Datasheet

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● Set-Top Boxes

● Panel Meters

● White Goods

● Bar Graph Displays

● Audio/Video Equipment

General Description

The MAX6954 is a compact display driver that inter-

faces microprocessors to a mix of 7-segment, 14-seg-

ment, and 16-segment LED displays through an SPI-/

QSPI™-compatible 4-wire serial interface. The serial

interface may be cascaded through multiple devices.

The MAX6954 drives up to 16 digits 7-segment, 8 dig-

its 14-segment, 8 digits 16-segment, or 128 discrete

LEDs, while functioning from a supply voltage as low as

2.7V. The driver includes five I/O expander (or GPIO)

lines, some or all of which may be configured as

a key-switch reader, which 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 driv-

ers, and static RAM that stores each digit. The maximum

segment current for the display digits is set using a single

external resistor. Digit intensity can be independently

adjusted using the 16-step internal digital brightness con-

trol. The MAX6954 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 mul-

tiple drivers, if desired), and a test mode, which forces all

LEDs on. The LED drivers are slew-rate limited to reduce

EMI.

For a 2-wire interfaced version, refer to the MAX6955

data sheet. An evaluation kit (EV kit) for the MAX6955 is

available.

Applications

Features

● High-Speed 26MHz SPI/QSPI/MICROWIRE

Compatible Serial Interface

● 2.7V to 5.5V Operation

● Drives Up to 16 Digits 7-Segment, 8 Digits

14-Segment, 8 Digits 16-Segment, 128 Discrete

LEDs, or a Combination of Digit Types

● Drives Common-Cathode Monocolor and Bicolor LED

Displays

● Built-In ASCII 104-Character Font for 14-Segment

and 16-Segment Digits and Hexadecimal Font for

7-Segment Digits

● Automatic Blinking Control for each Segment

● 10µA (typ) Low-Power Shutdown (Data Retained)

● 16-Step Digit-by-Digit Digital Brightness Control

● Display Blanked on Power-Up

● Slew-Rate Limited Segment Drivers for Lower EMI

● Five GPIO Port Pins Can Be Configured as Key-

Switch Reader to Scan and Debounce Up to 32

Switches with n-Key Rollover

● IRQ Output when a Key Input Is Debounced

● 36-Pin SSOP and 40-Pin DIP and TQFN Packages

● Automotive Temperature Range Standard

+Denotes a lead-free/RoHS-compliant package.

*EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

MAX6954AAX -40°C to +125°C 36 SSOP

MAX6954APL -40°C to +125°C 40 PDIP

MAX6954ATL+ -40°C to +125°C 40 TQFN-EP*

ISET

OSC

OSC_OUT

BLINK

CLK

DIN

DOUT

4-WIRE SERIAL INTERFACE

RAM

BLINK

CONTROL

CONFIGURATION

CHARACTER

GENERATOR

ROM

CURRENT

SOURCE

DIVIDER/

COUNTER

NETWORK

DIGIT

MULTIPLEXER

PWM

BRIGHTNESS

CONTROL

GPIO

AND KEY-SCAN

CONTROL

LED

DRIVERS

O0 TO O23

P0 TO P4

MAX6954

MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display

Driver with I/O Expander and Key Scan

19-2460; Rev 5; 7/14

Pin Configurations and Typical Operating Circuits appear

at end of data sheet.

Functional Diagram

QSPI is a trademark of Motorola, Inc.

MICROWIRE is a registered trademark of National

Semiconductor Corp.

Ordering Information

Summary of content (39 pages)

PAGE 1
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan General Description The MAX6954 is a compact display driver that interfaces microprocessors to a mix of 7-segment, 14-segment, and 16-segment LED displays through an SPI-/ QSPI™-compatible 4-wire serial interface. The serial interface may be cascaded through multiple devices.
PAGE 2
MAX6954 4-Wire 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 All Other Pins...........................................-0.3V to (V+ + 0.3V) Current O0–O7 Sink Current......................................................935mA O0–O18 Source Current.................................................
PAGE 3
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan DC Electrical Characteristics (continued) (Typical Operating Circuits, V+ = 2.7V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 1) PARAMETER Segment Drive Source Current Segment Current Slew Rate Segment Drive Current Matching SYMBOL ISEG CONDITIONS VLED = 2.2V, V+ = 3.3V TA = +25°C MIN TYP MAX UNITS -34.5 -40 -46.5 mA DISEG/Dt TA = +25°C, V+ = 3.3V 11 DISEG TA = +25°C, V+ = 3.
PAGE 4
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Timing Characteristics (Typical Operating Circuits, V+ = 2.7V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS CLK Clock Period tCP 38.4 ns CLK Pulse Width High tCH 16 ns CLK Pulse Width Low tCL 16 ns CS Fall to CLK Rise Setup Time tCSS 9.5 ns CLK Rise to CS Rise Hold Time tCSH 0 ns DIN Setup Time tDS 9.
PAGE 5
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Typical Operating Characteristics (continued) (V+ = 3.3V, LED forward voltage = 2.4V, typical application circuit, TA = +25°C, unless otherwise noted.) 100 95 90 85 2.5 3.0 3.5 4.0 4.5 5.0 MAX6954 toc05 1.00 0.98 0.96 0.94 0.92 5.5 VLED = 1.8V 2.5 3.0 3.5 4.0 WAVEFORM AT PINS O0 AND O18, MAXIMUM INTENSITY MAX6954 toc06 5.5 5.0 GPIO SINK CURRENT vs. TEMPERATURE 45 OUTPUT = LOW VPORT = 0.
PAGE 6
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Pin Description PIN SSOP 1, 2, 34, 35, 36 PDIP TQFN-EP 1, 2, 36, 37, 38, 39, 40 33, 34, 35 NAME FUNCTION P0–P4 General-Purpose I/O Ports (GPIOs). GPIO can be configured as logic inputs or open-drain outputs. Enabling key scanning configures some or all ports P0–P3 as key-switch matrix inputs with internal pullup and port P4 as IRQ output. Chip-Select Input.
PAGE 7
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan 1a 1b 1f 2f 2b 1g 1e a 2a f 2g 2e 1c i j g1 e 2c 1dp h a1 m l k h i g1 g2 c 2dp e m j b g2 l k c dp 2d 1d f b a2 dp d2 d d1 Figure 1. Segment Labeling for 7-Segment Display, 14-Segment Display, and 16-Segment Display Table 1.
PAGE 8
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 2.
PAGE 9
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan DOUT MICROCONTROLLER CLK CS DIN DOUT CLK DOUT DIN MAX6954 CLK CS DIN MAX6954 CLK CS MAX6954 DOUT CS DIN Figure 2. MAX6954 Daisy-Chain Connection tCSW CS tCL tCSS CLK tDS DIN tCH tCSH tCP tDH D15 D14 D1 D0 tDO DOUT D15 Figure 3. Timing Diagram to read. Bits D7 to D0 contain dummy data, which is discarded.
PAGE 10
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan CS CLK DIN D15 D14 D13 D11 D12 D10 D8 D9 D7 D6 D5 D4 D3 D2 D1 D0 D15 = 0 DOUT Figure 4. Transmission of 16 Bits to the MAX6954 CS CLK DIN N-15 BIT 1 N-14 N-13 N-12 N-11 N-10 N-9 N-8 N-7 N-6 N-5 N-4 N-3 N-2 N-1 N N-25 N-24 N-23 N-22 N-21 N-20 N-19 N-18 N-17 N-16 BIT 2 DOUT N-31 N-30 N-29 N-28 N-27 N-26 N-15 Figure 5.
PAGE 11
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan A logic-high selects hexadecimal decoding, while a logic-low bypasses the decoder. When direct control is selected, the data bits D7 to D0 correspond to the segment lines of the MAX6954. Write x0010000 to blank all segments in hexadecimal decode mode. Display Blink Mode The display blinking facility, when enabled, makes the driver flip automatically between displaying the digit register data in planes P0 and P1.
PAGE 12
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Scan-Limit Register The scan-limit register sets how many 14-segment digits or 16-segment digits or pairs of 7-segment digits are displayed, from 1 to 8. A bicolor digit is connected as two monocolor digits. The scan register also limits the number of keys that can be scanned.
PAGE 13
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 6.
PAGE 14
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 6.
PAGE 15
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 6.
PAGE 16
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan START OF NEXT CYCLE ONE COMPLETE 1.
PAGE 17
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan LED OUTPUT O0 SW A0 SW B0 SW C0 SW D0 SW A1 SW B1 SW C1 SW D1 SW A2 SW B2 SW C2 SW D2 SW A3 SW B3 SW C3 SW D3 SW A4 SW B4 SW C4 SW D4 SW A5 SW B5 SW C5 SW D5 SW A6 SW B6 SW C6 SW D6 SW A7 SW B7 SW C7 SW D7 LED OUTPUT O1 LED OUTPUT O2 LED OUTPUT O3 LED OUTPUT O4 LED OUTPUT O5 LED OUTPUT O6 LED OUTPUT O7 VCC P0 P1 P2 P3 MICROCONTROLLER INTERRUPT P4 Figure 7.
PAGE 18
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan The bit is cleared if the switch has not been detected as pressed by the key-scanning circuit during the last test. Reading a pressed register does not clear that register or clear the IRQ output. Display Test Register The display test register (Table 36) operates in two modes: normal and display test.
PAGE 19
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan peak current ISEG, plus the 0.8V headroom required by the driver output stages. The MAX6954 correctly regulates ISEG with a supply voltage above this minimum voltage. If the supply drops below this minimum voltage, the driver output stages may brown out, and be unable to regulate the current correctly.
PAGE 20
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 7. 16-Segment Display Font Map LSB MSB x000 x001 x010 x011 x100 x101 x110 x111 Table 8. 14-Segment Display Font Map LSB MSB 0000 0000 0001 0001 0010 0010 0011 0011 0100 0100 0101 0101 0110 0110 0111 0111 1000 1000 1001 1001 1010 1010 1011 1011 1100 1100 1101 1101 1110 1110 1111 1111 x000 x001 x010 x011 x100 x101 x110 x111 . www.maximintegrated.
PAGE 21
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 9.
PAGE 22
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 11.
PAGE 23
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 13. Example Configurations for Display Digit Combinations DIGIT-TYPE REGISTER SETTING REGISTER DATA ADDRESS CODE (HEX) D7 D6 D5 D4 D3 D2 D1 D0 Digits 7 to 0 are 16-segment or 7-segment digits. 0x0C 0 0 0 0 0 0 0 0 Digit 0 is a 14-segment digit, digits 7 to 1 are 16-segment or 7-segment digits.
PAGE 24
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 15.
PAGE 25
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 16. Configuration Register Format MODE Configuration Register Table 17. Shutdown Control (S Data Bit DO) Format REGISTER DATA D7 D6 D5 D4 D3 D2 D1 D0 P I R T E B X S REGISTER DATA MODE D7 D6 D5 D4 D3 D2 D1 D0 Shutdown P I R T E B X 0 Normal Operation P I R T E B X 1 Table 18.
PAGE 26
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 23. Global Intensity (I Data Bit D6) Format REGISTER DATA MODE D7 D6 D5 D4 D3 D2 D1 D0 Intensity for all digits is controlled by one setting in the global intensity register. P 0 R T E B X S Intensity for digits is controlled by the individual settings in the intensity10 and intensity76 registers. P 1 R T E B X S Table 24.
PAGE 27
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 27.
PAGE 28
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 29. Odd Individual Segment Intensity Format DUTY CYCLE TYPICAL SEGMENT CURRENT (mA) ADDRESS CODE (HEX) D7 D6 D5 D4 1/16 (min on) 2.5 0x10 to 0x17 0 0 0 0 0x0X 2/16 5 0x10 to 0x17 0 0 0 1 0x1X 3/16 7.5 0x10 to 0x17 0 0 1 0 0x2X 4/16 10 0x10 to 0x17 0 0 1 1 0x3X 5/16 12.5 0x10 to 0x17 0 1 0 0 0x4X 6/16 15 0x10 to 0x17 0 1 0 1 0x5X 7/16 17.
PAGE 29
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 32.
PAGE 30
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Table 34.
PAGE 31
MAX6954 4-Wire Interfaced, 2.7V to 5.
PAGE 32
MAX6954 4-Wire Interfaced, 2.7V to 5.
PAGE 33
MAX6954 4-Wire Interfaced, 2.7V to 5.
PAGE 34
MAX6954 4-Wire Interfaced, 2.7V to 5.
PAGE 35
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Typical Operating Circuits 3.
PAGE 36
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Typical Operating Circuits (continued) 3.
PAGE 37
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Pin Configurations O2 9 32 O15 O3 10 27 O14 O3 10 O4 11 26 O13 O4 11 30 O13 O5 12 25 O12 O5 12 29 O12 O6 13 24 O11 O6 13 28 O11 O7 14 23 O10 O7 14 27 O10 MAX6954APL 31 O14 O8 15 22 O9 O8 15 26 O9 GND 16 21 V+ N.C. 16 25 N.C.
PAGE 38
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. LAND PATTERN NO.
PAGE 39
MAX6954 4-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan Revision History REVISION NUMBER REVISION DATE 3 6/08 Added TQFN package option 4 3/09 Corrected errors in Tables 37–40 5 7/14 Removed automotive reference from data sheet DESCRIPTION PAGES CHANGED 1, 2, 6, 37 31–34 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.