character from the font. The most significant ...

Page 12

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Multiplex Clock and Blink Timing The OSC pin can be fitted with capacitor C to use the internal RC multiplex oscillator, or driven by an external ...

Page 13

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 7. Register Address Map REGISTER No-Op Decode Mode Global Intensity Scan Limit Configuration GPIO Data Port Configuration Display Test Write KEY_A Mask Read KEY_A Debounce ...

Page 14

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 7. Register Address Map (continued) REGISTER Digit 4a Plane P0 (7 Segment Only) Digit 5a Plane P0 (7 Segment Only) Digit 6a Plane P0 (7 ...

Page 15

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 7. Register Address Map (continued) REGISTER Write Digit 2a Planes P0 and P1 with Same Data (7 Segment Only), Reads as 0x00 Write Digit 3a ...

Page 16

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION ACKNOWLEDGE FROM MAX6955 S SLAVE ADDRESS Figure 7. Command Byte Received HOW CONTROL BYTE AND DATA BYTE ...

Page 17

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan 200µs DIGIT 0 DIGIT 0 CATHODE DRIVER INTENSITY SETTINGS 1/16TH HIGH-Z (MIN ON) 2/16TH LOW 3/16TH LOW 4/16TH LOW 5/16TH LOW 6/16TH LOW 7/16TH LOW 8/16TH ...

Page 18

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan LED OUTPUT O0 LED OUTPUT O1 LED OUTPUT O2 LED OUTPUT O3 LED OUTPUT O4 LED OUTPUT O5 LED OUTPUT O6 LED OUTPUT ...

Page 19

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Key Debounced Registers The Key_A debounced, Key_B debounced, Key_C debounced, and Key_D debounced read-only registers (Table 35) show which keys have been detected as debounced by ...

Page 20

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Choosing Supply Voltage to Minimize Power Dissipation The MAX6955 drives a peak current of 40mA into LEDs with a 2.2V forward-voltage drop when operated from a ...

Page 21

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 8. 16-Segment Display Font Map MSB x000 x001 x010 x011 x100 LSB 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 ...

Page 22

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 10. Digit Plane Data Register Format MODE 14-segment or 16-segment mode, writing digit data to use font map data with decimal place unlit 14-segment or ...

Page 23

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 12. 7-Segment Segment Mapping Decoder for Hexadecimal Font 7-SEGMENT CHARACTER D6, D5, D7 — — — — ...

Page 24

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 14. Example Configurations for Display Digit Combinations DIGIT-TYPE REGISTER SETTING CODE (HEX) Digits are 16-segment or 7- segment digits. Digit 0 is ...

Page 25

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 16. Initial Power-Up Register Status POWER-UP REGISTER CONDITION Decode Mode Decode mode enabled Global Intensity 1/16 (min on) Scan Limit Display 8 digits ...

Page 26

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 17. Configuration Register Format REGISTER DATA MODE Configuration Register Table 19. Blink Rate Selection (B Data Bit ...

Page 27

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 24. Global Intensity (I Data Bit D6) Format MODE Intensity for all digits is controlled by one setting in the global intensity register. Intensity for ...

Page 28

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 28. Individual Segment Intensity Registers REGISTER ADDRESS FUNCTION CODE (HEX) Intensity10 Register 0x10 Intensity32 Register 0x11 Intensity54 Register 0x12 Intensity76 Register 0x13 Intensity10a Register 0x14 ...

Page 29

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 30. Odd Individual Segment Intensity Format TYPICAL DUTY SEGMENT CYCLE CURRENT (mA) 1/16 (min on) 2.5 2/16 5 3/16 7.5 4/16 10 5/16 12.5 6/16 ...

Page 30

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 33. Port Configuration Register Format ADDRESS MODE CODE (HEX) GPIO 0x06 Configuration Register PORT ALLOCATION OPTIONS 0 Keys Scanned 0x06 8 Keys Scanned 0x06 16 ...

Page 31

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 35. Key Debounced Register Format (Read Only) KEY ADDRESS DEBOUNCED CODE REGISTER (HEX) Key_A Debounced 0x08 SW_A7 Register Key_B Debounced 0x09 SW_B7 Register Key_C Debounced ...

Page 32

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 38. Slot 1 Configuration ...

Page 33

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 39. Slot 2 Configuration ...

Page 34

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 40. Slot 3 Configuration ...

Page 35

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 41. Slot 4 Configuration ...

Page 36

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan 3. 47µF 100nF GND GND GND MAX6955 SCL AD0 AD1 SDA BLINK OSC_OUT OSC ISET C SET R SET ...

Page 37

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan 3. 47µF 100nF GND GND GND MAX6955 SCL SCL AD0 AD0 AD1 AD1 SDA SDA BLINK OSC_OUT OSC ISET C SET R SET ...

Page 38

... AD0 33 OSC_OUT 4 SDA 32 BLINK 5 SCL 31 O18 6 AD1 30 O17 7 O0 O16 O15 O14 10 O3 MAX6955APL 26 O13 O12 O11 O10 N. OSC GND GND 18 ISET 19 SSOP GND 20 Pin Configurations ...

Page 39

Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information www.maxim-ic.com/packages.) Maxim cannot assume ...

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