MAXIM IMAX6958, MAX6959 Technical data
General Description
The MAX6958/MAX6959 compact multiplexed common-cathode display drivers interface microprocessors
to seven-segment numeric LED digits, or discrete LEDs
through an SMBus™- and I2C-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 configuring 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 control. The MAX6958/MAX6959 include a low-power shutdown 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-limited 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.
Applications
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
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-2634; Rev 1; 11/05
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.
Ordering Information continued at end of data sheet.
PART
TEMP
SLAVE
PIN-
PKG
CODE
MAX6958AAEE
-40°C to
16 QS OP
E 16- 1
MAX6958AAPE
-40°C to
+125°C
16 DIP
P16-1
V+
DIG0–DIG3
SEG0–SEG8
SDA
SCL
IRQ/SEG9
INPUT1
µC
SDA
SCL
IRQ
8
INPUT2
GND
8 88 8
5V
Key0
DIG0/SEG0
Key1
DIG1/SEG1
Key2
DIG2/SEG2
Key3
DIG3/SEG3
Key4
DIG4/SEG4
Key5
DIG5/SEG5
Key6
DIG6/SEG6
Key7
DIG7/SEG7
MAX6959
Typical Operating Circuit
SMBus is a trademark of Intel Corp.
Set-Top Boxes
Panel Meters
White Goods
Audio/Video Equipment
Vending Machines
Industrial Controls
Pin Configuration, Functional Diagram, and Typical
Application Circuit appear at end of data sheet.
RANGE
+125°C
ADDRESS
0111000
0111000
PACKAGE
MAX6958/MAX6959
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(V+ = 3V to 5.5V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V+ = 5V, TA= +25°C.) (Note 1)
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.
(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 (TA= +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
PARAMETER
CONDITIONS
UNITS
Operating Supply Voltage V+ 3 5.5 V
TA = +25°C 20 50
Shutdown Supply Current I
SHDN
Shutdown mode, all
TA = T
MIN
to +85°C 125
µA
TA = +25°C 5.9 6.7
Operating Supply Current I+
Intensity set to full,
no display load
connected, INPUT1
and INPUT2 open
circuit
T
A
= T
MIN
to T
MAX
7.5
mA
Display Scan Rate f
SCAN
4 digits scanned TA = T
MIN
to T
MAX
Hz
Keyscan Debounce Time
TA = T
MIN
to T
MAX
41 63 ms
TA = +25°C -19 -23 -29
V
LED
= 2.4V,
V+ = 4.5V to 5.5V
T
A
= T
MIN
to T
MAX
-18 -30
TA = +25°C -16
Segment Drive Source Current I
SEG
V
LED
= 2V,
V+ = 3V to 5.5V
T
A
= T
MIN
to T
MAX
mA
Segment Current Slew Rate
11
mA/µs
Segment Drive Current Matching
∆I
SEG
4%
LOGIC INPUTS AND OUTPUTS
Input Leakage Current SCL
and SDA
I
IH
, I
IL
-1 +1 µA
Logic High Input Voltage SCL,
SDA
V
IH
2.1 V
Logic Low Input Voltage SCL,
SDA
V
IL
0.8 V
Input Leakage Current INPUT1,
INPUT2
INPUT_ = V+ -1 +1 µA
Logic High Input Voltage INPUT1,
INPUT2
V
INH
0.7 ✕
V+
V
Logic Low Input Voltage INPUT1,
INPUT2
V
INL
0.3 ✕
V+
V
SYMBOL
MIN TYP MAX
t
DEBOUNCE
digital inputs at V+
510 780 1050
30.3
∆I
/∆t
SEG
-15.5 -30.5
I
, I
INH
INL
-29.5
MAX6958/MAX6959
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
_______________________________________________________________________________________ 3
Note 1: All parameters tested at TA=+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. tRand tFmeasured between 0.3V+ and 0.7V+.
Note 5: I
SINK
≤ 6mA. CB= total capacitance of one bus line in pF. tRand tFmeasured between 0.3V+ and 0.7V+.
Note 6: Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns.
DC ELECTRICAL CHARACTERISTICS (continued)
(V+ = 3V to 5.5V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V+ = 5V, TA= +25°C.) (Note 1)
PARAMETER
CONDITIONS
UNITS
Pullup to V+ INPUT1, INPUT2
µA
I
SINK
= 6mA, TA = -40°C to +85°C 0.4
IRQ/SEG9, SDA Output Low
Voltage
V
OLBK
I
SINK
= 4mA, TA = T
MIN
to T
MAX
0.4
V
SDA Output Low Voltage
)
I
SINK
= 6mA 0.4 V
TIMING CHARACTERISTICS
(V+ = 3V to 5.5V, TA= T
MIN
to T
MAX
, Figure 1, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Serial Clock Frequency f
SCL
400 kHz
Bus Free Time Between a STOP
and a START Condition
t
BUF
1.3 µs
Hold Time (Repeated) START
Condition
0.6 µs
Repeated START Setup Time
0.6 µs
STOP Condition Setup Time
0.6 µs
Data Hold Time
(Note 3) 0.9 µs
Data Setup Time
100 ns
SCL Clock Low Period t
LOW
1.3 µs
SCL Clock High Period t
HIGH
0.6 µs
Rise Time of Both SDA and SCL
Signals, Receiving
t
R
(Notes 2, 4)
20 +
300 ns
Fall Time of Both SDA and SCL
Signals, Receiving
t
F
(Notes 2, 4)
20 +
300 ns
Fall Time of SDA Transmitting t
F
(Notes 2, 5)
20 +
250 ns
Pulse Width of Spike Suppressed
t
SP
(Note 6) 50 ns
Capacitive Load for Each Bus
Line
C
B
pF
SYMBOL
I
PULLUP
V
OL(SDA
t
HD, STA
t
SU, STA
t
SU, STO
t
HD, DAT
t
SU, DAT
MIN TYP MAX
26.5
0.1C
B
0.1C
B
0.1C
B
400
MAX6958/MAX6959
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
4 _______________________________________________________________________________________
Typical Operating Characteristics
(V+ = 5V, LED forward voltage = 2.4V, TA= +25°C, unless otherwise noted.)
SCAN RATE (f
SCAN
)
vs. TEMPERATURE
MAX6958/59 toc01
TEMPERATURE (°C)
SCAN RATE (Hz)
1008040 600 20-20
760
765
770
775
780
785
790
795
800
755
-40 120
5.5V
5V
3V
4.5V
KEYSCAN DEBOUNCE TIME (t
DEBOUNCE
)
vs. TEMPERATURE
MAX6958/59 toc02
TEMPERATURE (°C)
KEYSCAN DEBOUNCE TIME (ms)
100806040200-20
40.5
41.0
41.5
42.0
42.5
40.0
-40 120
4.5V
5V
3V
5.5V
SCAN RATE (f
SCAN
)
vs. SUPPLY VOLTAGE
MAX6958/59 toc03
SUPPLY VOLTAGE (V)
SCAN RATE (Hz)
5.04.54.03.5
765
770
775
780
785
790
760
3.0 5.5
KEYSCAN DEBOUNCE TIME (t
DEBOUNCE
)
vs. SUPPLY VOLTAGE
MAX6958/59 toc04
SUPPLY VOLTAGE (V)
KEYSCAN DEBOUNCE TIME (ms)
5.04.54.03.5
40.6
40.8
41.0
41.2
41.4
41.6
41.8
42.0
42.2
40.4
3.0 5.5
SEGMENT SOURCE CURRENT
vs. SUPPLY VOLTAGE
MAX6958/59 toc05
SUPPLY VOLTAGE (V)
SEGMENT SOURCE CURRENT (mA)
5.255.004.75
5
10
15
20
25
0
4.50 5.50
V
LED
= 2.4V
SEGMENT SOURCE CURRENT
vs. SUPPLY VOLTAGE
MAX6958/59 toc06
SUPPLY VOLTAGE (V)
SEGMENT SOURCE CURRENT (mA)
4.54.03.5
5
10
15
20
25
0
3.0 5.0 5.5
V
LED
= 2V
WAVEFORM AT DIG0/SEG0,
FULL INTENSITY
MAX6958/59 toc07
V
DIG0
/
SEG0
1V/div
200µs/div
INPUT PULLUP CURRENT
vs. TEMPERATURE
MAX6958/59 toc08
TEMPERATURE (°C)
INPUT PULLUP CURRENT (µA)
1008040 600 20-20
5
10
15
20
25
30
35
40
45
0
-40 120
5.5V
5V
3V
4.5V
Detailed Description
The MAX6958/MAX6959 serially interfaced display drivers drive up to: four 7-segment digits plus four discrete LEDs if the decimal points are used, or four
7-segment digits plus eight discrete LEDs if the decimal 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 displays 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 displays, and the other four can be discrete LED indicators.
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 singledigit displays are connected and treated as dual-digit
displays, each digit being one of the two colors.
MAX6958/MAX6959
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
_______________________________________________________________________________________ 5
Pin Description
PIN
MAX6958
NAME FUNCTION
11SDA Serial Data I/O
22SCL Serial Clock Input
3—SEG9 Segment Output. Segment driver sourcing current to a display anode.
—3IRQ/SEG9
Interrupt or Segment Output. May be segment driver sourcing current to a display
anode, or open-drain interrupt output, or open-drain logic output.
4–7, 11–15
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.
88GND Ground
9, 10 — N.C. No Connect. Connect to V+ or leave open.
—9INPUT1
General-Purpose Input Port 1 with Internal Pullup. May be configured as generalpurpose logic input or keyscan input. Connect to V+ or leave open if unused.
—10INPUT2
General-Purpose Input Port 2 with Internal Pullup. May be configured as generalpurpose logic input or keyscan input. Connect to V+ or leave open if unused.
16 16 V+ Positive Supply Voltage
Table 1. Standard Driver Connection to LED Displays
MAX6959
4–7, 11–15 DIGX, SEGX
LED Digit 0 CC0 SEG 0 SEG g SEG f SEG e SEG d SEG c SEG b SEG a SEG 4
LED Digit 1 SEG 1 CC1 SEG g SEG f SEG e SEG d SEG c SEG b SEG a SEG 5
LED Digit 2 SEG g SEG f CC2 SEG 2 SEG e SEG d SEG c SEG b SEG a SEG 6
LED Digit 3 SEG g SEG f SEG 3 CC3 SEG e SEG d SEG c SEG b SEG a SEG 7
DIG0/SEG0 DIG1/SEG1 DIG2/SEG2 DIG3/SEG3 SEG 4 SEG 5 SEG 6 SEG 7 SEG 8 SEG 9/IRQ
MAX6958/MAX6959
Differences Between MAX6958
and MAX6959
The MAX6958/MAX6959 have the same LED drive
capability, four common-cathode digits of nine segments per digit. The MAX6959 additionally contains two
logic input ports, INPUT1 and INPUT2. Each input port
can be individually configured as either a general-purpose input port that is read through the serial interface,
or as a keyscan input. In keyscan mode, the input is
used to read and automatically debounce four key
switches. A maximum of eight key switches can be
read if both INPUT1 and INPUT2 are assigned to
keyscanning.
The MAX6958's SEG9 output is preconfigured as the
9th LED segment output. The IRQ/SEG9 output on the
MAX6959 can be configured as either an open-drain
logic output or the 9th segment output. This logic output serves as either a general-purpose logic output, set
through the serial interface, or an interrupt (IRQ) output
that alerts a microcontroller of debounced key-switch
events. Key-switch status can also be obtained by
polling the internal status registers at any time.
Use the Option bit in the configuration register to detect
whether a MAX6958 or MAX6959 is present. The option
bit allows host software to establish whether a high-end
front panel (using the MAX6959 for keyscan support) or
a low-end panel (using a MAX6958 and no key switches) is fitted to a product.
Serial Interface
Serial Addressing
The MAX6958/MAX6959 operate as a slave that sends
and receives data through a 2-wire interface. The interface uses a serial data line (SDA) and a serial clock line
(SCL) to achieve bidirectional communication between
master(s) and slave(s). A master, typically a microcontroller, initiates all data transfers to and from the
MAX6958/MAX6959, and generates the SCL clock that
synchronizes the data transfer (Figure 1).
The MAX6958/MAX6959 SDA line operates as both an
input and an open-drain output. A pullup resistor, typically 4.7kΩ, is required on the SDA bus. The MAX6958/
MAX6959 SCL line operates only as an input. A pullup
resistor, typically 4.7kΩ, is required on the SCL bus if
there are multiple masters on the 2-wire interface, or if
the master in a single-master system has an open-drain
SCL output.
Each transmission consists of a START condition
(Figure 2) sent by a master, followed by the MAX6958/
MAX6959 7-bit slave address plus R/W bit (Figure 3), 1
or more data bytes, and finally a STOP condition
(Figure 2).
Start and Stop Conditions
Both SCL and SDA remain high when the interface is
not busy. A master signals the beginning of a transmission with a START (S) condition by transitioning SDA
from high to low while SCL is high. When the master
has finished communicating with the slave, it issues a
STOP (P) condition by transitioning the SDA from low to
high while SCL is high. The bus is then free for another
transmission (Figure 2).
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
9-Segment LED Display Drivers with Keyscan
6 _______________________________________________________________________________________
t
LOW
SDA
t
LOW
t
SU, DAT
t
HD, DAT
t
R
SCL
START
CONDITION
STOP
CONDITION
START
CONDITION
REPEATED START
CONDITION
t
F
t
HIGH
t
HD, STA
t
SU, STA
t
HD, STA
t
SU, STO
t
BUF
Figure 1. 2-Wire Serial Interface Timing Details
SDA
START
CONDITION
SCL
S
STOP
CONDITION
P
Figure 2. Start and Stop Conditions
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