19-2634; Rev 1; 11/05
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
General Description
The MAX6958/MAX6959 compact multiplexed com-
mon-cathode display drivers interface microprocessors
to seven-segment numeric LED digits, or discrete LEDs
through an SMBus™- and I
2
C-compatible 2-wire serial
interface. The 2-wire serial interface uses fixed
0.8V/2.1V logic thresholds for compatibility with 2.5V
and 3.3V systems when the display driver is powered
from a 5V supply.
The MAX6958/MAX6959 drive up to four 7-segment
digits, with decimal points, plus four discrete LEDs, or
four 7-segment digits and eight discrete LEDs if the
digits’ decimal points are not used, or up to 36 discrete
LEDs. The MAX6959 also includes two input ports, one
or both of which may be configured as a key-switch
reader, which automatically scans and debounces a
matrix of up to eight switches. Key-switch status is
obtained by polling internal status registers or by con-
figuring the MAX6959 interrupt output.
Other on-chip features include a hexadecimal font for
seven-segment displays, multiplex scan circuitry,
anode and cathode drivers, and static RAM that stores
each digit. The peak segment current for the display
digits is set internally to 23mA. Display intensity is
adjusted using a 64-step internal digital brightness con-
trol. The MAX6958/MAX6959 include a low-power shut-
down mode, a scan-limit register that allows the user to
display from one to four digits, and a test mode, which
forces all LEDs on. The LED drivers are slew-rate-limit-
ed to reduce EMI.
The MAX6958/MAX6959 are available in 16-pin PDIP
and QSOP packages and are fully specified over the
-40°C to +125°C automotive temperature range.
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
Features
400kbps 2-Wire Serial Interface
3V to 5.5V Operation
Drive 4 Digits plus 4 or 8 Discrete LEDs
Drive Common-Cathode LED Digits
23mA Constant-Current LED Segment Drive
Hexadecimal Decode/No-Decode Digit Selection
64-Step Digital Brightness Control
Slew-Rate-Limited Segment Drivers Reduced EMI
Debounces Up to Eight Switches with n-Key
Rollover (MAX6959 Only)
IRQ Output When a Key Input Is Debounced
(MAX6959 Only)
20µA Low-Power Shutdown (Data Retained)
Automotive Temperature Range (-40°C to +125°C)
Compact 16-Pin PDIP and QSOP Packages
MAX6958/MAX6959
Ordering Information
PART
MAX6958AAEE
MAX6958AAPE
TEMP
RANGE
-40°C to
+125°C
SLAVE
PIN-
ADDRESS PACKAGE
0111000
16 QSOP
PKG
CODE
E16-1
-40°C to
0111000 16 DIP
P16-1
+125°C
Ordering Information continued at end of data sheet.
Typical Operating Circuit
8
8
8
8
Applications
Set-Top Boxes
Panel Meters
White Goods
Audio/Video Equipment
Vending Machines
Industrial Controls
µC
SDA
SCL
IRQ
SDA
SCL
IRQ/SEG9
DIG0–DIG3
SEG0–SEG8
8
5V
V+
MAX6959
INPUT1
INPUT2
GND
Key0
DIG0/SEG0
Key1
DIG1/SEG1
Key2
DIG2/SEG2
Key3
DIG3/SEG3
Pin Configuration, Functional Diagram, and Typical
Application Circuit appear at end of data sheet.
Key4
DIG4/SEG4
Key5
DIG5/SEG5
Key6
DIG6/SEG6
Key7
DIG7/SEG7
SMBus is a trademark of Intel Corp.
________________________________________________________________
Maxim Integrated Products
1
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-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
MAX6958/MAX6959
ABSOLUTE MAXIMUM RATINGS
(Voltage with respect to GND.)
V+, SCL, SDA .......................................................-0.3V to +6V
All Other Pins............................................-0.3V to (V+ + 0.3V)
Current
DIG0/SEG0–DIG3/SEG3 Sink Current ..........................275mA
DIG0/SEG0–SEG9 Source Current .................................30mA
SCL, SDA, INPUT1, INPUT2 ...........................................20mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate at 8.34mW/°C above +70°C).....667mW
16-Pin DIP (derate at 10.5mW/°C above +70°C) .........842mW
Operating Temperature Range
MAX695_ (T
MIN
to T
MAX
) ...............................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(V+ = 3V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V+ = 5V, T
A
= +25°C.) (Note 1)
PARAMETER
Operating Supply Voltage
Shutdown Supply Current
SYMBOL
V+
I
SHDN
Shutdown mode, all
digital inputs at V+
Intensity set to full,
no display load
connected, INPUT1
and INPUT2 open
circuit
4 digits scanned
V
LED
= 2.4V,
V+ = 4.5V to 5.5V
Segment Drive Source Current
I
SEG
V
LED
= 2V,
V+ = 3V to 5.5V
T
A
= +25°C
T
A
= T
MIN
to +85°C
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= T
MIN
to T
MAX
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
510
30.3
-19
-18
-16
-15.5
11
4
780
41
-23
5.9
CONDITIONS
MIN
3
20
TYP
MAX
5.5
50
125
6.7
mA
UNITS
V
µA
Operating Supply Current
I+
7.5
Display Scan Rate
Keyscan Debounce Time
f
SCAN
t
DEBOUNCE
1050
63
-29
-30
-29.5
-30.5
Hz
ms
mA
Segment Current Slew Rate
Segment Drive Current Matching
LOGIC INPUTS AND OUTPUTS
Input Leakage Current SCL
and SDA
Logic High Input Voltage SCL,
SDA
Logic Low Input Voltage SCL,
SDA
Input Leakage Current INPUT1,
INPUT2
Logic High Input Voltage INPUT1,
INPUT2
Logic Low Input Voltage INPUT1,
INPUT2
∆I
SEG
/∆t
∆I
SEG
mA/µs
%
I
IH
, I
IL
V
IH
V
IL
I
INH
, I
INL
V
INH
V
INL
INPUT_ = V+
-1
2.1
+1
µA
V
0.8
-1
0.7
✕
V+
0.3
✕
V+
+1
V
µA
V
V
2
_______________________________________________________________________________________
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
DC ELECTRICAL CHARACTERISTICS (continued)
(V+ = 3V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V+ = 5V, T
A
= +25°C.) (Note 1)
PARAMETER
Pullup to V+ INPUT1, INPUT2
IRQ/SEG9, SDA Output Low
Voltage
SDA Output Low Voltage
SYMBOL
I
PULLUP
V
OLBK
V
OL(SDA)
I
SINK
= 6mA, T
A
= -40°C to +85°C
I
SINK
= 4mA, T
A
= T
MIN
to T
MAX
I
SINK
= 6mA
CONDITIONS
MIN
TYP
26.5
0.4
0.4
0.4
MAX
UNITS
µA
V
V
MAX6958/MAX6959
TIMING CHARACTERISTICS
(V+ = 3V to 5.5V, T
A
= T
MIN
to T
MAX
, Figure 1, unless otherwise noted.) (Note 1)
PARAMETER
Serial Clock Frequency
Bus Free Time Between a STOP
and a START Condition
Hold Time (Repeated) START
Condition
Repeated START Setup Time
STOP Condition Setup Time
Data Hold Time
Data Setup Time
SCL Clock Low Period
SCL Clock High Period
Rise Time of Both SDA and SCL
Signals, Receiving
Fall Time of Both SDA and SCL
Signals, Receiving
Fall Time of SDA Transmitting
Pulse Width of Spike Suppressed
Capacitive Load for Each Bus
Line
SYMBOL
f
SCL
t
BUF
t
HD, STA
t
SU, STA
t
SU, STO
t
HD, DAT
t
SU, DAT
t
LOW
t
HIGH
t
R
t
F
t
F
t
SP
C
B
(Notes 2, 4)
(Notes 2, 4)
(Notes 2, 5)
(Note 6)
(Note 3)
100
1.3
0.6
20 +
0.1C
B
20 +
0.1C
B
20 +
0.1C
B
50
400
300
300
250
1.3
0.6
0.6
0.6
0.9
CONDITIONS
MIN
TYP
MAX
400
UNITS
kHz
µs
µs
µs
µs
µs
ns
µs
µs
ns
ns
ns
ns
pF
Note 1:
All parameters tested at T
A
=+25°C. Specifications over temperature are guaranteed by design.
Note 2:
Guaranteed by design.
Note 3:
A master device must provide a hold time of at least 300ns for the SDA signal (referred to V
IL
of the SCL signal) in order to
bridge the undefined region of SCL’s falling edge.
Note 4:
C
B
= total capacitance of one bus line in pF. t
R
and t
F
measured between 0.3V+ and 0.7V+.
Note 5:
I
SINK
≤
6mA. C
B
= total capacitance of one bus line in pF. t
R
and t
F
measured between 0.3V+ and 0.7V+.
Note 6:
Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns.
_______________________________________________________________________________________
3
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
MAX6958/MAX6959
Typical Operating Characteristics
(V+ = 5V, LED forward voltage = 2.4V, T
A
= +25°C, unless otherwise noted.)
SCAN RATE (f
SCAN
)
vs. TEMPERATURE
MAX6958/59 toc01
KEYSCAN DEBOUNCE TIME (t
DEBOUNCE
)
vs. TEMPERATURE
MAX6958/59 toc02
SCAN RATE (f
SCAN
)
vs. SUPPLY VOLTAGE
MAX6958/59 toc03
800
795
790
SCAN RATE (Hz)
785
780
775
770
765
760
755
-40
-20
0
20
40
60
80
100 120
TEMPERATURE (°C)
3V
4.5V
5V
5.5V
42.5
3V
KEYSCAN DEBOUNCE TIME (ms)
42.0
4.5V
41.5
5V
5.5V
41.0
790
785
SCAN RATE (Hz)
780
775
770
765
760
40.5
40.0
-40
-20
0
20
40
60
80
100 120
TEMPERATURE (°C)
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
KEYSCAN DEBOUNCE TIME (t
DEBOUNCE
)
vs. SUPPLY VOLTAGE
MAX6958/59 toc04
SEGMENT SOURCE CURRENT
vs. SUPPLY VOLTAGE
MAX6958/59 toc05
SEGMENT SOURCE CURRENT
vs. SUPPLY VOLTAGE
MAX6958/59 toc06
42.2
42.0
KEYSCAN DEBOUNCE TIME (ms)
41.8
41.6
41.4
41.2
41.0
40.8
40.6
40.4
3.0
3.5
4.0
4.5
5.0
25
SEGMENT SOURCE CURRENT (mA)
25
SEGMENT SOURCE CURRENT (mA)
20
20
15
15
10
10
5
V
LED
= 2.4V
4.50
4.75
5.00
5.25
5.50
5
V
LED
= 2V
3.0
3.5
4.0
4.5
5.0
5.5
0
5.5
SUPPLY VOLTAGE (V)
0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
WAVEFORM AT DIG0/SEG0,
FULL INTENSITY
MAX6958/59 toc07
INPUT PULLUP CURRENT
vs. TEMPERATURE
40
INPUT PULLUP CURRENT (µA)
35
30
25
20
15
10
5
0
3V
5.5V
5V
4.5V
MAX6958/59 toc08
45
V
DIG0
/
SEG0
1V/div
200µs/div
-40
-20
0
20
40
60
80
100 120
TEMPERATURE (°C)
4
_______________________________________________________________________________________
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
Pin Description
PIN
MAX6958
1
2
3
—
MAX6959
1
2
—
3
NAME
SDA
SCL
SEG9
IRQ/SEG9
Serial Data I/O
Serial Clock Input
Segment Output. Segment driver sourcing current to a display anode.
Interrupt or Segment Output. May be segment driver sourcing current to a display
anode, or open-drain interrupt output, or open-drain logic output.
Digit and Segment Drivers. Digit X outputs sink current from the display common
cathode when acting as digit drivers. Segment X drivers source current to the display
anodes. Segment/digit drivers are high impedance when turned off.
Ground
No Connect. Connect to V+ or leave open.
General-Purpose Input Port 1 with Internal Pullup. May be configured as general-
purpose logic input or keyscan input. Connect to V+ or leave open if unused.
General-Purpose Input Port 2 with Internal Pullup. May be configured as general-
purpose logic input or keyscan input. Connect to V+ or leave open if unused.
Positive Supply Voltage
FUNCTION
MAX6958/MAX6959
4–7, 11–15
8
9, 10
—
—
16
4–7, 11–15
8
—
9
10
16
DIGX, SEGX
GND
N.C.
INPUT1
INPUT2
V+
Detailed Description
The MAX6958/MAX6959 serially interfaced display dri-
vers drive up to: four 7-segment digits plus four dis-
crete LEDs if the decimal points are used, or four
7-segment digits plus eight discrete LEDs if the deci-
mal points are not used, or 36 discrete LEDs. Table 1
lists the display connection scheme.
The MAX6958/MAX6959 include the hexadecimal font
map for seven-segment displays. The seven-segment
LED digits can be controlled directly or programmed to
use the hexadecimal font. Direct segment control
allows the MAX6958/MAX6959 to drive bar graphs and
discrete LED indicators.
The MAX6958/MAX6959 use a multiplexing scheme that
minimizes the connections between the driver and LED
display. The MAX6958/MAX6959 can drive monocolor
and bicolor single-digit type displays, and monocolor
dual-digit displays. Dual-digit displays internally
wire together the equivalent segments for each digit,
requiring only eight segment pins instead of 16. The
MAX6958/MAX6959 can also drive multidigit LED dis-
plays that have the segments individually pinned for
each digit.
To connect four single-digit displays to the MAX6958/
MAX6959, connect cathode outputs DIG0/SEG0–
DIG3/SEG3 to the cathodes of the four display digits as
shown in Table 1 (CC0–CC3). Drive eight additional
LEDs with SEG0 to SEG7. Four of the eight LEDs can
be the decimal point (DP) segments of the four dis-
plays, and the other four can be discrete LED indica-
tors.
To connect two dual-digit displays to the MAX6958/
MAX6959, connect cathode outputs DIG0/SEG0 and
DIG1/SEG1 to the cathodes of the first dual digit.
Connect DIG2/SEG2 and DIG3/SEG3 to the cathodes
of the second dual digit. SEG0 to SEG3 can only drive
discrete LEDs, not digit DP segments. SEG4 to SEG7
can drive the DP segments if required. Bicolor single-
digit displays are connected and treated as dual-digit
displays, each digit being one of the two colors.
Table 1. Standard Driver Connection to LED Displays
DIG0/SEG0 DIG1/SEG1
LED Digit 0
LED Digit 1
LED Digit 2
LED Digit 3
CC0
SEG 1
SEG g
SEG g
SEG 0
CC1
SEG f
SEG f
DIG2/SEG2
SEG g
SEG g
CC2
SEG 3
DIG3/SEG3
SEG f
SEG f
SEG 2
CC3
SEG 4
SEG e
SEG e
SEG e
SEG e
SEG 5
SEG d
SEG d
SEG d
SEG d
SEG 6
SEG c
SEG c
SEG c
SEG c
SEG 7
SEG b
SEG b
SEG b
SEG b
SEG 8
SEG a
SEG a
SEG a
SEG a
SEG 9/IRQ
SEG 4
SEG 5
SEG 6
SEG 7
_______________________________________________________________________________________
5
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