19-2227; Rev 1; 12/01
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
Features
The MAX6950/MAX6951 are compact common-cathode display drivers that interface microprocessors to
individual 7-segment numeric LED digits, bar graph, or
discrete LEDs through an SPI™-, QSPI™-MICROWIRE™compatible 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-segment 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 current for the LEDs is set by an internal digital brightness
control. The segment drivers are slew-rate limited to
reduce EMI.
♦ High-speed 26MHz SPI-, QSPI-, MICROWIRECompatible Serial Interface
Individual digits may be addressed and updated without 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 synchronized across drivers, and a test mode that forces
all LEDs on.
♦ Small 16-Pin QSOP Package
Applications
Set-Top Boxes
Panel Meters
♦ +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)
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX6950CEE
0°C to +70°C
16 QSOP
MAX6950EEE
-40°C to +85°C
16 QSOP
MAX6951CEE
0°C to +70°C
16 QSOP
MAX6951EEE
-40°C to +85°C
16 QSOP
White Goods
Bar Graphs and Matrix Displays
Industrial Controllers and Instrumentation
Professional Audio Equipment
Pin Configuration
Medical Equipment
TOP VIEW
Functional Diagram appears at end of data sheet.
Typical Application appears at end of data sheet.
DIN 1
16 V+
CLK 2
15 CS
DIG3/SEG3 3
DIG2/SEG2 4
DIG1/SEG1 5
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
14 DIG4/SEG4
MAX6950
MAX6951
DIG0/SEG0 6
( ) MAX6951 ONLY
13 (DIG5)/SEG5
12 (DIG6)/SEG6
11 (DIG7)/SEG7
ISET 7
10 SEG8
GND 8
9
OSC
QSOP
________________________________________________________________ Maxim Integrated Products
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.
1
MAX6950/MAX6951
General Description
MAX6950/MAX6951
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
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 (TA = +70°C)
16-Pin QSOP (derate 8.34mW/°C above +70°C)........667mW
Operating Temperature Ranges (TMIN to TMAX)
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, TA = TMIN to TMAX, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
Operating Supply Voltage
V+
Shutdown Supply Current
ISHDN
Operating Supply Current
I+
CONDITIONS
TYP
2.7
Shutdown mode, all digital
inputs at V+ or GND
MAX
UNITS
5.5
V
Overtemperature
75
TA = +25oC
62
160
10
15
All segments on, all digits scanned,
intensity set to full, internal oscillator,
no display load connected
OSC = RC oscillator
2
MIN
Master Clock Frequency (OSC
Internal Oscillator)
fOSC
OSC = RC oscillator, RSET = 56kΩ,
CSET = 27pF
Master Clock Frequency (OSC
External Clock)
fOSC
OSC overdriven externally
Display Scan Rate (OSC
External Clock)
fSCAN
Display Scan Rate (OSC Internal
Oscillator)
1
µA
mA
8
MHz
4
1
8
MHz
Eight digits scanned, OSC = overdriven
externally
155
1250
Hz
fSCAN
Eight digits scanned, OSC = RC oscillator
155
1250
Hz
Display Scan Rate (OSC Internal
Oscillator)
fSCAN
Eight digits scanned, OSC = RC oscillator,
RSET = 56kΩ, CSET = 27pF
OSC Internal/External Detection
Threshold
Dead Clock Protection
Frequency
625
Hz
VOSC
1.7
V
fOSC
75.5
kHz
OSC High Time (OSC External
Clock)
tCH
50
ns
OSC Low Time (OSC External
Clock)
tCL
50
ns
_______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
(Typical operating circuit, V+ = +3.0V to +5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
Slow Segment Blink Period
(Internal Oscillator)
fSLOWBLINK
Eight digits scanned, OSC = RC oscillator,
RSET = 56kΩ, CSET = 27pF
1
s
Fast Segment Blink Period
(Internal Oscillator)
fFASTBLINK
Eight digits scanned, OSC = RC oscillator,
RSET = 56kΩ, CSET = 27pF
0.5
s
Fast or Slow Segment Blink Duty
Cycle (Note 2)
Digit Drive Sink Current
MIN
TYP
MAX
UNITS
49.9
50
50.1
%
IDIGIT
TA = +25°C, VLED = 2.4V
240
320
400
mA
Segment Drive Source Current
ISEG
TA = +25°C, VLED = 2.4V
-30
-40
-50
mA
Digit Drive Sink Current (Note 2)
IDIGIT
TA = +25°C, V+ = 2.7V to 3V, VLED = 2.2V
80
mA
Segment Drive Source Current
(Note 2)
ISEG
TA = +25°C, V+ = 2.7V to 3V, VLED = 2.2V
-10
mA
Slew Rate Rise Time
∆ISEG/∆t
TA = +25°C
35
mA/µs
LOGIC INPUTS
Input Current DIN, CLK, CS
IIH, IIL
Logic High Input Voltage DIN,
CLK, CS
VIH
Logic Low Input Voltage DIN,
CLK, CS
VIL
Hysteresis Voltage DIN, CLK, CS
∆VI
VIN = 0 or V+
-2
2
2.4
µA
V
0.4
0.5
V
V
TIMING CHARACTERISTICS (Figure 1)
CLK Clock Period
tCP
38.4
ns
CLK Pulse Width High
tCH
19
ns
ns
CLK Pulse Width Low
tCL
19
CS Fall to CLK Rise Setup Time
tCSS
9.5
ns
CLK Rise to CS Rise Hold Time
tCSH
3
ns
DIN Setup Time
tDS
9.5
ns
DIN Hold Time
tDH
0
ns
CS Pulse High
tCSW
19
ns
tCP
50
ns
tCH
24
ns
ns
TIMING CHARACTERISTICS (V+ = +2.7V) (Note 2)
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
tCL
24
tCSS
12
ns
ns
tCSH
4
DIN Setup Time
tDS
12
ns
DIN Hold Time
tDH
4
ns
CS Pulse High
tCSW
24
ns
Note 1: All parameters tested at TA = +25°C. Specifications over temperature are guaranteed by design.
Note 2: Guaranteed by design.
_______________________________________________________________________________________
3
MAX6950/MAX6951
ELECTRICAL CHARACTERISTICS
Typical Operating Characteristics
(Typical operating circuit, scan limit set to eight digits, V+ = +3.3V, VLED = 2.4V, TA = +25°C, unless otherwise noted.)
INTERNAL OSCILLATOR FREQUENCY
vs. TEMPERATURE
INTERNAL OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
V+ = 2.7V
4.20
4.10
V+ = 3.3V
4.00
V+ = 5V
3.90
3.80
3.70
MAX6950/1 toc02
OSCILLATOR FREQUENCY (MHz)
4.30
4.40
OSCILLATOR FREQUENCY (MHz)
MAX6950/1 toc01
4.40
4.30
4.20
4.10
4.00
3.90
3.80
3.70
3.60
-40
-20
0
20
60
40
TEMPERATURE (°C)
3.60
80
2
4
5
6
DEAD CLOCK OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
2.0
1.5
1.0
MAX6950/1 toc04
MAX6950/1 toc03
2.5
80
79
OSCILLATOR FREQUENCY (kHz)
0.5
78
77
76
75
74
73
72
71
70
0
0
200
400
600
2.0
800
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
TIMELINE (ns)
SUPPLY VOLTAGE (V)
SEGMENT SOURCE CURRENT
vs. SUPPLY VOLTAGE
WAVEFORM AT SEGO/DIGO (PIN 6)
V+ = 3.3V, 8 DIGITS SCANNED, 8/16 INTENSITY
3.5
MAX6950/1 toc05
1.01
1.00
MAX6950/1 toc06
VOLTAGE AT OSC (V)
3.0
3.0
2.5
VOLTAGE (V)
0.99
0.98
2.0
1.5
0.97
DIGIT 0 MULTIPLEX TIMESLOT
1.0
0.96
0.5
0.95
2.0
2.5
3.0
3.5
4.0
4.5
5.0
SUPPLY VOLTAGE (V)
4
3
SUPPLY VOLTAGE (V)
INTERNAL OSCILLATOR WAVEFORM
AT OSC (PIN 9)
CURRENT NORMALIZED TO 40mA
MAX6950/MAX6951
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
5.5
6.0
0
0
500
1000
TIMELINE (ns)
1500
2000
_______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
PIN
NAME
FUNCTION
1
DIN
Serial Data Input. Data is loaded into the internal 16–bit Shift register on CLK’s rising edge.
2
CLK
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.
3–6, 10–14
DIGX, SEGX
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.
7
ISET
Current Setting. Connect to GND through a resistor (RSET) to set the peak current. This resistor,
together with capacitor CSET, also sets the multiplex clock frequency.
8
GND
Ground
9
OSC
Multiplexer Clock Input. A capacitor (CSET) is connected to GND when the internal RC oscillator
multiplex clock is used. Resistor RSET (also used to set the peak current) and capacitor CSET
together set the multiplex clock frequency. When the external clock is used, OSC should be driven
by a 1MHz to 8MHz clock.
15
CS
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.
16
V+
Positive Supply Voltage. Bypass to GND with a 0.1µF capacitor.
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 display driver. It drives eight digits, with each digit comprising 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 segment 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 follow 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 individual 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 contain 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.
The serial interface comprises a 16-bit shift register into
which DIN data is clocked on the rising edge of CLK
when CS is low. When CS is high, transitions on CLK do
not clock data into the shift register. When CS goes
_______________________________________________________________________________________
5
MAX6950/MAX6951
Pin Description
MAX6950/MAX6951
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
Table 1. Standard Driver Connection to Single-Digit Displays
DIG/SEG0
PIN 6
DIG/SEG1
PIN 5
DIG/SEG2
PIN 4
DIG/SEG3
PIN 3
DIG/SEG4
PIN 14
DIG/SEG5
PIN 13
DIG/SEG6
PIN 12
DIG/SEG7
PIN 11
SEG 8
PIN 10
LED Digit 0
CC0
SEG dp
SEG g
SEG f
SEG e
SEG d
SEG c
SEG b
SEG a
LED Digit 1
SEG dp
CC1
SEG g
SEG f
SEG e
SEG d
SEG c
SEG b
SEG a
LED Digit 2
SEG dp
SEG g
CC2
SEG f
SEG e
SEG d
SEG c
SEG b
SEG a
LED Digit 3
SEG dp
SEG g
SEG f
CC3
SEG e
SEG d
SEG c
SEG b
SEG a
LED Digit 4
SEG dp
SEG g
SEG f
SEG e
CC4
SEG d
SEG c
SEG b
SEG a
LED Digit 5
SEG dp
SEG g
SEG f
SEG e
SEG d
CC5
SEG c
SEG b
SEG a
LED Digit 6
SEG dp
SEG g
SEG f
SEG e
SEG d
SEG c
CC6
SEG b
SEG a
LED Digit 7
SEG dp
SEG g
SEG f
SEG e
SEG d
SEG c
SEG b
CC7
SEG a
Table 2. Serial-Data Format (16 Bits)
D15
D14
D13
D12
D11
D10
D9
D8
ADDRESS
high, the 16 bits in the shift register are parallel loaded
into a 16-bit latch. The 16 bits in the latch are then
decoded to determine and execute the command.
The MAX6950/MAX6951 are written to using the following sequence (Figure 2):
1) Take CLK low.
2) Take CS low. This enables the internal 16-bit shift
register.
3) Clock 16 bits of data in order, D15 first to D0 last,
into DIN, observing the setup and hold times.
4) Take CS high.
CLK and DIN may well be used to transmit data to other
peripherals. The MAX6950/MAX6951 ignore all activity
on CLK and DIN except when CS is low. Data cannot
be read from the MAX6950/MAX6951.
If fewer or greater than 16 bits are clocked into the
MAX6950/MAX6951 between taking CS low and taking
CS high again, the MAX6950/MAX6951 store the last 16
bits received, including the previous transmission(s).
The general case is when n bits (where n > 16) are
transmitted to the MAX6950/MAX6951. The last bits
comprising bits {n-15} to {n} are retained and are parallel loaded into the 16-bit latch as bits D15 to D0,
respectively (Figure 3).
Digit and Control Registers
Table 3 lists the addressable Digit and Configuration
registers. The digit registers are implemented by two
planes of 8-byte dual-port SRAM, P0 and P1.
6
D7
MSB
D6
D5
D4
D3
D2
DATA
D1
D0
LSB
Initial Power-Up
On initial power-up, all control registers are reset, the
display is blanked, and the MAX6950/MAX6951 enter
shutdown mode. Program the display driver prior to display use. Otherwise, it is initially set to scan five digits, it
does not decode data in the data registers, and the
Intensity register is set to its minimum value. Table 4
lists the register status after power-up.
Configuration Register
The configuration register is used to enter and exit shutdown, select the blink rate, globally enable and disable
the blink function, globally clear the digit data, and
reset the blink timing. Bit position D1 should always be
written with a zero when the configuration register is
updated. See Table 5 for configuration register format.
The S bit selects shutdown or normal operation.
The B bit selects the blink rate.
The E bit globally enables or disables the blink function.
The T bit resets the blink timing.
The R bit globally clears the digit data for both planes
P0 and P1 for all digits.
When the MAX6950/MAX6951 are in shutdown mode
(Table 6), the scan oscillator is halted; all segment and
digit drivers are high impedance. Data in the digit and
control registers remains unaltered. Shutdown can be
used to save power. For minimum supply current in
shutdown mode, logic inputs should be at ground or V+
(CMOS-logic levels). The display driver can be pro-
_______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
MAX6950/MAX6951
tCSW
CS
tCL
tCSS
CLK
tDS
DIN
tCH
tCSH
tCP
tDH
D15
D14
D1
D0
Figure 1. Timing Diagram
CS
CLK
D15
DIN
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
Figure 2. Transmission of 16 Bits to the MAX6950/MAX6951
CS
CLK
DIN
BIT1
BIT2
N-15
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
Figure 3 . Transmission of More than 16 Bits to the MAX6950/MAX6951
grammed while in shutdown mode, and shutdown
mode can be overridden by the display test function.
Table 7 lists the blink rate selection format.
If blink is globally enabled by setting the E bit of the
configuration register (Table 8), then the digit data in
both planes P0 and P1 are used to control the display
(Table 9).
When the global blink timing synchronization bit is set,
the multiplex and blink timing counter is cleared on the
rising edge of CS. By setting the T bit in multiple
MAX6950/MAX6951s at the same time (or in quick succession), the blink timing can be synchronized across
all the devices.
When the global digit data clear (R data bit D5) is set,
the digit data for both planes P0 and P1 for ALL digits
is cleared on the rising edge of CS. Digits with decode
enabled display the zero. Digits without decode
enabled show all segments unlit.
_______________________________________________________________________________________
7
MAX6950/MAX6951
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
Table 3. Register Address Map
COMMAND ADDRESS
D15
D14
D13
D12
D11
D10
D9
D8
HEX
CODE
No-Op
0
0
0
0
0
0
0
0
0x00
Decode Mode
0
0
0
0
0
0
0
1
0x01
Intensity
0
0
0
0
0
0
1
0
0x02
REGISTER
Scan Limit
0
0
0
0
0
0
1
1
0x03
Configuration
Factory reserved. Do not write to this.
0
0
0
0
0
1
0
0
0x04
0
0
0
0
0
1
1
0
0x06
Display Test
0
0
0
0
0
1
1
1
0x07
Digit 0 plane P0 only (plane 1 unchanged)
0
0
1
0
0
0
0
0
0x20
Digit 1 plane P0 only (plane 1 unchanged)
0
0
1
0
0
0
0
1
0x21
Digit 2 plane P0 only (plane 1 unchanged)
0
0
1
0
0
0
1
0
0x22
Digit 3 plane P0 only (plane 1 unchanged)
0
0
1
0
0
0
1
1
0x23
Digit 4 plane P0 only (plane 1 unchanged)
0
0
1
0
0
1
0
0
0x24
Digit 5 plane P0 only (plane 1 unchanged)
0
0
1
0
0
1
0
1
0x25
Digit 6 plane P0 only (plane 1 unchanged)
0
0
1
0
0
1
1
0
0x26
Digit 7 plane P0 only (plane 1 unchanged)
0
0
1
0
0
1
1
1
0x27
Digit 0 plane P1 only (plane 0 unchanged)
0
1
0
0
0
0
0
0
0x40
Digit 1 plane P1 only (plane 0 unchanged)
0
1
0
0
0
0
0
1
0x41
Digit 2 plane P1 only (plane 0 unchanged)
0
1
0
0
0
0
1
0
0x42
Digit 3 plane P1 only (plane 0 unchanged)
0
1
0
0
0
0
1
1
0x43
Digit 4 plane P1 only (plane 0 unchanged)
0
1
0
0
0
1
0
0
0x44
Digit 5 plane P1 only (plane 0 unchanged)
0
1
0
0
0
1
0
1
0x45
Digit 6 plane P1 only (plane 0 unchanged)
0
1
0
0
0
1
1
0
0x46
Digit 7 plane P1 only (plane 0 unchanged)
0
1
0
0
0
1
1
1
0x47
Digit 0 plane P0 and plane P1 (with same data)
0
1
1
0
0
0
0
0
0x60
Digit 1 plane P0 and plane P1 (with same data)
0
1
1
0
0
0
0
1
0x61
Digit 2 plane P0 and plane P1 (with same data)
0
1
1
0
0
0
1
0
0x62
Digit 3 plane P0 and plane P1 (with same data)
0
1
1
0
0
0
1
1
0x63
Digit 4 plane P0 and plane P1 (with same data)
0
1
1
0
0
1
0
0
0x64
Digit 5 plane P0 and plane P1 (with same data)
0
1
1
0
0
1
0
1
0x65
Digit 6 plane P0 and plane P1 (with same data)
0
1
1
0
0
1
1
0
0x66
Digit 7 plane P0 and plane P1 (with same data)
0
1
1
0
0
1
1
1
0x67
No-Op Register
Display-Test Register
The no-op register is used when the MAX6950/
MAX6951 are connected as the last device on a chain
of cascaded SPI devices. To write the other cascaded
device(s), ensure that while the intended device
receives its specific command, the MAX6950/MAX6951
receive a no-op command.
The display-test register switches the drivers between
one of two modes: normal and display test. Display-test
mode turns all LEDs on by overriding, but not altering,
all control and digit registers (including the Shutdown
register) In display-test mode, eight digits are scanned
and the duty cycle is 7/16 (half power). Table 11 lists
the display-test register format.
8
_______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
MAX6950/MAX6951
Table 4. Initial Power-Up Register Status
REGISTER
POWER-UP CONDITION
ADDRESS
CODE (HEX)
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
Decode
No decode for digits 7–0
0x01
0
0
0
0
0
0
0
0
Intensity
1/16 (min on)
0x02
X
X
X
X
0
0
0
0
Display 5 digits: 0 1 2 3 4
0x03
X
X
X
X
X
1
0
0
Configuration
Shutdown enabled/blink
speed is slow/blink disabled
0x04
X
X
X
0
0
0
0
0
Display Test
Normal operation
0x07
X
X
X
X
X
X
X
0
Digit 0
Blank digit, both planes
0x60
0
0
0
0
0
0
0
0
Digit 1
Blank digit, both planes
0x61
0
0
0
0
0
0
0
0
Digit 2
Blank digit, both planes
0x62
0
0
0
0
0
0
0
0
Digit 3
Blank digit, both planes
0x63
0
0
0
0
0
0
0
0
Digit 4
Blank digit, both planes
0x64
0
0
0
0
0
0
0
0
Digit 5
Blank digit, both planes
0x65
0
0
0
0
0
0
0
0
Digit 6
Blank digit, both planes
0x66
0
0
0
0
0
0
0
0
Digit 7
Blank digit, both planes
0x67
0
0
0
0
0
0
0
0
Scan Limit
Scan-Limit Register
Decode Mode Register
The scan-limit register sets how many digits are displayed, from one to eight digits. It is possible to set the
MAX6950 (the five-digit part) to scan six, seven, or
eight digits. The MAX6951 set to eight digits displays
five digits less brightly than if it had been set to scan
five digits, but the brightness would match that of a
MAX6951 used in the same system if the Intensity registers are set to the same value. For example, consider
an 11-digit requirement. This can be served by using a
MAX6950 to drive five digits plus a MAX6951 to drive
six digits. Both parts are configured to drive six digits to
ensure the brightness is the same.
The decode mode register sets hexadecimal code
(0–9, A–F) or no-decode operation for each digit. Each
bit in the register corresponds to one digit. A logic high
selects hexadecimal code font decoding for that digit,
while logic low bypasses the decoder. Digits may be
set for decode or no-decode in any combination.
Examples of the decode mode control register format
are shown in Table 14.
When the hexadecimal code-decode mode is used, the
decoder looks only at the lower nibble of the data in the
digit register (D3–D0), disregarding bits D6–D4. D7,
which sets the decimal point (SEG DP), is independent
of the decoder, and is positive logic (D7 = 1 turns the
decimal point on). Table 15 lists the hexadecimal code
font. When no-decode is selected, data bits D7–D0 correspond to the segment lines of the MAX6950/
MAX6951. Table 15 shows the one-to-one pairing of
each data bit to the appropriate segment line.
The digits are displayed in a multiplexed manner with a
typical display scan rate of 1kHz with five digits displayed or 625Hz with eight digits displayed with fOSC =
4MHz. Since the number of scanned digits affects the
display brightness, the Scan-Limit register should not
be used to blank portions of the display (such as for
leading-zero suppression). Table 12 lists the scan-limit
register format.
Intensity Register
Digital control of display brightness is provided by an
internal pulse-width modulator, which is controlled by the
lower nibble of the intensity register (Figure 4). The modulator scales the average segment current in 16 steps
from a minimum of 15/16 down to 1/16 of the peak current. The minimum interdigit blanking time is set to 1/16
of a cycle. See Table 13 for Intensity register format.
Display Digit Registers
The MAX6950/MAX6951 use a digit register to store the
data that the user wishes to display on the LED digits.
These digit registers are implemented by two planes of
8-byte, dual-port SRAM, called P0 and P1. The digit
registers are dual port to enable them to be written to
through the SPI interface, asynchronous to being read
to multiplex the display.
_______________________________________________________________________________________
9
MAX6950/MAX6951
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
Table 5. Configuration Register Format
REGISTER DATA
MODE
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
Configuration register
0x04
X
X
R
T
E
B
0
S
D0
Table 6. Shutdown Control (S Data Bit D0) Format
REGISTER DATA
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
Shutdown
0x04
X
X
R
T
E
B
0
0
Normal operation
0x04
X
X
R
T
E
B
0
1
MODE
Table 7. Blink Rate Selection (B Data Bit D2) Format
REGISTER DATA
MODE
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
Slow-blinking segments
blink on for 1s, off for 1s
with fOSC = 4MHz
0x04
X
X
R
T
E
0
0
S
Fast-blinking segments
blink on for 0.5s, off for
0.5s with fOSC = 4MHz
0x04
X
X
R
T
E
1
0
S
Table 8. Global Blink Enable/Disable (E Data Bit D3) Format
REGISTER DATA
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
Blink function is
disabled
0x04
X
X
R
T
0
B
0
S
Blink function is
enabled
0x04
X
X
R
T
1
B
0
S
MODE
Table 9. Global Blink Timing Synchronization (T Data Bit D4) Format
REGISTER DATA
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
Blink timing counters
are unaffected
0x04
X
X
R
0
E
B
0
S
Blink timing counters
are cleared on the
rising edge of CS
0x04
X
X
R
1
E
B
0
S
MODE
Each LED digit is represented by 2 bytes of memory, 1
byte in plane P0 and the other in plane P1. Each LED
digit’s segment is represented by 2 bits of memory, 1
bit from the appropriate byte in each plane. The digit
10
registers are mapped so that a digit’s data can be
updated in plane P0, or plane P1, or both planes at the
same time (Table 3).
______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
MAX6950/MAX6951
Table 10. Global Clear Digit Data (R Data Bit D5) Format
REGISTER DATA
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
Digit data for both
planes P0 and P1 are
unaffected
0x04
X
X
0
T
E
B
0
S
Digit data for both
planes P0 and P1 are
cleared on the rising
edge of CS
0x04
X
X
1
T
E
B
0
S
MODE
Table 11. Display-Test Register Format
REGISTER DATA
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
Normal operation
0x07
X
X
X
X
X
X
X
0
Display test
0x07
X
X
X
X
X
X
X
1
MODE
Table 12. Scan-Limit Register Format
REGISTER DATA
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
HEX
CODE
Display digit 0 only
0x03
X
X
X
X
X
0
0
0
0xX0
Display digits 0 and 1
0x03
X
X
X
X
X
0
0
1
0xX1
Display digits 0 and 1 2
0x03
X
X
X
X
X
0
1
0
0xX2
Display digits 0 and 1 2 3
0x03
X
X
X
X
X
0
1
1
0xX3
Display digits 0 and 1 2 3 4
0x03
X
X
X
X
X
1
0
0
0xX4
Display digits 0 and 1 2 3 4 5
0x03
X
X
X
X
X
1
0
1
0xX5
SCAN LIMIT
Display digits 0 and 1 2 3 4 5 6
0x03
X
X
X
X
X
1
1
0
0xX6
Display digits 0 and 1 2 3 4 5 6 7
0x03
X
X
X
X
X
1
1
1
0xX7
If the blink function is disabled through the Blink Enable
Bit E (Table 8) in the configuration register, then the digit
register data in plane P0 is used to multiplex the display.
The digit register data in P1 is not used (Table 17).
If the blink function is enabled, then the digit register
data in both plane P0 and plane P1 are alternately used
to multiplex the display. Blinking is achieved by multiplexing the LED display using data plane P0 and plane
P1 on alternate phases of the blink clock (Table 18).
on and off. Once blinking has been configured, it continues automatically without further intervention.
Display Blink Mode
The OSC input pin is used to set both the display scan
rate and the blink timing for the display driver. OSC
must either be fitted with an external capacitor CSET to
GND to set the frequency of the MAX6950/MAX6951s’
internal RC oscillator, or be overdriven with an external
TTL/CMOS clock.
The display blinking facility, when enabled, makes the
driver flip automatically between displaying the digit
register data in planes P0 and plane P1. If the digit register data for any individual segment is different in the
two planes, then that segment appears to blink or flash
Blink Speed
The blink speed is determined by frequency of the multiplex clock, OSC, and by the setting of the Blink Rate
Selection Bit B (Table 7) in the configuration register.
The Blink Rate Selection Bit B sets either fast or slow
blink speed for the whole display.
Multiplex Clock and OSC Oscillator
______________________________________________________________________________________
11
MAX6950/MAX6951
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
Table 13. Intensity Register Format
DUTY CYCLE
TYPICAL SEGMENT
CURRENT (mA)
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
HEX
CODE
1/16 (min on)
2.5
0x02
X
X
X
X
0
0
0
0
0xX0
2/16
5
0x02
X
X
X
X
0
0
0
1
0xX1
3/16
7.5
0x02
X
X
X
X
0
0
1
0
0xX2
4/16
10
0x02
X
X
X
X
0
0
1
1
0xX3
5/16
12.5
0x02
X
X
X
X
0
1
0
0
0xX4
6/16
15
0x02
X
X
X
X
0
1
0
1
0xX5
7/16
17.5
0x02
X
X
X
X
0
1
1
0
0xX6
8/16
20
0x02
X
X
X
X
0
1
1
1
0xX7
9/16
22.5
0x02
X
X
X
X
1
0
0
0
0xX8
10/16
25
0x02
X
X
X
X
1
0
0
1
0xX9
11/16
27.5
0x02
X
X
X
X
1
0
1
0
0xXA
12/16
30
0x02
X
X
X
X
1
0
1
1
0xXB
13/16
32.5
0x02
X
X
X
X
1
1
0
0
0xXC
14/16
35
0x02
X
X
X
X
1
1
0
1
0xXD
15/16
37.5
0x02
X
X
X
X
1
1
1
0
0xXE
15/16 (max on)
37.5
0x02
X
X
X
X
1
1
1
1
0xXF
The allowed range of the frequency at the OSC pin, fOSC,
is 1MHz to 8MHz, which allows the blink frequency to be
adjusted over a wide range. The internal oscillator may
be accurate enough for many applications using a single
device. If an exact or synchronized blink rate is required,
then OSC should be driven by an external clock.
The display scan rate (defined in the Electrical
Characteristics table) is calculated by dividing fOSC by
4000 for the MAX6950 (scanning a full five digits), or by
6400 for the MAX6951 (scanning a full eight digits). The
display scan rate is the refresh rate for all the digits of the
display. With fOSC at 4MHz, each display digit is enabled
for 200µs.
There is a fail-safe circuit in the MAX6950/MAX6951 to
ensure the display multiplexing works if the OSC is configured incorrectly. This ensures that the driver cannot
remain stuck on a single digit, forcing a peak current continuously through segments. The fail-safe circuit detects
that fOSC is too slow, and generates extra clock transitions to guarantee a minimum effective clock of typically
75.5kHz. The scan rate for eight digits is about 11Hz in
fail-safe mode, and appears to flicker to most observers.
A flickering display is a good indication that there is a
problem with the multiplex clock. The clock failure detection works regardless of the clock source being the internal RC oscillator or external clock drive.
12
The RC oscillator uses an external resistor RSET (which
also sets the peak segment current) and an external
capacitor CSET to set the oscillator frequency. The recommended values of RSET and CSET set the oscillator at
4MHz, which makes the slow and fast blink frequency
0.5Hz and 1Hz, respectively.
Synchronization of Blinking Across
Multiple MAX6950/MAX6951 Drivers
The OSC inputs of multiple MAX6950/MAX6951 drivers
can be connected together to an external clock to make
the devices blink at the same frequency. Segment blinking may be synchronized across multiple MAX6950/
MAX6951s so that all drivers blink not only at the same
frequency, but also in phase. When the control register is
written with the T bit set (Table 9), the OSC divider chain
is cleared and the display multiplexing sequence reset.
To synchronize several drivers, it is necessary to write
this register in all drivers at the same time. In practice,
adequate synchronization can be achieved by writing to
multiple drivers in quick succession.
When the global blink timing synchronization bit is set,
the multiplexing and blink counter is cleared on the rising edge of CS. By setting the T bit in multiple
MAX6950/MAX6951s at the same time (or in quick succession), the blink timing can be synchronized across
all the devices. Note that the display multiplexing
______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
MAX6950/MAX6951
START OF NEXT
ONE COMPLETE 1.6ms MULTIPLEX CYCLE AROUND 8 DIGITS
CYCLE
200µs TIME SLOT
DIGIT 0
200µs TIME SLOT
DIGIT 1
200µs TIME SLOT
DIGIT 2
DIGIT CATHODE
DRIVER INTENSITY
SETTINGS
200µs TIME SLOT
DIGIT 3
200µs TIME SLOT
DIGIT 4
200µs TIME SLOT
DIGIT 5
200µs TIME SLOT
DIGIT 6
200µs TIME SLOT
DIGIT 7
200µs TIME SLOT
DIGIT 0
DIGIT 0's 200µs MULTIPLEX TIME SLOT
HIGH-Z
1/16TH
(MIN ON)
LOW
CURRENT SOURCE ENABLED
ANODE
MIN ON
HIGH-Z
HIGH-Z
HIGH-Z
2/16TH
LOW
HIGH-Z
3/16TH
LOW
HIGH-Z
13/16TH
LOW
HIGH-Z
14/16TH
LOW
HIGH-Z
15/16TH
LOW
HIGH-Z
16/16TH
MAX ON
LOW
MINIMUM 12.5µs INTERDIGIT BLANKING INTERVAL
CURRENT SOURCE ENABLED
ANODE
MAX ON
HIGH-Z
HIGH-Z
ANODE (UNLIT)
HIGH-Z
HIGH-Z
Figure 4. Multiplex and Intensity Timing Diagram
______________________________________________________________________________________
13
MAX6950/MAX6951
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
Table 14. Decode-Mode Register Examples
REGISTER DATA
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
HEX
CODE
No decode for digits 7–0
0x01
0
0
0
0
0
0
0
0
0x00
Hexadecimal decode for digit 0,
no decode for digits 7–1
0x01
0
0
0
0
0
0
0
1
0x01
Hexadecimal decode for digits
2–0, no decode for digits 7–3
0x01
0
0
0
0
0
1
1
1
0x07
Hexadecimal decode for digits
7–0
0x01
1
1
1
1
1
1
1
1
0xFF
DECODE CODE
Table 15. Hexadecimal Font
7-SEGMENT
CHARACTER
REGISTER DATA
D7*
ON SEGMENTS = 1
D6–D4
D3
D2
D1
D0
0
X
0
0
0
1
X
0
0
2
X
0
0
3
X
0
4
X
5
X
6
dp*
a
b
c
d
e
f
g
0
1
1
1
1
1
1
0
0
1
0
1
1
0
0
0
0
1
0
1
1
0
1
1
0
1
0
1
1
1
1
1
1
0
0
1
0
1
0
0
0
1
1
0
0
1
1
0
1
0
1
1
0
1
1
0
1
1
X
0
1
1
0
1
0
1
1
1
1
1
7
X
0
1
1
1
1
1
1
0
0
0
0
8
X
1
0
0
0
1
1
1
1
1
1
1
9
X
1
0
0
1
1
1
1
1
0
1
1
A
X
1
0
1
0
1
1
1
0
1
1
1
B
X
1
0
1
1
0
0
1
1
1
1
1
C
X
1
1
0
0
1
0
0
1
1
1
0
D
X
1
1
0
1
0
1
1
1
1
1
1
E
X
1
1
1
0
1
0
0
1
1
1
1
F
X
1
1
1
1
1
0
0
0
1
1
1
The decimal point segment is lit when bit D7 = 1.
sequence is also reset, which might give rise to a onetime display flicker when the register is written.
Selecting External Components RSET
and CSET to Set Oscillator Frequency
and Segment Current
The RC oscillator uses an external resistor RSET and an
external capacitor CSET to set the oscillator frequency,
fOSC. The allowed range of fOSC is 1MHz to 8MHz.
RSET also sets the peak segment current. The recommended values of RSET and CSET set the oscillator to
14
4MHz, which makes the blink frequencies 0.5Hz and
1Hz. The recommended value of RSET also sets the
peak current to 40mA, which makes the segment current adjustable from 2.5mA to 37.5mA in 2.5mA steps.
ISEG = KI / RSET mA
fOSC = KF / (RSET ✕ CSET + CSTRAY) MHz
Where:
KI = 2240
______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
REGISTER DATA
Segment line
D7
D6
D5
D4
D3
D2
D1
D0
dp
a
b
c
d
e
f
g
a
f
b
g
e
c
d
d
KF = 6720
RSET = external resistor in kΩ
CSET = external capacitor in pF
CSTRAY = stray capacitance from OSC pin to GND in
pF, typically 3pF
The recommended value of RSET is 56kΩ and the recommended value of CSET is 27pF.
The recommended value of R SET is the minimum
allowed value, since it sets the display driver to the
maximum allowed segment current. RSET can be set to
a higher value to set the segment current to a lower
peak value where desired. The user must also ensure
that the peak current specifications of the LEDs connected to the driver are not exceeded.
The effective value of CSET includes not only the actual
external capacitor used, but also the stray capacitance
from the OSC pin to GND. This capacitance is usually
in the 1pF to 5pF range, depending on the layout used.
LED Maximum Reverse Voltage
The display connection scheme used by the
MAX6950/MAX6951 puts LED segments in reverse bias
during a portion of the multiplexing time. The maximum
applied reverse bias voltage is the value of the supply
voltage, V+. It is therefore important to ensure that the
LEDs chosen are rated to withstand a reverse bias
equal to the maximum supply voltage applied to the
MAX6950/MAX6951.
Applications Information
Choosing Supply Voltage to Minimize
Power Dissipation
The MAX6950/MAX6951 drive a peak current of 40mA
into LEDs with a 2.4V forward-voltage drop when operated from a supply voltage of at least 3.0V. The minimum voltage drop across the internal LED drivers is
therefore (3.0V - 2.4V) = 0.6V. If a higher supply voltage is used, the driver absorbs a higher voltage, and
the driver’s power dissipation increases accordingly.
However, if the LEDs used have a higher forward voltage drop than 2.4V, the supply voltage must be raised
accordingly to ensure that the driver always has at least
0.6V headroom.
The voltage drop across the drivers with a nominal +5V
supply (5.0V - 2.4V) = 2.6V is nearly 3 times the drop
across the drivers with a nominal 3.3V supply (3.3V 2.4V) = 0.9V. In many systems, consumption is an
important design criterion, and the MAX6950/MAX6951
should be operated from the system’s 3.3V nominal
supply. In other designs, the lowest supply voltage may
be 5V. The issue now is to ensure the dissipation limit
for the MAX6950/MAX6951 is not exceeded. This can
be achieved by inserting a series resistor in the supply
to the MAX6950/MAX6951, ensuring that the supply
decoupling capacitors are still on the MAX6950/
MAX6951 side of the resistor. For example, consider
the requirement that the minimum supply voltage to a
MAX6951 must be 3.0V, and the input supply range is
5V ±5%. Maximum supply current is 15mA + (40mA ✕
8) = 335mA. Minimum input supply voltage is 4.75V.
Maximum series resistor value is (4.75V - 3.0V)/0.335A
= 5.2Ω. We choose 4.7Ω ±10%. Worst-case resistor
dissipation is at maximum toleranced resistance, i.e.,
(0.335A)2 ✕ (4.7Ω ✕ 1.1) = 0.584W. We choose a 1W
resistor rating. The maximum MAX6951 supply voltage
is at maximum input supply voltage and minimum toleranced resistance, i.e., 5.25V - (0.335A ✕ 4.7Ω ✕ 0.9) =
3.83V.
Low-Voltage Operation
The MAX6950/MAX6951 work over the +2.7V to +5.5V
supply range. The minimum useful supply voltage is
determined by the forward voltage drop of the LEDs at
the peak current ISEG, plus the 0.6V headroom required
by the driver output stages. The MAX6950/MAX6951
correctly regulate ISEG with a supply above this minimum voltage. If the supply drops below this minimum
voltage, the driver output stages may brown out, and
______________________________________________________________________________________
15
MAX6950/MAX6951
Table 16. No-Decode Mode Data Bits and
Corresponding Segment Lines
MAX6950/MAX6951
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
Table 17. Digit Register Mapping with
Blink Globally Disabled
SEGMENT’S
BIT SETTING
IN PLANE P1
SEGMENT’S
BIT SETTING
IN PLANE P0
X
0
X
1
SEGMENT
BEHAVIOR
Segment off during both
halves of each blink
period
Segment off during both
halves of each blink
period
V+ = supply voltage
DUTY = duty cycle set by intensity register
N = number of segment driven (worst case is 8)
VLED = LED forward voltage
ISEG = segment current set by RSET
PD = power dissipation, in mW if currents are in mA
Dissipation example:
ISEG = 40mA, N = 8, Duty = 15/16, VLED = 2.4V at
40mA, V+ = 3.6V
PD = 3.6V (15mA) + (3.6V - 2.4V)(15 / 16 ✕ 40mA x 8)
= 0.414W
Table 18. Digit Register Mapping with
Blink Globally Enabled
SEGMENT’S
BIT SETTING
IN PLANE P1
SEGMENT’S
BIT SETTING
IN PLANE P0
0
0
Segment off
1
Segment on only during
the 1st half of each blink
period
1
0
Segment on only during
the 2nd half of each blink
period
1
1
Segment on
0
SEGMENT
BEHAVIOR
be unable to regulate the current correctly. As the supply voltage drops further, the LED segment drive current becomes effectively limited by the output drivers'
on-resistance, and the LED drive current drops. The
characteristics of each individual LED in a modern 7segment digit usually match well, so the result is that
the display intensity dims uniformly as supply voltage
drops out of regulation and beyond. The MAX6950/
MAX6951 operate down to 2V supply voltage (although
most displays are very dim at this voltage), providing
that the MAX6950/MAX6951 are powered up initially to
at least 2.7V to trigger the device's internal reset, and
also that the SPI interface is constrained to 5Mbps.
Computing Power Dissipation
The upper limit for power dissipation (PD) for the
MAX6950/MAX6951 is determined from the following
equation:
Thus, for the 16-pin QSOP package (TJA = 1/0.00834 =
+120°C/W), the maximum allowed ambient temperature
TA is given by:
TJ (MAX) = TA + (PD ✕ TJA) = +150°C = TA + (0.44 ✕
+120°C/W)
So TA = +100°C. Thus, the device can be operated
safely at a maximum package temperature of +85°C.
Power Supplies
The MAX6950/MAX6951 operate from a single +2.7V to
+5.5V power supply. Bypass the power supply to
ground with a 0.1µF capacitor as close to the pin as
possible. Add a 22µF capacitor if the MAX6950/
MAX6951 are not close to the board’s input bulk decoupling capacitor.
Board Layout
When designing a board, use the following guidelines:
1. The RSET connection to pin 7 is a high-impedance
node, and sensitive to layout. Place RSET right next
to pins 7 and 8 and route RSET directly to these pins
with very short tracks.
2. Ensure that the track from the ground end of RSET
routes directly to pin 8, and that this track is not
used as part of any other ground connection.
Figure 5 shows a good layout. The decoupling capacitors C1 (ceramic) and C2 (bulk, if required) are located
above the IC. The ground track to RSET is a separate
track from both the IC's power ground connection and
the ground plane.
PD = (V+ x I+) + (V+ - VLED) (DUTY ✕ ISEG ✕ N)
Where:
16
______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
3.3V
C2
22µF
C1
100nF
16
9
DIG1–DIG8
SEG1–SEG9
8 DIGITS
AND SEGMENTS
(SEE TABLE 1 FOR CONNECTIONS)
MAX6951
µC
ISET
DIN
CS
CLK
1
15
2
7
DIN
RSET
56kΩ
CS
OSC
CLK
9
CSET
27pF
8
Chip Information
TRANSISTOR COUNT: 17,350
PROCESS: CMOS
Figure 5. Sample Board Layout
______________________________________________________________________________________
17
MAX6950/MAX6951
Typical Application Circuit
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
MAX6950/MAX6951
Functional Diagram
8 CATHODE DRIVERS
9 ANODE DRIVERS
DIG0/SEG0
SEGMENT
CURRENT
REFERENCE
ISET
PWM
BRIGHTNESS
CONTROL
HEXADECIMAL
ROM
OUT
IN MODE
8
MULTIPLEX, PWM BLINK
COUNTERS
OSC
3
BLINK ENABLE REGISTER
BLINK RATE
BLINK RATE REGISTER
BLINK SYNC
BLINK SYNC REGISTER
P1 ENABLE
P0 ENABLE
(DIG5)/SEG5
(DIG6)/SEG6
(DIG7)/SEG7
DIGIT
SEG8
SHUTDOWN
TEST
DIGIT
MULTIPLEXER
BLINK ENABLE
BLINK CONTROL
PWM
INTENSITY REGISTER
DECODE-MODE REGISTER
GLOBAL CLEAR REGISTER
SCAN-LIMIT REGISTER
3
3
8
ENABLE ADDRESS
DATA
ENABLE ADDRESS
CLR
8-BYTE DUAL-PORT RAM
PLANE P0
DATA ADDRESS
ENABLE
8
SHUTDOWN REGISTER
8
DATA
CLR
TEST REGISTER
8-BYTE DUAL-PORT RAM
PLANE P1
DATA ADDRESS
ENABLE
8
3
CONFIGURATION REGISTER
DATA
8
3
ENABLE
DIGIT AND CONTROL REGISTER
ADDRESS DECODER
8
REGISTER ADDRESS
REGISTER DATA
DIGIT/CONTROL
ADDRESS
0
0
0
DIGIT
PLANE
0
CS
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
DIN
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
CLK
18
DIG1/SEG1
DIG2/SEG2
DIG3/SEG3
DIG4/SEG4
______________________________________________________________________________________
Serially Interfaced, +2.7V to +5.5V,
5- and 8-Digit LED Display Drivers
QSOP.EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
MAX6950/MAX6951
Package Information