19-2227; Rev 2; 3/05
KIT
ATION
EVALU
BLE
AVAILA
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
General Description
Features
♦
High-speed 26MHz SPI-, QSPI-, MICROWIRE-
Compatible Serial Interface
♦
+2.7V to +5.5V Operation
♦
Individual LED Segment Control
♦
Segment Blinking Control that Can Be
Synchronized Across Multiple Drivers
♦
Hexadecimal Decode/No-Decode Digit Selection
♦
Digital Brightness Control
♦
Display Blanked on Power-Up
♦
Drives Common-Cathode LED Digits
♦
Multiplex Clock Syncronizable to External Clock
♦
Slew-Rate Limited Segment Drivers for Low EMI
♦
75µA Low-Power Shutdown (Data Retained)
♦
Small 16-Pin QSOP Package
MAX6950/MAX6951
The MAX6950/MAX6951 are compact common-cathode
display drivers that interface microprocessors to individ-
ual 7-segment numeric LED digits, bar graph, or discrete
LEDs through an SPI™-, QSPI™-, MICROWIRE™-com-
patible serial interface. The supply voltage can be as low
as 2.7V.
The MAX6950 drives up to five 7-segment digits or 40
discrete LEDs. The MAX6951 drives up to eight 7-seg-
ment digits or 64 discrete LEDs.
Included on-chip are hexadecimal character decoders
(0–9, A–F), multiplex scan circuitry, segment and digit
drivers, and a static RAM that stores each digit. The
user may select hexadecimal decoding or no-decode
for each digit to allow any mix of 7-segment digits, bar
graph, or discrete LEDs to be driven. The segment cur-
rent for the LEDs is set by an internal digital brightness
control. The segment drivers are slew-rate limited to
reduce EMI.
Individual digits may be addressed and updated with-
out rewriting the entire display. The devices include a
low-power shutdown mode, digital brightness control, a
scan-limit register that allows the user to display from
one to eight digits, segment blinking that can be syn-
chronized across drivers, and a test mode that forces
all LEDs on.
Ordering Information
PART
MAX6950CEE
MAX6950EEE
MAX6951CEE
MAX6951EEE
TEMP RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP-EP*
16 QSOP-EP*
16 QSOP-EP*
16 QSOP-EP*
Applications
Set-Top Boxes
Panel Meters
White Goods
Bar Graphs and Matrix Displays
Industrial Controllers and Instrumentation
Professional Audio Equipment
Medical Equipment
*EP
= Exposed pad.
Pin Configuration
TOP VIEW
DIN 1
CLK 2
16 V+
15 CS
14 DIG4/SEG4
Functional Diagram appears at end of data sheet.
Typical Application appears at end of data sheet.
DIG3/SEG3 3
DIG2/SEG2 4
DIG1/SEG1 5
MAX6950
MAX6951
13 (DIG5)/SEG5
12 (DIG6)/SEG6
11 (DIG7)/SEG7
10 SEG8
9
OSC
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
DIG0/SEG0 6
ISET 7
GND 8
( ) MAX6951 ONLY
QSOP
________________________________________________________________
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.
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
MAX6950/MAX6951
ABSOLUTE MAXIMUM RATINGS
Voltage (with Respect to GND)
V+………………………………. ...................................-0.3V to 6V
All Other Pins................................................-0.3V to (V+ + 0.3V)
DIG1–DIG8 Sink Current.................................................. 440mA
SEG1–SEG9 Source Current.............................................. 55mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.34mW/°C above +70°C)........667mW
Operating Temperature Ranges (T
MIN
to T
MAX
)
MAX695_CEE....................................................0°C to +70°C
MAX695_EEE .................................................-40°C to +85°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.
ELECTRICAL CHARACTERISTICS
(Typical operating circuit, V+ = +3.0V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 1)
PARAMETER
Operating Supply Voltage
Shutdown Supply Current
SYMBOL
V+
I
SHDN
Shutdown mode, all digital
inputs at V+ or GND
Overtemperature
T
A
= +25 C
o
CONDITIONS
MIN
2.7
TYP
75
62
10
MAX
5.5
160
15
8
UNITS
V
µA
Operating Supply Current
I+
All segments on, all digits scanned,
intensity set to full, internal oscillator,
no display load connected
OSC = RC oscillator
1
mA
Master Clock Frequency (OSC
Internal Oscillator)
Master Clock Frequency (OSC
External Clock)
Display Scan Rate (OSC
External Clock)
Display Scan Rate (OSC Internal
Oscillator)
Display Scan Rate (OSC Internal
Oscillator)
OSC Internal/External Detection
Threshold
Dead Clock Protection
Frequency
OSC High Time (OSC External
Clock)
OSC Low Time (OSC External
Clock)
f
OSC
OSC = RC oscillator, R
SET
= 56kΩ,
C
SET
= 27pF
OSC overdriven externally
Eight digits scanned, OSC = overdriven
externally
Eight digits scanned, OSC = RC oscillator
Eight digits scanned, OSC = RC oscillator,
R
SET
= 56kΩ, C
SET
= 27pF
1
155
155
4
8
1250
1250
625
1.7
75.5
50
50
MHz
f
OSC
f
SCAN
f
SCAN
f
SCAN
V
OSC
f
OSC
t
CH
t
CL
MHz
Hz
Hz
Hz
V
kHz
ns
ns
2
_______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
ELECTRICAL CHARACTERISTICS
(Typical operating circuit, V+ = +3.0V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 1)
PARAMETER
Slow Segment Blink Period
(Internal Oscillator)
Fast Segment Blink Period
(Internal Oscillator)
Fast or Slow Segment Blink Duty
Cycle (Note 2)
Digit Drive Sink Current
Segment Drive Source Current
Digit Drive Sink Current (Note 2)
Segment Drive Source Current
(Note 2)
Slew Rate Rise Time
LOGIC INPUTS
Input Current DIN, CLK,
CS
Logic High Input Voltage DIN,
CLK,
CS
Logic Low Input Voltage DIN,
CLK,
CS
Hysteresis Voltage DIN, CLK,
CS
CLK Clock Period
CLK Pulse Width High
CLK Pulse Width Low
CS
Fall to CLK Rise Setup Time
CLK Rise to
CS
Rise Hold Time
DIN Setup Time
DIN Hold Time
CS
Pulse High
CLK Clock Period
CLK Pulse Width High
CLK Pulse Width Low
CS
Fall to CLK Rise Setup Time
CLK Rise to
CS
Rise Hold Time
DIN Setup Time
DIN Hold Time
CS
Pulse High
I
IH
, I
IL
V
IH
V
IL
∆V
I
t
CP
t
CH
t
CL
t
CSS
t
CSH
t
DS
t
DH
t
CSW
t
CP
t
CH
t
CL
t
CSS
t
CSH
t
DS
t
DH
t
CSW
38.4
19
19
9.5
3
9.5
0
19
50
24
24
12
4
12
4
24
0.5
V
IN
= 0 or V+
-2
2.4
0.4
2
µA
V
V
V
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
I
DIGIT
I
SEG
I
DIGIT
I
SEG
∆I
SEG
/∆t
T
A
= +25°C, V
LED
= 2.4V
T
A
= +25°C, V
LED
= 2.4V
T
A
= +25°C, V+ = 2.7V to 3V, V
LED
= 2.2V
T
A
= +25°C, V+ = 2.7V to 3V, V
LED
= 2.2V
T
A
= +25°C
SYMBOL
f
SLOWBLINK
f
FASTBLINK
CONDITIONS
Eight digits scanned, OSC = RC oscillator,
R
SET
= 56kΩ, C
SET
= 27pF
Eight digits scanned, OSC = RC oscillator,
R
SET
= 56kΩ, C
SET
= 27pF
49.9
240
-30
80
-10
35
MIN
TYP
1
0.5
50
320
-40
50.1
400
-50
MAX
UNITS
s
s
%
mA
mA
mA
mA
mA/µs
MAX6950/MAX6951
TIMING CHARACTERISTICS
(Figure 1)
TIMING CHARACTERISTICS (V+ = +2.7V)
(Note 2)
Note 1:
All parameters tested at T
A
= +25°C. Specifications over temperature are guaranteed by design.
Note 2:
Guaranteed by design.
_______________________________________________________________________________________
3
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
MAX6950/MAX6951
Typical Operating Characteristics
(Typical operating circuit, scan limit set to eight digits, V+ = +3.3V, V
LED
= 2.4V, T
A
= +25°C, unless otherwise noted.)
INTERNAL OSCILLATOR FREQUENCY
vs. TEMPERATURE
MAX6950/1 toc01
INTERNAL OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
4.30
4.20
4.10
4.00
3.90
3.80
3.70
MAX6950/1 toc02
4.40
4.30
OSCILLATOR FREQUENCY (MHz)
4.20
4.10
V+ = 3.3V
4.00
3.90
3.80
3.70
3.60
-40
-20
40
TEMPERATURE (°C)
0
20
60
80
V+ = 5V
V+ = 2.7V
4.40
OSCILLATOR FREQUENCY (MHz)
3.60
2
3
4
SUPPLY VOLTAGE (V)
5
6
INTERNAL OSCILLATOR WAVEFORM
AT OSC (PIN 9)
MAX6950/1 toc03
DEAD CLOCK OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
79
OSCILLATOR FREQUENCY (kHz)
78
77
76
75
74
73
72
71
MAX6950/1 toc04
80
3.0
2.5
2.0
1.5
1.0
0.5
0
0
200
400
600
800
TIMELINE (ns)
VOLTAGE AT OSC (V)
70
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
SUPPLY VOLTAGE (V)
SEGMENT SOURCE CURRENT
vs. SUPPLY VOLTAGE
MAX6950/1 toc05
WAVEFORM AT SEGO/DIGO (PIN 6)
V+ = 3.3V, 8 DIGITS SCANNED, 8/16 INTENSITY
MAX6950/1 toc06
1.01
CURRENT NORMALIZED TO 40mA
1.00
0.99
0.98
0.97
0.96
0.95
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
3.5
3.0
2.5
VOLTAGE (V)
2.0
1.5
DIGIT 0 MULTIPLEX TIMESLOT
1.0
0.5
0
6.0
0
500
SUPPLY VOLTAGE (V)
1000
TIMELINE (ns)
1500
2000
4
_______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
Pin Description
PIN
1
2
NAME
DIN
CLK
FUNCTION
Serial Data Input. Data is loaded into the internal 16–bit Shift register on CLK’s rising edge.
Serial-Clock Input. On CLK’s rising edge, data is shifted into the Internal Shift register. On CLK’s
falling edge, data is clocked out of DOUT. CLK input is active only while
CS
is low.
Digit X outputs sink current from the display common cathode when acting as digit drivers.
Segment X drivers source current to the display. Segment/digit drivers are high impedance when
turned off.
Current Setting. Connect to GND through a resistor (R
SET
) to set the peak current. This resistor,
together with capacitor C
SET
, also sets the multiplex clock frequency.
Ground
Multiplexer Clock Input. A capacitor (C
SET
) is connected to GND when the internal RC oscillator
multiplex clock is used. Resistor R
SET
(also used to set the peak current) and capacitor C
SET
together set the multiplex clock frequency. When the external clock is used, OSC should be driven
by a 1MHz to 8MHz clock.
Chip-Select Input. Serial data is loaded into the Shift register while
CS
is low. The last 16 bits of
serial data are latched on
CS’s
rising edge.
Positive Supply Voltage. Bypass to GND with a 0.1µF capacitor.
Exposed pad on package underside. Connect to GND.
MAX6950/MAX6951
3–6, 10–14
DIGX, SEGX
7
8
I
SET
GND
9
OSC
15
16
PAD
CS
V+
Exposed pad
Detailed Description
Differences Between
MAX6950 and MAX6951
The MAX6950 is a five-digit common-cathode display
driver. It drives five digits, with each digit comprising
eight LEDs with cathodes connected to a common
cathode. The display limit is therefore 40 LEDs or digit
segments.
The MAX6951 is an eight-digit common-cathode dis-
play driver. It drives eight digits, with each digit com-
prising eight LEDs. The only difference between the
MAX6950 and MAX6951 is that the MAX6950 is missing
three digit drivers. The MAX6950 can be configured to
scan eight digits, but if the last three digits are wired
up, they do not light.
The MAX6950/MAX6951 use a unique multiplexing
scheme to minimize the connections between the driver
and LED display. The scheme requires that the seg-
ment connections are different to each of the five
(MAX6950) or eight (MAX6951) digits (Table 1). This is
shown in the
Typical Application Circuit,
which uses
single-digit type displays. The MAX6950/MAX6951 are
not intended to drive multidigit display types, which
have the segments internally wired together, unless the
segments are wired with the common cathodes to fol-
low Table 1. The MAX6950/MAX6951 can drive multi-
digit LED displays that have the segments individually
pinned for each digit because then the digits can be
connected together correctly externally, just as if indi-
vidual digits were used.
Serial-Addressing Modes
The microprocessor interface on the MAX6950/
MAX6951 is a SPI-compatible 3-wire serial interface
using three input pins (Figure 1). This interface is used
to write configuration and display data to the MAX6950/
MAX6951. The serial interface data word length is 16
bits, which are labeled D15–D0 (Table 2). D15–D8 con-
tain the command address, and D7–D0 contain the
data. The first bit received is D15, the most-significant
bit (MSB). The three input pins are:
•
•
CLK is the serial clock input, and may idle low or
high at the start and end of a write sequence.
CS
is the MAX6950/MAX6951s’ chip-select input,
and must be low to clock data into the MAX6950/
MAX6951.
DIN is the serial data input, and must be stable
when it is sampled on the rising edge of the clock.
•
_______________________________________________________________________________________
5
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