Rainbow Electronics MAX6959 User Manual

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 0; 10/02

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.

*EP = Exposed pad.

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.

PART

TEMP

RANGE

MAX6958AAEE -40°C to +125°C 0111000 16 QS O P - E P *

MAX6958AAPE -40°C to +125°C 0111000 16 DIP

SLAVE

ADDRESS

PIN­PACKAGE

8 88 8

µC

SDA

SCL

SDA

SCL

IRQ

IRQ/SEG9

MAX6959

INPUT1

INPUT2

DIG0–DIG3

SEG0–SEG8

Key0

Key1

Key2

Key3

Key4

Key5

Key6

Key7

8

5V

V+

GND

DIG0/SEG0

DIG1/SEG1

DIG2/SEG2

DIG3/SEG3

DIG4/SEG4

DIG5/SEG5

DIG6/SEG6

DIG7/SEG7

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 DIP (derate at 10.5mW/°C above +70°C).........842mW

16-Pin QSOP (derate at 8.34mW/°C above +70°C).....667mW

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 SYMBOL CONDITIONS MIN TYP MAX UNITS

Operating Supply Voltage V+ 3 5.5 V

Shutdown Supply Current I

Operating Supply Current I+

Display Scan Rate f

Keyscan Debounce Time t

Segment Drive Source Current I

Segment Current Slew Rate ∆I

Segment Drive Current Matching ∆I

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

SHDN

Shutdown mode, all
digital inputs at V+

Intensity set to full,
no display load
connected, INPUT1
and INPUT2 open
circuit

SCAN

DEBOUNCE

4 digits scanned TA = T

V

= 2.4V,

LED

V+ = 4.5V to 5.5V

SEG

V

LED

= 2V,

V+ = 3V to 5.5V

/∆t 11 mA/µs

SEG

SEG

, I

I

IH

IL

V

IH

V

IL

I

, I

INH

V

INH

V

INL

INPUT_ = V+ -1 +1 µA

INL

TA = +25°C2050

= T

T

A

to +85°C 125

MIN

TA = +25°C 5.9 6.7

T

= T

A

TA = T

MIN

MIN

MIN

to T

to T

to T

MAX

MAX

MAX

510 780 1050 Hz

30.3 41 63 ms

7.5

TA = +25°C -19 -23 -29

T

= T

MIN

to T

MAX

A

-18 -30

TA = +25°C -16 -29.5

T

= T

MIN

to T

MAX

A

-15.5 -30.5

4%

-1 +1 µA

2.1 V

0.8 V

0.7 ✕
V+

0.3 ✕
V+

µA

mA

mA

V

V

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)

)

TIMING CHARACTERISTICS

(V+ = 3V to 5.5V, TA= T

MIN

to T

MAX

, Figure 1, unless otherwise noted.) (Note 1)

Pullup to V+ INPUT1, INPUT2 I

IRQ/SEG9, SDA Output Low
Voltage

SDA Output Low Voltage V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

PULLUP

I

= 6mA, TA = -40°C to +85°C 0.4

V

OLBK

OL(SDA

SINK

I

= 4mA, TA = T

SINK

I

= 6mA 0.4 V

SINK

MIN

to T

Serial Clock Frequency f

Bus Free Time Between a STOP
and a START Condition

Hold Time (Repeated) START
Condition

Repeated START Setup Time t

STOP Condition Setup Time t

Data Hold Time t

Data Setup Time t

SCL Clock Low Period t

SCL Clock High Period t

Rise Time of Both SDA and SCL
Signals, Receiving

Fall Time of Both SDA and SCL
Signals, Receiving

Fall Time of SDA Transmitting t

Pulse Width of Spike Suppressed t

Capacitive Load for Each Bus
Line

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SCL

t

BUF

t

HD, STA

SU, STA

SU, STO

HD, DAT

SU, DAT

LOW

HIGH

t

t

SP

C

(Note 3) 0.9 µs

(Notes 2, 4)

R

(Notes 2, 4)

F

(Notes 2, 5)

F

(Note 6) 50 ns

B

MAX

26.5 µA

0.4

400 kHz

1.3 µs

0.6 µs

0.6 µs

0.6 µs

100 ns

1.3 µs

0.6 µs

20 +

0.1C

20 +

0.1C

20 +

0.1C

400 pF

B

B

B

300 ns

300 ns

250 ns

V

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

Table 1. Standard Driver Connection to LED Displays

PIN

MAX6958 MAX6959

1 1 SDA Serial Data I/O

2 2 SCL Serial Clock Input

3 — SEG9 Segment Output. Segment driver sourcing current to a display anode.

— 3 IRQ/SEG9

4–7, 11–15 4–7, 11–15 DIGX, SEGX

8 8 GND Ground

9, 10 — N.C. No Connect. Connect to V+ or leave open.

— 9 INPUT1

— 10 INPUT2

16 16 V+ Positive Supply Voltage

NAME FUNCTION

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.

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.

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.

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 _______________________________________________________________________________________

Figure 1. 2-Wire Serial Interface Timing Details

Figure 2. Start and Stop Conditions

SDA

t

SU, DAT

t

t

LOW

LOW

SCL

t

HD, STA

START

CONDITION

t

HIGH

t

R

t

HD, DAT

t

F

t

SU, STA

t

BUF

REPEATED START

CONDITION

t

HD, STA

t

SU, STO

STOP

CONDITION

START

CONDITION

SDA

SCL

S

START

CONDITION

P

STOP

CONDITION