MAXIM MAX6954AAX

19-2460; Rev 4; 3/09
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
The MAX6954 is a compact display driver that interfaces microprocessors to a mix of 7-segment, 14-segment, and 16-segment LED displays through an SPI™or QSPI™-compatible 4-wire serial interface. The serial
interface may be cascaded through multiple devices.
The MAX6954 drives up to 16 digits 7-segment, 8 digits
14-segment, 8 digits 16-segment, or 128 discrete
LEDs, while functioning from a supply voltage as low as
2.7V. The driver includes five I/O expander (or GPIO)
lines, some or all of which may be configured as a keyswitch reader, which automatically scans and
debounces a matrix of up to 32 switches.
Included on chip are full 14- and 16-segment ASCII
104-character fonts, a hexadecimal font for 7-segment
displays, multiplex scan circuitry, anode and cathode
drivers, and static RAM that stores each digit. The maximum segment current for the display digits is set using
a single external resistor. Digit intensity can be independently adjusted using the 16-step internal digital
brightness control. The MAX6954 includes a low-power
shutdown mode, a scan-limit register that allows the
user to display from 1 to 16 digits, segment blinking
(synchronized across multiple drivers, if desired), and a
test mode, which forces all LEDs on. The LED drivers
are slew-rate limited to reduce EMI.
For a 2-wire interfaced version, refer to the MAX6955
data sheet. An evaluation kit (EV kit) for the MAX6955 is
available.
Features
♦ High-Speed 26MHz SPI/QSPI/MICROWIRE™Compatible Serial Interface
♦ 2.7V to 5.5V Operation
♦ Drives Up to 16 Digits 7-Segment, 8 Digits
14-Segment, 8 Digits 16-Segment, 128 Discrete
LEDs, or a Combination of Digit Types
♦ Drives Common-Cathode Monocolor and Bicolor
LED Displays
♦ Built-In ASCII 104-Character Font for 14-Segment
and 16-Segment Digits and Hexadecimal Font for
7-Segment Digits
♦ Automatic Blinking Control for each Segment
♦ 10µA (typ) Low-Power Shutdown (Data Retained)
♦ 16-Step Digit-by-Digit Digital Brightness Control
♦ Display Blanked on Power-Up
♦ Slew-Rate Limited Segment Drivers for Lower EMI
♦ Five GPIO Port Pins Can Be Configured as KeySwitch Reader to Scan and Debounce Up to 32
Switches with n-Key Rollover
♦ IRQ Output when a Key Input Is Debounced
♦ 36-Pin SSOP and 40-Pin DIP and TQFN Packages
♦ Automotive Temperature Range Standard
Functional Diagram
Applications
Set-Top Boxes
Automotive
Panel Meters
Bar Graph Displays
White Goods
Audio/Video Equipment
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX6954AAX
-40°C to +125°C
36 SSOP
MAX6954APL
-40°C to +125°C
40 PDIP
MAX6954ATL+
-40°C to +125°C
40 TQFN-EP*
ISET
OSC
OSC_OUT
MICROWIRE is a trademark of National Semiconductor Corp.
PWM
BRIGHTNESS
CONTROL
CURRENT
SOURCE
BLINK
O0 TO O23
CHARACTER
GENERATOR
ROM
BLINK
CONTROL
RAM
CLK
CS
DIN
DOUT
LED
DRIVERS
DIGIT
MULTIPLEXER
DIVIDER/
COUNTER
NETWORK
MAX6954
+Denotes a lead-free/RoHS-compliant package.
*EP = Exposed pad.
Pin Configurations and Typical Operating Circuits appear
at end of data sheet.
SPI and QSPI are trademarks of Motorola, Inc.
P0 TO P4
GPIO
AND KEY-SCAN
CONTROL
CONFIGURATION
REGISTER
4-WIRE SERIAL INTERFACE
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX6954
General Description
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
ABSOLUTE MAXIMUM RATINGS
(Voltage with respect to GND.)
V+ .........................................................................-0.3V to +6V
All Other Pins............................................-0.3V to (V+ + 0.3V)
Current
O0–O7 Sink Current ......................................................935mA
O0–O18 Source Current .................................................55mA
DIN, CLK, CS, OSC, DOUT, BLINK, OSC_OUT, ISET ....20mA
P0, P1, P2, P3, P4 ...........................................................40mA
GND .....................................................................................1A
Continuous Power Dissipation (TA = +70°C)
36-Pin SSOP (derate at 11.8mW/°C above +70°C) .....941mW
40-Pin PDIP (derate at 16.7mW/°C above +70°C).....1333mW
40-Pin TQFN (derate at 37mW/°C above +70°C) ......2963mW
Operating Temperature Range
(TMIN to TMAX) ...............................................-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
(Typical Operating Circuits, V+ = 2.7V 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
Master Clock Frequency
I+
fOSC
CONDITIONS
MIN
TYP
2.7
Shutdown mode, all
digital inputs at V+
or GND
All segments on, all
digits scanned,
intensity set to full,
internal oscillator,
DOUT open circuit,
no display or
OSC_OUT load
connected
TA = +25°C
10
MAX
UNITS
5.5
V
35
µA
TA = TMIN to TMAX
40
TA = +25°C
22
30
mA
TA = TMIN to TMAX
35
OSC = RC oscillator, RSET = 56kΩ,
CSET = 22pF, V+ = 3.3V
OSC driven externally
4
1
MHz
8
Dead Clock Protection Frequency
fOSC
95
kHz
OSC Internal/External Detection
Threshold
VOSC
1.7
V
OSC High Time
tCH
50
ns
OSC Low Time
tCL
50
ns
Slow Segment Blink Period
OSC = RC oscillator, RSET = 56kΩ,
fSLOWBLINK C
SET = 22pF, V+ = 3.3V
Fast Segment Blink Period
fFASTBLINK
Fast or Slow Segment Blink Duty
Cycle
2
OSC = RC oscillator, RSET = 56kΩ,
CSET = 22pF, V+ = 3.3V
1
s
0.5
s
49.5
_______________________________________________________________________________________
50.5
%
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
(Typical Operating Circuits, V+ = 2.7V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 1)
PARAMETER
Segment Drive Source Current
Segment Current Slew Rate
Segment Drive Current Matching
SYMBOL
ISEG
CONDITIONS
VLED = 2.2V,
V+ = 3.3V
TA = +25°C
MIN
TYP
MAX
UNITS
-34.5
-40
-46.5
mA
ΔISEG/Δt
TA = +25°C, V+ = 3.3V
11
ΔISEG
TA = +25°C, V+ = 3.3V
5
mA/µs
10
%
+1
µA
LOGIC INPUTS AND OUTPUTS
Input Leakage Current
DIN, CLK, CS, OSC, P0, P1, P2,
P3, P4
IIH, IIL
-1
4-Wire Logic-High Input Voltage
DIN, CLK, CS
VIHSPI
1.8
4-Wire Logic-Low Input Voltage
DIN, CLK, CS
VILSPI
Port Logic-High Input Voltage
P0, P1, P2, P3, P4
VIHP
Port Logic-Low Input Voltage
P0, P1, P2, P3, P4
VILP
Port Hysteresis Voltage P0, P1,
P2, P3, P4
ΔVIP
Port Input Pullup Current from V+
IIPU
V
0.6
0.7 x
V+
V
V
0.3 x
V+
V
0.03 x
V+
V
P0 to P3 configured as keyscan input, V+ =
3.3V
75
µA
Port Output Low Voltage
VOLP
ISINK = 8mA
0.3
0.5
V
Blink Output Low Voltage
VOLBK
ISINK = 0.6mA
0.1
0.3
V
DOUT Output High Voltage
VOHDO
ISOURCE = 1.6mA
DOUT Output Low Voltage
VOLDO
ISINK = 1.6mA
OSC_OUT Output High Voltage
VOHOSC
ISOURCE = 1.6mA
OSC_OUT Output Low Voltage
VOLOSC
ISINK = 1.6mA
V+ 0.2
V
0.2
V+ 0.4
V
V
0.4
V
_______________________________________________________________________________________
3
MAX6954
DC ELECTRICAL CHARACTERISTICS (continued)
TIMING CHARACTERISTICS
(Typical Operating Circuits, V+ = 2.7V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
TIMING CHARACTERISTICS
CLK Clock Period
tCP
38.4
ns
CLK Pulse Width High
tCH
16
ns
CLK Pulse Width Low
tCL
16
ns
CS Fall to CLK Rise Setup Time
tCSS
9.5
ns
CLK Rise to CS Rise Hold Time
tCSH
0
ns
DIN Setup Time
tDS
9.5
ns
DIN Hold Time
tDH
Output Data Propagation Delay
0
tDO
DOUT Output Rise and Fall Times
tFT
Minimum CS Pulse High
ns
V+ = 3.0V to 5.5V
19
V+ = 2.7V
25
CLOAD = 10pF, V+ = 3.0V to 5.5V
ns
10
tCSW
19.5
ns
Note 1: All parameters tested at TA = +25°C. Specifications over temperature are guaranteed by design.
Typical Operating Characteristics
(V+ = 3.3V, LED forward voltage = 2.4V, typical application circuit, TA = +25°C, unless otherwise noted.)
4.2
4.0
3.8
RSET = 56kΩ
CSET = 22pF
4.4
MAX6954 toc03
MAX6954 toc02
RSET = 56kΩ
CSET = 22pF
OSCILLATOR FREQUENCY (MHz)
4.4
INTERNAL OSCILLATOR WAVEFORM
AT OSC AND OSC_OUT PINS
INTERNAL OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
MAX6954 toc01
INTERNAL OSCILLATOR FREQUENCY
vs. TEMPERATURE
OSCILLATOR FREQUENCY (MHz)
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
RSET = 56kΩ
CSET = 22pF
OSC
4.2
0V
4.0
OSC_OUT
3.8
0V
3.6
3.6
-40
-10
20
50
TEMPERATURE (°C)
4
80
110
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
100ns/div
OSC: 500mV/div
OSC_OUT: 2V/div
_______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
SEGMENT SOURCE CURRENT
vs. SUPPLY VOLTAGE
DEAD CLOCK OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
105
100
95
90
85
1.02
MAX6954 toc05
RSET = 56kΩ
OSC = GND
CURRENT NORMALIZED TO 40mA
MAX6954 toc04
OSCILLATOR FREQUENCY (kHz)
110
1.00
0.98
0.96
0.94
VLED = 1.8V
0.92
80
3.0
3.5
4.0
4.5
2.5
5.5
5.0
3.0
3.5
4.0
4.5
5.5
5.0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
GPIO SINK CURRENT
vs. TEMPERATURE
WAVEFORM AT PINS O0 AND O18,
MAXIMUM INTENSITY
MAX6954 toc06
45
OUTPUT = LOW
VPORT = 0.6V
GPIO SINK CURRENT (mA)
40
O0
0V
35
MAX6954 toc07
2.5
VCC = 5.5V
30
25
VCC = 3.3V
20
VCC = 2.5V
15
10
O18
5
0V
0
-40
1V/div
200μs/div
50
80
110
KEYSCAN OPERATION
(KEY_A AND IRQ)
OUTPUT = HIGH
VPORT = 1.4V
0.20
MAX6954 toc09
MAX6954 toc08
KEY-SCAN SOURCE CURRENT (mA)
0.30
VCC = 5.5V
20
TEMPERATURE (°C)
PORT INPUT PULLUP CURRENT
vs. TEMPERATURE
0.25
-10
KEY_A
0.15
0V
0.10
VCC = 3.3V
IRQ
0.05
0V
VCC = 2.5V
0
-40
-10
20
50
TEMPERATURE (°C)
80
110
400μs/div
KEY_A: 1V/div
IRQ: 2V/div
_______________________________________________________________________________________
5
MAX6954
Typical Operating Characteristics (continued)
(V+ = 3.3V, LED forward voltage = 2.4V, typical application circuit, TA = +25°C, unless otherwise noted.)
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Pin Description
PIN
NAME
FUNCTION
SSOP
PDIP
TQFN-EP
1, 2,
34, 35, 36
1, 2,
38, 39, 40
36, 37,
33, 34, 35
P0–P4
General-Purpose I/O Ports (GPIOs). GPIO can be configured as logic inputs or
open-drain outputs. Enabling key scanning configures some or all ports P0–P3 as
key-switch matrix inputs with internal pullup and port P4 as IRQ output.
3
3
38
CS
Chip-Select Input. Serial data is loaded into the shift register while CS is low. The
most recent 16 bits of data latch on CS’s rising edge.
4
4
39
DOUT
Serial-Data Output. The data into DIN is valid at DOUT 15.5 clock cycles later. Use
this pin to daisy-chain several devices or allow data readback. Output is push-pull.
5
5
40
CLK
Serial-Clock Input. On CLK’s rising edge, data shifts into the internal shift register. On
CLK’s falling edge, data is clocked out of DOUT. CLK is active only while CS is low.
6
6
1
DIN
Serial-Data Input. Data from DIN loads into the internal 16-bit shift register on CLK’s
rising edge.
7–15,
22–31
7–15,
26–35
2–10,
21–30
O0–O18
16, 18
17, 18, 20
12, 13, 15
GND
Ground
17
19
14
ISET
Segment Current Setting. Connect ISET to GND through series resistor RSET to set
the peak current.
19, 21
21, 23, 24
16, 18, 19
V+
Positive Supply Voltage. Bypass V+ to GND with a 47µF bulk capacitor and a 0.1µF
ceramic capacitor.
20
22
17
OSC
Multiplex Clock Input. To use internal oscillator, connect capacitor CSET from OSC
to GND. To use external clock, drive OSC with a 1MHz to 8MHz CMOS clock.
32
36
31
BLINK
33
37
32
OSC_OUT
—
16, 25
11, 20
N.C.
—
—
—
EP
Digit/Segment Drivers. When acting as digit drivers, outputs O0 to O7 sink current
from the display common cathodes. When acting as segment drivers, O0 to O18
source current to the display anodes. O0 to O18 are high impedance when not
being used as digit or segment drivers.
Blink Clock Output. Output is open drain.
Clock Output. OSC_OUT is a buffered clock output to allow easy blink
synchronization of multiple MAX6954s. Output is push-pull.
Not Connected Internally
Exposed Pad (TQFN package only). Internally connected to GND. Connect to a
large ground plane to maximize thermal performance.
Detailed Description
The MAX6954 is a serially interfaced display driver that
can drive up to 16 digits 7-segment, 8 digits 14-segment, 8 digits 16-segment, 128 discrete LEDs, or a
combination of these display types. Table 1 shows the
drive capability of the MAX6954 for monocolor and
bicolor displays.
The MAX6954 includes 104-character ASCII font maps
for 14-segment and 16-segment displays, as well as
the hexadecimal font map for 7-segment displays. The
characters follow the standard ASCII font, with the addition of the following common symbols: £, €, ¥, °, µ, ±,
↑, and ↓. Seven bits represent the 104-character font
6
map; an 8th bit is used to select whether the decimal
point (DP) is lit. Seven-segment LED digits may be controlled directly or use the hexadecimal font. Direct segment control allows the MAX6954 to be used to drive
bar graphs and discrete LED indicators.
Tables 2, 3, and 4 list the connection schemes for 16-,
14-, and 7-segment digits, respectively. The letters in
Tables 2, 3, and 4 correspond to the segment labels
shown in Figure 1. (For applications that require mixed
display types, see Tables 37–40.)
Serial Interface
The MAX6954 communicates through an SPI-compatible 4-wire serial interface. The interface has three
_______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
1b
1f
2f
2b
1g
1e
a
2a
f
2g
2e
1c
e
m
i
j
f
b
l
k
i
h
g1
g2
2dp
2d
1d
a2
a1
g1
2c
1dp
h
c
e
m
j
b
g2
l
k
c
dp
dp
d2
d
MAX6954
1a
d1
Figure 1. Segment Labeling for 7-Segment Display, 14-Segment Display, and 16-Segment Display
Table 1. MAX6954 Drive Capability
DISPLAY TYPE
7 SEGMENT
(16-CHARACTER
HEXADECIMAL FONT)
14 SEGMENT/
16 SEGMENT
(104-CHARACTER ASCII FONT MAP)
DISCRETE LEDs
(DIRECT CONTROL)
Monocolor
16
8
128
Bicolor
8
4
64
inputs: clock (CLK), chip select (CS), and data in (DIN),
and one output, data out (DOUT). CS must be low to
clock data into or out of the device, and DIN must be
stable when sampled on the rising edge of CLK. DOUT
is stable on the rising edge of CLK. Note that while the
SPI protocol expects DOUT to be high impedance
when the MAX6954 is not being accessed, DOUT on
the MAX6954 is never high impedance.
CLK and DIN may be used to transmit data to other
peripherals. The MAX6954 ignores all activity on CLK
and DIN except when CS is low.
Control and Operation Using the 4-Wire Interface
Controlling the MAX6954 requires sending a 16-bit
word. The first byte, D15 through D8, is the command,
and the second byte, D7 through D0, is the data byte
(Table 5).
Connecting Multiple MAX6954s to the 4-Wire Bus
Multiple MAX6954s may be daisy-chained by connecting the DOUT of one device to the DIN of the next, and
driving CLK and CS lines in parallel (Figure 2). Data at
DIN propagates through the internal shift registers and
appears at DOUT 15.5 clock cycles later, clocked out
on the falling edge of CLK. When sending commands
to daisy-chained MAX6954s, all devices are accessed
at the same time. An access requires (16 x n) clock
cycles, where n is the number of MAX6954s connected
together. To update just one device in a daisy-chain,
the user can send the no-op command (0x00) to the
others. Figure 3 is the MAX6954 timing diagram.
The MAX6954 is written to using the following
sequence:
1) Take CLK low.
2) Take CS low. This enables the internal 16-bit shift
register.
3) Clock 16 bits of data into DIN, D15 first to D0 last,
observing the setup and hold times. Bit D15 is low,
indicating a write command.
4) Take CS high (while CLK is still high after clocking in
the last data bit).
5) Take CLK low.
Figure 4 shows a write operation when 16 bits are
transmitted.
If fewer or greater than 16 bits are clocked into the
MAX6954 between taking CS low and taking CS high
again, the MAX6954 stores the last 16 bits received,
including the previous transmission(s). The general
case is when n bits (where n > 16) are transmitted to
the MAX6954. The last bits are comprising bits {n-15} to
{n}, are retained, and are parallel loaded into the 16-bit
latch as bits D15 to D0, respectively (Figure 5).
_______________________________________________________________________________________
7
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 2. Connection Scheme for Eight 16-Segment Digits
DIGIT O0
O1
O2
O3
O4
O5
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
CCO
—
a1
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
1
—
CC1
a1
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
2
a1
a2
CC2
—
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
3
a1
a2
—
CC3
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
4
a1
a2
b
c
CC4
—
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
5
a1
a2
b
c
—
CC5
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
6
a1
a2
b
c
d1
d2
CC6
—
e
f
g1
g2
h
i
j
k
l
m
dp
7
a1
a2
b
c
d1
d2
—
CC7
e
f
g1
g2
h
i
j
k
l
m
dp
0
Table 3. Connection Scheme for Eight 14-Segment Digits
DIGIT O0
O1
O2
O3
O4
O5
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
0
CCO
—
a
—
b
c
d
—
e
f
g1
g2
h
i
j
k
l
m
dp
1
—
CC1
a
—
b
c
d
—
e
f
g1
g2
h
i
j
k
l
m
dp
2
a
—
CC2
—
b
c
d
—
e
f
g1
g2
h
i
j
k
l
m
dp
3
a
—
—
CC3
b
c
d
—
e
f
g1
g2
h
i
j
k
l
m
dp
4
a
—
b
c
CC4
—
d
—
e
f
g1
g2
h
i
j
k
l
m
dp
5
a
—
b
c
—
CC5
d
—
e
f
g1
g2
h
i
j
k
l
m
dp
6
a
—
b
c
d
—
CC6
—
e
f
g1
g2
h
i
j
k
l
m
dp
7
a
—
b
c
d
—
—
CC7
e
f
g1
g2
h
i
j
k
l
m
dp
Table 4. Connection Scheme for Sixteen 7-Segment Digits
DIGIT* O0
0, 0a CC0
O1
O2
O3
O4
O5
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
—
1a
—
1b
1c
1d
1dp
1e
1f
1g
2a
2b
2c
2d
2e
2f
2g
2dp
1, 1a
—
CC1
1a
—
1b
1c
1d
1dp
1e
1f
1g
2a
2b
2c
2d
2e
2f
2g
2dp
2, 2a
1a
—
CC2
—
1b
1c
1d
1dp
1e
1f
1g
2a
2b
2c
2d
2e
2f
2g
2dp
3, 3a
1a
—
—
CC3
1b
1c
1d
1dp
1e
1f
1g
2a
2b
2c
2d
2e
2f
2g
2dp
4, 4a
1a
—
1b
1c
CC4
—
1d
1dp
1e
1f
1g
2a
2b
2c
2d
2e
2f
2g
2dp
5, 5a
1a
—
1b
1c
—
CC5
1d
1dp
1e
1f
1g
2a
2b
2c
2d
2e
2f
2g
2dp
6, 6a
1a
—
1b
1c
1d
1dp
CC6
—
1e
1f
1g
2a
2b
2c
2d
2e
2f
2g
2dp
7, 7a
1a
—
1b
1c
1d
1dp
—
CC7
1e
1f
1g
2a
2b
2c
2d
2e
2f
2g
2dp
*Each cathode driver output (CC0-CC7) connects to two digit common cathode pins.
Table 5. Serial-Data Format (16 Bits)
D15
R/W
D14
D13
D12
D11
D10
D9
D8
ADDRESS
Reading Device Registers
Any register data within the MAX6954 may be read by
sending a logic high to bit D15. The sequence is:
1) Take CLK low.
8
D7
MSB
D6
D5
D4
D3
D2
DATA
D1
D0
LSB
2) Take CS low. This enables the internal 16-bit shift
register.
3) Clock 16 bits of data into DIN, D15 first to D0 last.
D15 is high, indicating a read command and bits
D14 through D8 contain the address of the register
_______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
DIN
CLK
CLK
CS
CS
DOUT
DOUT
DIN
CLK
MAX6954
MAX6954
DOUT
DIN
CLK
MAX6954
MAX6954
DOUT
MICROCONTROLLER
CS
CS
DIN
Figure 2. MAX6954 Daisy-Chain Connection
tCSW
CS
tCL
tCSS
CLK
tDS
DIN
tCH
tCSH
tCP
tDH
D15
D14
D1
D0
tDO
D15
DOUT
Figure 3. Timing Diagram
to read. Bits D7 to D0 contain dummy data, which is
discarded.
4) Take CS high (while CLK is still high after clocking in
the last data bit), positions D7 through D0 in the shift
register are now loaded with the register data
addressed by bits D15 through D8.
5) Take CLK low.
6) Issue another read or write command (which can be
a no-op), and examine the bit stream at DOUT; the
second 8 bits are the contents of the register
addressed by bits D14 through D8 in step 3.
Digit Type Registers
The MAX6954 uses 32 digit registers to store the characters that the user wishes to display. These digit registers are implemented with two planes, P0 and P1. Each
digit is represented by 2 bytes of memory, 1 byte in
plane P0 and the other in plane P1. The digit registers
are mapped so that a digit’s data can be updated in
plane P0, plane P1, or both planes at the same time
(Table 6).
If the blink function is disabled through the Blink Enable
Bit E (Table 19) 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. 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 20).
The data in the digit registers does not control the digit
segments directly for 14- and 16-segment displays.
Instead, the register data is used to address a character generator that stores the data for the 14- and 16segment fonts (Tables 7 and 8). The lower 7 bits of the
digit data (D6 to D0) select the character from the font.
_______________________________________________________________________________________
9
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
CS
CLK
D15
DIN
D14
D13
D11
D12
D10
D8
D9
D7
D6
D5
D4
D3
D2
D1
D0
D15 = 0
DOUT
Figure 4. Transmission of 16 Bits to the MAX6954
CS
CLK
N-15
DIN
DOUT
BIT
1
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
N-25
N-24
N-23
N-22
N-21
N-20
N-19
N-18
N-17
N-16
BIT
2
N-31
N-30
N-29
N-28
N-27
N-26
N-15
Figure 5. Transmission of More than 16 Bits to the MAX6954
The most significant bit of the register data (D7) controls the DP segment of the digits; it is set to 1 to light
DP, and to zero to leave DP unlit (Table 9).
For 7-segment displays, the digit plane data register
can be used to address a character generator, which
contains the data of a 16-character font containing the
hexadecimal font. The decode mode register can be
used to disable the character generator and allow the
segments to be controlled directly. Table 10 shows the
one-to-one pairing of each data bit to the appropriate
segment line in the digit plane data registers. The hexadecimal font is decoded according to Table 11.
The digit-type register configures the display driver for
various combinations of 14-segment digits, 16-segment
digits, and/or pairs, or 7-segment digits. The function of
this register is to select the appropriate font for each
digit and route the output of the font to the appropriate
MAX6954 driver output pins. The MAX6954 has four
digit drive slots. A slot can be filled with various combinations of monocolor and bicolor 16-segment displays,
14-segment displays, or two 7-segment displays. Each
pair of bits in the register corresponds to one of the four
10
digit drive slots, as shown in Table 12. Each bit also corresponds to one of the eight common-cathode digit
drive outputs, CC0 to CC7. When using bicolor digits,
the anode connections for the two digits within a slot are
always the same. This means that a slot correctly drives
two monocolor or one bicolor 14- or 16-segment digit.
The digit type register can be written, but cannot be
read. Examples of configuration settings required for
some display digit combinations are shown in Table 13.
7-Segment Decode-Mode Register
In 7-segment mode, the hexadecimal font can be disabled (Table 14). The decode-mode register selects
between hexadecimal code or direct control for each of
eight possible pairs of 7-segment digits. Each bit in the
register corresponds to one pair of digits. The digit
pairs are {digit 0, digit 0a} through {digit 7, digit 7a}.
Disabling decode mode allows direct control of the 16
LEDs of a dual 7-segment display. Direct control mode
can also be used to drive a matrix of 128 discrete
LEDs.
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Display Blink Mode
The display blinking facility, when enabled, makes the
driver flip automatically between displaying the digit
register data in planes P0 and P1. If the digit register
data for any digit is different in the two planes, then that
digit appears to flip between two characters. To make a
character appear to blink on or off, write the character
to one plane, and use the blank character (0x20) for the
other plane. Once blinking has been configured, it continues automatically without further intervention.
Blink Speed
The blink speed is determined by the frequency of the
multiplex clock, OSC, and by the setting of the Blink
Rate Selection Bit B (Table 18) in the configuration register. The Blink Rate Selection Bit B sets either fast or
slow blink speed for the whole display.
Initial Power-Up
On initial power-up, all control registers are reset, the
display is blanked, intensities are set to minimum, and
shutdown is enabled (Table 15).
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, select
between global or digit-by-digit control of intensity, and
reset the blink timing (Tables 16–19 and 21–24).
The configuration register contains 7 bits:
• S bit selects shutdown or normal operation
(read/write).
• B bit selects the blink rate (read/write).
• E bit globally enables or disables the blink function
(read/write).
• T bit resets the blink timing (data is not stored—transient bit).
• R bit globally clears the digit data for both planes P0
and P1 for ALL digits (data is not stored—transient
bit).
• I bit selects between global or digit-by-digit control
of intensity (read/write).
• P bit returns the current phase of the blink timing
(read only—a write to this bit is ignored).
Character Generator Font Mapping
The font is composed of 104 characters in ROM. The
lower 7 bits of the 8-bit digit register represent the character selection. The most significant bit, shown as x in
the ROM map of Tables 7 and 8, is 1 to light the DP
segment and zero to leave the DP segment unlit.
The character map follows the standard ASCII font for
96 characters in the x0101000 through x1111111
range. The first 16 characters of the 16-segment ROM
map cover 7-segment displays. These 16 characters
are numeric 0 to 9 and characters A to F (i.e., the hexadecimal set).
Multiplex Clock and Blink Timing
The OSC pin can be fitted with capacitor CSET to GND
to use the internal RC multiplex oscillator, or driven by
an external clock to set the multiplex clock frequency
and blink rate. The multiplex clock frequency determines the frequency that the complete display is updated. With OSC at 4MHz, each display digit is enabled for
200µs.
The internal RC oscillator uses an external resistor,
RSET, and an external capacitor, CSET, to set the oscillator frequency. The suggested values of RSET (56kΩ)
and C SET (22pF) set the oscillator at 4MHz, which
makes the blink frequency 0.5Hz or 1Hz.
The external clock is not required to have a 50:50 duty
cycle, but the minimum time between transitions must
be 50ns or greater and the maximum time between
transitions must be 750ns.
The on-chip oscillator may be accurate enough for
applications using a single device. If an exact blink rate
is required, use an external clock ranging between
1MHz and 8MHz to drive OSC. The OSC inputs of multiple MAX6954s can be tied together to a common external clock to make the devices blink at the same rate.
The relative blink phasing of multiple MAX6954s can be
synchronized by setting the T bit in the control register
for all the devices in quick succession. If the serial interfaces of multiple MAX6954s are daisy-chained by connecting the DOUT of one device to the DIN of the next,
then synchronization is achieved automatically by
updating the configuration register for all devices simultaneously. Figure 6 is the multiplex timing diagram.
OSC_OUT Output
The OSC_OUT output is a buffered copy of either the
internal oscillator clock or the clock driven into the OSC
pin if the external clock has been selected. The feature
is useful if the internal oscillator is used, and the user
wishes to synchronize other MAX6954s to the same
blink frequency. The oscillator is disabled while the
MAX6954 is in shutdown.
______________________________________________________________________________________
11
MAX6954
A logic high selects hexadecimal decoding, while a
logic low bypasses the decoder. When direct control is
selected, the data bits D7 to D0 correspond to the segment lines of the MAX6954. Write x0010000 to blank all
segments in hexadecimal decode mode.
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Scan-Limit Register
GPIO and Key Scanning
The scan-limit register sets how many 14-segment digits or 16-segment digits or pairs of 7-segment digits are
displayed, from 1 to 8. A bicolor digit is connected as
two monocolor digits. The scan register also limits the
number of keys that can be scanned.
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 leading-zero suppression). Table 25 shows the scan-limit register format.
The MAX6954 feature five general-purpose input/output
(GPIO) ports: P0 to P4. These ports can be individually
enabled as logic inputs or open-drain logic outputs.
The GPIO ports are not debounced when configured as
inputs. The ports can be read and the outputs set using
the 4-wire interface.
Some or all of the five ports can be configured to perform key scanning of up to 32 keys. Ports P0 to P4 are
renamed Key_A, Key_B, Key_C, Key_D, and IRQ,
respectively, when used for key scanning. The full keyscanning configuration is shown in Figure 7. Table 30 is
the GPIO data register.
One diode is required per key switch. These diodes
can be common-anode dual diodes in SOT23 packages, such as the BAW56. Sixteen diodes would be
required for the maximum 32-key configuration.
Intensity Registers
Digital control of display brightness is provided and
can be managed in one of two ways: globally or individually. Global control adjusts all digits together.
Individual control adjusts the digits separately.
The default method is global brightness control, which
is selected by clearing the global intensity bit (I data bit
D6) in the configuration register. This brightness setting
applies to all display digits. The pulse-width modulator
is then set by the lower nibble of the global intensity
register, address 0x02. The modulator scales the average segment current in 16 steps from a maximum of
15/16 down to 1/16 of the peak current. The minimum
interdigit blanking time is set to 1/16 of a cycle. When
using bicolor digits, 256 color/brightness combinations
are available.
Individual brightness control is selected by setting the
global intensity bit (I data bit D6) in the configuration
register. The pulse-width modulator is now no longer
set by the lower nibble of the global intensity register,
address 0x02, and the data is ignored. Individual digital
control of display brightness is now provided by a separate pulse-width modulator setting for each digit. Each
digit is controlled by a nibble of one of the four intensity
registers: intensity10, intensity32, intensity54, and intensity76 for all display types, plus intensity10a, intensity32a, intensity54a, and intensity76a for the extra eight
digits possible when 7-segment displays are used. The
data from the relevant register is used for each digit as
it is multiplexed. The modulator scales the average
segment current in 16 steps in exactly the same way as
global intensity adjustment.
Table 26 shows the global intensity register format,
Table 27 shows individual segment intensity registers,
Table 28 is the even individual segment intensity format, and Table 29 is the odd individual segment intensity format.
12
The MAX6954 can only scan the maximum 32 keys if
the scan-limit register is set to scan the maximum eight
digits. If the MAX6954 is driving fewer digits, then a
maximum of (4 x n) switches can be scanned, where n
is the number of digits set in the scan-limit register. For
example, if the MAX6954 is driving four 14-segment
digits cathode drivers O0 to O3 are used. Only 16 keys
can be scanned in this configuration; the switches
shown connected to O4 through O7 are not read.
If the user wishes to scan fewer than 32 keys, then
fewer scan lines can be configured for key scanning.
The unused Key_x ports are released back to their original GPIO functionality. If key scanning is enabled,
regardless of the number of keys being scanned, P4 is
always configured as IRQ (Table 31).
The key-scanning circuit utilizes the LEDs’ commoncathode driver outputs as the key-scan drivers. O0 to
07 go low for nominally 200µs (with OSC = 4MHz) in
turn as the displays are multiplexed. By varying the
oscillator frequency, the debounce time changes,
though key scanning still functions. Key_x inputs have
internal pullup resistors that allow the key condition to
be tested. The Key_x input is low during the appropriate digit multiplex period when the key is pressed. The
timing diagram of Figure 8 shows the normal situation
where all eight LED cathode drivers are used.
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
MAX6954
Table 6. Register Address Map
REGISTER
ADDRESS (COMMAND BYTE)
HEX CODE
D15
D14
D13
D12
D11
D10
D9
D8
No-Op
R/W
0
0
0
0
0
0
0
0x00
Decode Mode
R/W
0
0
0
0
0
0
1
0x01
Global Intensity
R/W
0
0
0
0
0
1
0
0x02
Scan Limit
R/W
0
0
0
0
0
1
1
0x03
Configuration
R/W
0
0
0
0
1
0
0
0x04
GPIO Data
R/W
0
0
0
0
1
0
1
0x05
Port Configuration
R/W
0
0
0
0
1
1
0
0x06
Display Test
R/W
0
0
0
0
1
1
1
0x07
Write KEY_A Mask
Read KEY_A Debounce
R/W
0
0
0
1
0
0
0
0x08
Write KEY_B Mask
Read KEY_B Debounce
R/W
0
0
0
1
0
0
1
0x09
Write KEY_C Mask
Read KEY_C Debounce
R/W
0
0
0
1
0
1
0
0x0A
Write KEY_D Mask
Read KEY_D Debounce
R/W
0
0
0
1
0
1
1
0x0B
Write Digit Type
Read KEY_A Pressed
R/W
0
0
0
1
1
0
0
0x0C
Read KEY_B Pressed*
Read KEY_C Pressed*
Read KEY_D Pressed*
Intensity 10
Intensity 32
Intensity 54
Intensity 76
Intensity 10a (7 Segment Only)
Intensity 32a (7 Segment Only)
Intensity 54a (7 Segment Only)
Intensity 76a (7 Segment Only)
Digit 0 Plane P0
Digit 1 Plane P0
Digit 2 Plane P0
Digit 3 Plane P0
Digit 4 Plane P0
Digit 5 Plane P0
Digit 6 Plane P0
Digit 7 Plane P0
Digit 0a Plane P0 (7 Segment Only)
Digit 1a Plane P0 (7 Segment Only)
Digit 2a Plane P0 (7 Segment Only)
Digit 3a Plane P0 (7 Segment Only)
1
1
1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0x0D
0x0E
0x0F
0x10
0x11
0x12
0x13
0x14
0x15
0x16
0x17
0x20
0x21
0x22
0x23
0x24
0x25
0x26
0x27
0x28
0x29
0x2A
0x2B
*Do NOT write to register.
______________________________________________________________________________________
13
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 6. Register Address Map (continued)
REGISTER
ADDRESS (COMMAND BYTE)
D13
D12
D11
D10
1
0
1
1
1
0
1
1
1
0
1
1
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
0
1
0
0
0
1
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
D15
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
D14
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Write Digit 0 Planes P0 and P1 with Same
Data, Reads as 0x00
R/W
1
1
0
0
Write Digit 1 Planes P0 and P1 with Same
Data, Reads as 0x00
R/W
1
1
0
Write Digit 2 Planes P0 and P1 with Same
Data, Reads as 0x00
R/W
1
1
Write Digit 3 Planes P0 and P1 with Same
Data, Reads as 0x00
R/W
1
Write Digit 4 Planes P0 and P1 with Same
Data, Reads as 0x00
R/W
Write Digit 5 Planes P0 and P1 with Same
Data, Reads as 0x00
HEX CODE
D9
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
D8
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
0
0
0x60
0
0
0
1
0x61
0
0
0
1
0
0x62
1
0
0
0
1
1
0x63
1
1
0
0
1
0
0
0x64
R/W
1
1
0
0
1
0
1
0x65
Write Digit 6 Planes P0 and P1 with Same
Data, Reads as 0x00
R/W
1
1
0
0
1
1
0
0x66
Write Digit 7 Planes P0 and P1 with Same
Data, Reads as 0x00
R/W
1
1
0
0
1
1
1
0x67
Write Digit 0a Planes P0 and P1 with Same
Data (7 Segment Only), Reads as 0x00
R/W
1
1
0
1
0
0
0
0x68
Write Digit 1a Planes P0 and P1 with Same
Data (7 Segment Only), Reads as 0x00
R/W
1
1
0
1
0
0
1
0x69
Digit 4a Plane P0 (7 Segment Only)
Digit 5a Plane P0 (7 Segment Only)
Digit 6a Plane P0 (7 Segment Only)
Digit 7a Plane P0 (7 Segment Only)
Digit 0 Plane P1
Digit 1 Plane P1
Digit 2 Plane P1
Digit 3 Plane P1
Digit 4 Plane P1
Digit 5 Plane P1
Digit 6 Plane P1
Digit 7 Plane P1
Digit 0a Plane P1 (7 Segment Only)
Digit 1a Plane P1 (7 Segment Only)
Digit 2a Plane P1 (7 Segment Only)
Digit 3a Plane P1 (7 Segment Only)
Digit 4a Plane P1 (7 Segment Only)
Digit 5a Plane P1 (7 Segment Only)
Digit 6a Plane P1 (7 Segment Only)
Digit 7a Plane P1 (7 Segment Only)
14
______________________________________________________________________________________
0x2C
0x2D
0x2E
0x2F
0x40
0x41
0x42
0x43
0x44
0x45
0x46
0x47
0x48
0x49
0x4A
0x4B
0x4C
0x4D
0x4E
0x4F
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
MAX6954
Table 6. Register Address Map (continued)
REGISTER
ADDRESS (COMMAND BYTE)
HEX CODE
D15
D14
D13
D12
D11
D10
D9
D8
Write Digit 2a Planes P0 and P1 with Same
Data (7 Segment Only), Reads as 0x00
R/W
1
1
0
1
0
1
0
0x6A
Write Digit 3a Planes P0 and P1 with Same
Data (7 Segment Only), Reads as 0x00
R/W
1
1
0
1
0
1
1
0x6B
Write Digit 4a Planes P0 and P1 with Same
Data (7 Segment Only), Reads as 0x00
R/W
1
1
0
1
1
0
0
0x6C
Write Digit 5a Planes P0 and P1 with Same
Data (7 Segment Only), Reads as 0x00
R/W
1
1
0
1
1
0
1
0x6D
Write Digit 6a Planes P0 and P1 with Same
Data (7 Segment Only), Reads as 0x00
R/W
1
1
0
1
1
1
0
0x6E
Write Digit 7a Planes P0 and P1 with Same
Data (7 Segment Only), Reads as 0x00
R/W
1
1
0
1
1
1
1
0x6F
Note: Unused register bits read as zero.
The timing in Figure 8 loops over time, with 32 keys
experiencing a full key-scanning debounce over typically 25.6ms. Four keys are sampled every 1.6ms, or
every multiplex cycle. If at least one key that was not
previously pressed is found to have been pressed during both sampling periods, then that key press is
debounced, and an interrupt is issued. The key-scan
circuit detects any combination of keys being pressed
during each debounce cycle (n-key rollover).
Port Configuration Register
The port configuration register selects how the five port
pins are used. The port configuration register format is
described in Table 32.
Key Mask Registers
The Key_A Mask, Key_B Mask, Key_C Mask, and
Key_D Mask write-only registers (Table 33) configure
the key-scanning circuit to cause an interrupt only when
selected (masked) keys have been debounced. Each
bit in the register corresponds to one key switch. The bit
is clear to disable interrupt for the switch, and set to
enable interrupt. Keys are always scanned (if enabled
through the port configuration register), regardless of
the setting of these interrupt bits, and the key status is
stored in the appropriate Key_x pressed register.
Key Debounced Registers
The Key_A debounced, Key_B debounced, Key_C
debounced, and Key_D debounced read-only registers
(Table 34) show which keys have been detected as
debounced by the key-scanning circuit.
Each bit in the register corresponds to one key switch.
The bit is set if the switch has been correctly
debounced since the register was read last. Reading a
debounced register clears that register (after the data
has been read) so that future keys pressed can be
identified. If the debounced registers are not read, the
key-scan data accumulates. However, as there is no
FIFO in the MAX6954, the user is not able to determine
key order, or whether a key has been pressed more
than once, unless the debounced key status registers
are read after each interrupt, and before the next keyscan cycle.
Reading any of the four debounced registers clears the
IRQ output. If a key is pressed and held down, the key is
reported as debounced (and IRQ issued) only once.
The key must be detected as released by the key-scanning circuit, before it debounces again. If the
debounced registers are being read in response to the
IRQ being asserted, then the user should generally read
all four registers to ensure that all the keys that were
detected by the key-scanning circuit are discovered.
Key Pressed Registers
The Key_A pressed, Key_B pressed, Key_C pressed,
and Key_D pressed read-only registers (Table 35)
show which keys have been detected as pressed by
the key-scanning circuit during the last test.
Each bit in the register corresponds to one key switch.
The bit is set if the switch has been detected as
pressed by the key-scanning circuit during the last test.
______________________________________________________________________________________
15
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
START OF
NEXT CYCLE
ONE COMPLETE 1.6ms MULTIPLEX CYCLE AROUND 8 DIGITS
200μs
DIGIT 0
DIGIT 1
DIGIT 2
DIGIT 3
DIGIT 4
DIGIT 5
DIGIT 6
DIGIT 7
DIGIT 0 CATHODE
DRIVER INTENSITY
SETTINGS
DIGIT 0's 200μs MULTIPLEX TIMESLOT
1/16TH
HIGH-Z
(MIN ON)
HIGH-Z
2/16TH
LOW
HIGH-Z
3/16TH
LOW
HIGH-Z
4/16TH
LOW
HIGH-Z
5/16TH
LOW
HIGH-Z
6/16TH
LOW
HIGH-Z
7/16TH
LOW
HIGH-Z
8/16TH
LOW
HIGH-Z
9/16TH
LOW
HIGH-Z
10/16TH
LOW
HIGH-Z
11/16TH
LOW
HIGH-Z
12/16TH
LOW
HIGH-Z
13/16TH
LOW
HIGH-Z
14/16TH
LOW
HIGH-Z
15/16TH
LOW
15/16TH
(MAX ON)
ANODE (LIT)
HIGH-Z
LOW
CURRENT SOURCE ENABLED
HIGH-Z
MINIMUM 12.5μs INTERDIGIT BLANKING INTERVAL
HIGH-Z
ANODE (UNLIT)
HIGH-Z
Figure 6. Multiplex Timing Diagram (OSC = 4MHz)
16
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
MAX6954
LED OUTPUT O0
SW A0
SW B0
SW C0
SW D0
SW A1
SW B1
SW C1
SW D1
SW A2
SW B2
SW C2
SW D2
SW A3
SW B3
SW C3
SW D3
SW A4
SW B4
SW C4
SW D4
SW A5
SW B5
SW C5
SW D5
SW A6
SW B6
SW C6
SW D6
SW A7
SW B7
SW C7
SW D7
LED OUTPUT O1
LED OUTPUT O2
LED OUTPUT O3
LED OUTPUT O4
LED OUTPUT O5
LED OUTPUT O6
LED OUTPUT O7
VCC
P0
P1
P2
P3
MICROCONTROLLER INTERRUPT
P4
Figure 7. Key-Scanning Configuration
THE FIRST HALF OF A 25.6ms KEY-SCAN CYCLE
1.6ms MULTIPLEX CYCLE 1
1.6ms MULTIPLEX CYCLE 2
THE SECOND HALF OF A 25.6ms KEY-SCAN CYCLE
1.6ms MULTIPLEX CYCLE 1
1.6ms MULTIPLEX CYCLE 8
1.6ms MULTIPLEX CYCLE 8
12.5μs TO 187.5μs DIGIT PERIOD
LED OUTPUT O0
LED OUTPUT O1
LED OUTPUT O2
LED OUTPUT O3
LED OUTPUT O4
LED OUTPUT O5
LED OUTPUT O6
LED OUTPUT O7
A
B
C
D
E
A
FIRST TEST OF KEY SWITCHES
SECOND TEST OF KEY SWITCHES
INTERRUPT ASSERTED IF REQUIRED
DEBOUNCE REGISTER UPDATED
START OF NEXT KEY-SCAN CYCLE
Figure 8. Key-Scan Timing Diagram
______________________________________________________________________________________
17
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
The bit is cleared if the switch has not been detected
as pressed by the key-scanning circuit during the last
test. Reading a pressed register does not clear that
register or clear the IRQ output.
Display Test Register
The display test register (Table 36) operates in two
modes: normal and display test. Display test mode
turns all LEDs on (including DPs) by overriding, but not
altering, all controls and digit registers (including the
shutdown register), except for the digit-type register
and the GPIO configuration register. The duty cycle,
while in display test mode, is 7/16 (see the Choosing
Supply Voltage to Minimize Power Dissipation section).
Selecting External Components RSET and
CSET to Set Oscillator Frequency and
Peak Segment Current
The RC oscillator uses an external resistor, RSET, and
an external capacitor, CSET, to set the 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 4MHz, which
makes the blink frequencies selectable between 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 = KL / RSET mA
fOSC = KF / (RSET x CSET) MHz
where:
KL = 2240
KF = 5376
RSET = external resistor in kΩ
CSET = external capacitor in pF
CSTRAY = stray capacitance from OSC pin to GND in
pF, typically 2pF
The recommended value of RSET is 56kΩ and the recommended value of CSET is 22pF.
The recommended value or R SET is the minimum
allowed value, since it sets the display driver to the
maximum allowed peak 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 RSET includes not only the actual
external capacitor used, but also the stray capacitance
from OSC to GND. This capacitance is usually in the
1pF to 5pF range, depending on the layout used.
18
Applications Information
Driving Bicolor LEDs
Bicolor digits group a red and a green die together for
each display element, so that the element can be lit red
or green (or orange), depending on which die (or both)
is lit. The MAX6954 allows each segment’s current to
be set individually from the 1/16th (minimum current
and LED intensity) to 15/16th (maximum current and
LED intensity), as well as off (zero current). Thus, a
bicolor (red-green) segment pair can be set to 256
color/intensity combinations.
Choosing Supply Voltage to Minimize
Power Dissipation
The MAX6954 drives a peak current of 40mA into LEDs
with a 2.2V 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 2.2V) = 0.8V. 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 2.2V, the
supply voltage must be raised accordingly to ensure
that the driver always has at least 0.8V of headroom.
The voltage drop across the drivers with a nominal 5V
supply (5.0V - 2.2V) = 2.8V is nearly 3 times the drop
across the drivers with a nominal 3.3V supply (3.3V 2.2V) = 1.1V. In most systems, consumption is an
important design criterion, and the MAX6954 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
MAX6954 is not exceeded. This can be achieved by
inserting a series resistor in the supply to the MAX6954,
ensuring that the supply decoupling capacitors are still
on the MAX6954 side of the resistor. For example, consider the requirement that the minimum supply voltage
to a MAX6954 must be 3.0V, and the input supply
range is 5V ±5%. Maximum supply current is 35mA +
(40mA x 17) = 715mA. Minimum input supply voltage is
4.75V. Maximum series resistor value is (4.75V 3.0V)/0.715A = 2.44Ω. We choose 2.2Ω ±5%. Worstcase resistor dissipation is at maximum toleranced
resistance, i.e., (0.715A) 2 x (2.2Ω x 1.05) = 1.18W. The
maximum MAX6954 supply voltage is at maximum
input supply voltage and minimum toleranced resistance, i.e., 5.25V - (0.715A x 2.2Ω x 0.95) = 3.76V.
Low-Voltage Operation
The MAX6954 works 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
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Computing Power Dissipation
The upper limit for power dissipation (P D ) for the
MAX6954 is determined from the following equation:
PD = (V+ x 35mA) + (V+ - VLED) (DUTY x ISEG x N)
where:
V+ = supply voltage
DUTY = duty cycle set by intensity register
N = number of segments driven (worst case is 17)
VLED = LED forward voltage at ISEG
ISEG = segment current set by RSET
PD = Power dissipation, in mW if currents are in mA
Dissipation example:
ISEG = 30mA, N = 17, DUTY = 15/16,
VLED = 2.4V at 30mA, V+ = 3.6V
PD = 3.6V (35mA) + (3.6V - 2.4V)(15/16 x
30mA x 17) = 0.700W
Thus, for a 36-pin SSOP package (TJA = 1 / 0.0118 =
+85°C/W from Operating Ratings), the maximum
allowed ambient temperature TA is given by:
TJ(MAX) = TA + (PD x TJA) = +150°C
= TA + (0.700 x +85°C/W)
So TA = +90.5°C. Thus, the part can be operated safely
at a maximum package temperature of +85°C.
Power Supplies
The MAX6954 operates from a single 2.7V to 5.5V
power supply. Bypass the power supply to GND with a
0.1µF capacitor as close to the device as possible. Add
a 47µF capacitor if the MAX6954 is not close to the
board's input bulk decoupling capacitor.
Terminating the Serial Interface
The MAX6954 uses fixed voltage thresholds of 0.6V
and 1.8V for the 4-wire interface inputs. These fixed
thresholds allow the MAX6954 to be controlled by a
host operating from a lower supply voltage than the
MAX6954; for example, 2.5V. The fixed thresholds also
reduce the logic input noise margin when operating the
MAX6954 from a higher supply voltage, such as 5V. At
higher supply voltages, it may be necessary to fit termination components to the CLK, DIN, and CS inputs to
avoid signal reflections that the MAX6954 could
respond to as multiple transitions. Suitable termination
components can be either a 33pF capacitor or 4.7kΩ
resistor fitted from each of the CLK, DIN, and CS inputs
to GND.
______________________________________________________________________________________
19
MAX6954
peak current ISEG, plus the 0.8V headroom required by
the driver output stages. The MAX6954 correctly regulates ISEG with a supply voltage above this minimum
voltage. If the supply drops below this minimum voltage, the driver output stages may brown out, and be
unable to regulate the current correctly. As the supply
voltage drops further, the LED segment drive current
becomes effectively limited by the output driver's onresistance, and the LED drive current drops. The characteristics of each individual LED in a display digit are
well matched, so the result is that the display intensity
dims uniformly as supply voltage drops out of regulation and beyond.
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 7. 16-Segment Display Font Map
MSB
LSB
x000
x001
x010
x011
x100
x101
x110
x111
Table 8. 14-Segment Display Font Map
MSB
LSB
0000
0000
0001
0001
0010
0010
0011
0011
0100
0100
0101
0101
0110
0110
0111
0111
1000
1000
1001
1001
1010
1010
1011
1011
1100
1100
1101
1101
1110
1110
1111
1111
x000
x001
x010
x011
x100
x101
x110
x111
.
20
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
ADDRESS
CODE
(HEX)
MODE
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
14-segment or 16-segment mode, writing digit data
to use font map data with decimal place unlit
0x20 to 0x2F
0x40 to 0x4F
0x60 to 0x6F
0
Bits D6 to D0 select font characters 0 to 127
14-segment or 16-segment mode, writing digit data
to use font map data with decimal place lit
0x20 to 0x2F
0x40 to 0x4F
0x60 to 0x6F
1
Bits D6 to D0 select font characters 0 to 127
7-segment decode mode, DP unlit
0x20 to 0x2F
0x40 to 0x4F
0x60 to 0x6F
0
0
0
0
D3 to D0
7-segment decode mode, DP lit
0x20 to 0x2F
0x40 to 0x4F
0x60 to 0x6F
1
0
0
0
D3 to D0
7-segment no-decode mode
0x20 to 0x2F
0x40 to 0x4F
0x60 to 0x6F
Direct control of 8 segments
Table 10. Segment Decoding for 7-Segment Displays
MODE
Segment Line
ADDRESS CODE
(HEX)
0x20 to 0x2F
0x40 to 0x4F
0x60 to 0x6F
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
dp
a
b
c
d
e
f
g
______________________________________________________________________________________
21
MAX6954
Table 9. Digit Plane Data Register Format
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 11. 7-Segment Segment Mapping Decoder for Hexadecimal Font
REGISTER
DATA
7-SEGMENT
CHARACTER
D7*
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
D6, D5,
D4
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
ON SEGMENTS = 1
D3
D2
D1
D0
DP*
A
B
C
D
E
F
G
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
1
0
1
1
0
1
1
1
1
1
1
0
1
0
1
1
1
1
1
1
1
0
0
1
1
1
1
0
0
1
0
0
1
1
0
1
1
1
1
1
1
1
1
1
0
1
0
0
1
0
1
1
0
1
1
0
1
1
0
1
1
1
1
0
1
0
1
0
0
0
1
0
1
0
1
1
1
1
1
1
1
0
0
0
1
1
1
0
1
1
1
1
1
0
1
1
0
0
1
1
1
1
1
0
1
1
1
1
0
1
1
1
*The decimal point is set by bit D7 = 1.
Table 12. Digit-Type Register
DIGIT-TYPE
REGISTER
Output Drive Line
Slot Identification
22
ADDRESS
CODE (HEX)
0x0C
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
CC7
CC6
CC5
CC4
CC3
CC2
CC1
CC0
Slot 4
Slot 3
Slot 2
______________________________________________________________________________________
Slot 1
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
REGISTER DATA
DIGIT-TYPE
REGISTER SETTING
ADDRESS
CODE (HEX)
D7
D6
D5
D4
D3
D2
D1
D0
Digits 7 to 0 are 16-segment or 7segment digits.
0x0C
0
0
0
0
0
0
0
0
Digit 0 is a 14-segment digit,
digits 7 to 1 are 16-segment or 7segment digits.
0x0C
0
0
0
0
0
0
0
1
Digits 2 to 0 are 14-segment
digits, digits 7 to 3 are 16segment or 7-segment digits.
0x0C
0
0
0
0
0
1
1
1
Digits 7 to 0 are 14-segment
digits.
0x0C
1
1
1
1
1
1
1
1
Table 14. Decode-Mode Register Examples
DECODE
MODE
No decode for digit pairs 7 to 0.
Hexadecimal decode for digit pair 0,
no decode for digit pairs 7 to 1.
Hexadecimal decode for digit pairs 2 to 0,
no decode for digit pairs 7 to 3.
Hexadecimal decode for digit pairs 7 to 0.
ADDRESS
CODE
(HEX)
D7
D6
D5
D4
D3
D2
D1
D0
0x01
0
0
0
0
0
0
0
0
0x00
0x01
0
0
0
0
0
0
0
1
0x01
0x01
0
0
0
0
0
1
1
1
0x07
0x01
1
1
1
1
1
1
1
1
0xFF
REGISTER DATA
HEX
CODE
______________________________________________________________________________________
23
MAX6954
Table 13. Example Configurations for Display Digit Combinations
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 15. Initial Power-Up Register Status
REGISTER
Decode Mode
Global Intensity
Scan Limit
Control Register
GPIO Data
Port Configuration
Display Test
Key_A Mask
Key_B Mask
Key_C Mask
Key_D Mask
Digit Type
Intensity10
Intensity32
Intensity54
Intensity76
Intensity10a
Intensity32a
Intensity54a
Intensity76a
Digit 0
Digit 1
Digit 2
Digit 3
Digit 4
Digit 5
Digit 6
Digit 7
Digit 0a
Digit 1a
Digit 2a
Digit 3a
Digit 4a
Digit 5a
Digit 6a
Digit 7a
Key_A Debounced
Key_B Debounced
Key_C Debounced
Key_D Debounced
Key_A Pressed
Key_B Pressed
Key_C Pressed
Key_D Pressed
24
POWER-UP
CONDITION
Decode mode enabled
1/16 (min on)
Display 8 digits: 0, 1, 2, 3, 4, 5, 6, 7
Shutdown enabled, blink speed is
slow, blink disabled
Outputs are low
No key scanning, P0 to P4 are all
inputs
Normal operation
None of the keys cause interrupt
None of the keys cause interrupt
None of the keys cause interrupt
None of the keys cause interrupt
All are 16 segment or 7 segment
1/16 (min on)
1/16 (min on)
1/16 (min on)
1/16 (min on)
1/16 (min on)
1/16 (min on)
1/16 (min on)
1/16 (min on)
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
Blank digit, both planes
No key presses have been detected
No key presses have been detected
No key presses have been detected
No key presses have been detected
Keys are not pressed
Keys are not pressed
Keys are not pressed
Keys are not pressed
ADDRESS
CODE
(HEX)
0x01
0x02
0x03
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
1
X
X
1
X
X
1
X
X
1
X
X
1
0
X
1
0
1
1
0
1
1
0
1
0x04
0
0
X
X
0
0
0
0
0x05
X
X
X
0
0
0
0
0
0x06
0
0
0
1
1
1
1
1
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x10
0x11
0x12
0x13
0x14
0x15
0x16
0x17
0x60
0x61
0x62
0x63
0x64
0x65
0x66
0x67
0x68
0x69
0x6A
0x6B
0x6C
0x6D
0x6E
0x6F
0x88
0x89
0x8A
0x8B
0x8C
0x8D
0x8E
0x8F
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
MODE
Configuration
Register
Table 17. Shutdown Control (S Data Bit DO)
Format
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
REGISTER DATA
MODE
P
I
R
T
E
B
X
D7
D6
D5
D4
D3
D2
D1
D0
Shutdown
P
I
R
T
E
B
X
0
Normal
Operation
P
I
R
T
E
B
X
1
S
Table 18. Blink Rate Selection (B Data Bit D2) Format
REGISTER DATA
MODE
D7
D6
D5
D4
D3
D2
D1
D0
Slow blinking. Segments blink on for 1s, off for 1s with fOSC = 4MHz.
P
I
R
T
E
0
X
S
Fast blinking. Segments blink on for 0.5s, off for 0.5s with fOSC = 4MHz.
P
I
R
T
E
1
X
S
Table 19. Global Blink Enable/Disable (E Data Bit D3) Format
MODE
D7
P
P
Blink function is disabled.
Blink function is enabled.
D6
I
I
D5
R
R
REGISTER DATA
D4
D3
T
0
T
1
D2
B
B
D1
X
X
D0
S
S
Table 20. Digit Register Mapping with Blink Globally Enabled
SEGMENT’S BIT SETTING
IN PLANE P1
SEGMENT’S BIT SETTING
IN PLANE P0
SEGMENT
BEHAVIOR
0
0
Segment off.
0
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.
Table 21. Global Blink Timing Synchronization (T Data Bit D4) Format
MODE
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
Blink timing counters are unaffected.
P
I
R
0
E
B
X
S
Blink timing counters are reset on the rising edge of CS.
P
I
R
1
E
B
X
S
Table 22. Global Clear Digit Data (R Data Bit D5) Format
MODE
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
Digit data for both planes P0 and P1 are unaffected.
P
I
0
T
E
B
X
S
Digit data for both planes P0 and P1 are cleared on the rising edge of CS.
P
I
1
T
E
B
X
S
______________________________________________________________________________________
25
MAX6954
Table 16. Configuration Register Format
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 23. Global Intensity (I Data Bit D6) Format
REGISTER DATA
MODE
D7
D6
D5
D4
D3
D2
D1
D0
Intensity for all digits is controlled by one setting in the global intensity register.
P
0
R
T
E
B
X
S
Intensity for digits is controlled by the individual settings in the intensity10 and
intensity76 registers.
P
1
R
T
E
B
X
S
Table 24. Blink Phase Readback (P Data Bit D7) Format
MODE
D7
0
1
P1 Blink Phase
P0 Blink Phase
D6
I
I
REGISTER DATA
D4
D3
T
E
T
E
D5
R
R
D2
B
B
D1
X
X
D0
S
S
Table 25. Scan-Limit Register Format
SCAN
LIMIT
ADDRESS CODE
(HEX)
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
HEX
CODE
Display Digit 0 only
0x03
X
X
X
X
X
0
0
0
0x00
Display Digits 0 and 1
0x03
X
X
X
X
X
0
0
1
0x01
Display Digits 0 1 2
0x03
X
X
X
X
X
0
1
0
0x02
Display Digits 0 1 2 3
0x03
X
X
X
X
X
0
1
1
0x03
Display Digits 0 1 2 3 4
0x03
X
X
X
X
X
1
0
0
0x04
Display Digits 0 1 2 3 4 5
0x03
X
X
X
X
X
1
0
1
0x05
Display Digits 0 1 2 3 4 5 6
0x03
X
X
X
X
X
1
1
0
0x06
Display Digits 0 1 2 3 4 5 6 7
0x03
X
X
X
X
X
1
1
1
0x07
Table 26. Global Intensity Register Format
DUTY
CYCLE
TYPICAL
SEGMENT
CURRENT (mA)
ADDRESS
CODE (HEX)
1/16 (min on)
2.5
0x02
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
X
X
X
X
0
0
0
0
HEX
CODE
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
26
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
MAX6954
Table 27. Individual Segment Intensity Registers
REGISTER
FUNCTION
ADDRESS
CODE (HEX)
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
Intensity10 Register
0x10
Digit 1
Digit 0
Intensity32 Register
0x11
Digit 3
Digit 2
Intensity54 Register
0x12
Digit 5
Digit 4
Intensity76 Register
0x13
Digit 7
Digit 6
Intensity10a Register
0x14
Digit 1a (7 segment only)
Digit 0a (7 segment only)
Intensity32a Register
0x15
Digit 3a (7 segment only)
Digit 2a (7 segment only)
Intensity54a Register
0x16
Digit 5a (7 segment only)
Digit 4a (7 segment only)
Intensity76a Register
0x17
Digit 7a (7 segment only)
Digit 6a (7 segment only)
Table 28. Even Individual Segment Intensity Format
DUTY
CYCLE
TYPICAL
SEGMENT
CURRENT (mA)
ADDRESS
CODE
(HEX)
1/16 (min on)
2.5
2/16
5
3/16
4/16
5/16
REGISTER DATA
D7
D6
D5
D3
D2
D1
D0
0x10 to 0x17
0
0
0
0
0xX0
0x10 to 0x17
0
0
0
1
0xX1
7.5
0x10 to 0x17
0
0
1
0
0xX2
10
0x10 to 0x17
0
0
1
1
0xX3
12.5
0x10 to 0x17
0
1
0
0
0xX4
6/16
15
0x10 to 0x17
0
1
0
1
0xX5
7/16
17.5
0x10 to 0x17
0
1
1
0
0xX6
8/16
20
0x10 to 0x17
0
1
1
1
0xX7
0xX8
See Table 29.
D4
HEX
CODE
9/16
22.5
0x10 to 0x17
1
0
0
0
10/16
25
0x10 to 0x17
1
0
0
1
0xX9
11/16
27.5
0x10 to 0x17
1
0
1
0
0xXA
12/16
30
0x10 to 0x17
1
0
1
1
0xXB
13/16
32.5
0x10 to 0x17
1
1
0
0
0xXC
14/16
35
0x10 to 0x17
1
1
0
1
0xXD
15/16
37.5
0x10 to 0x17
1
1
1
0
0xXE
15/16 (max on)
37.5
0x10 to 0x17
1
1
1
1
0xXF
______________________________________________________________________________________
27
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 29. Odd Individual Segment Intensity Format
DUTY
CYCLE
TYPICAL
SEGMENT
CURRENT (mA)
ADDRESS
CODE
(HEX)
D7
D6
D5
D4
1/16 (min on)
2.5
0x10 to 0x17
0
0
0
0
0x0X
REGISTER DATA
D3
D2
D1
D0
HEX
CODE
2/16
5
0x10 to 0x17
0
0
0
1
0x1X
3/16
7.5
0x10 to 0x17
0
0
1
0
0x2X
4/16
10
0x10 to 0x17
0
0
1
1
0x3X
5/16
12.5
0x10 to 0x17
0
1
0
0
0x4X
6/16
15
0x10 to 0x17
0
1
0
1
0x5X
7/16
17.5
0x10 to 0x17
0
1
1
0
0x6X
8/16
20
0x10 to 0x17
0
1
1
1
9/16
22.5
0x10 to 0x17
1
0
0
0
10/16
25
0x10 to 0x17
1
0
0
1
0x9X
11/16
27.5
0x10 to 0x17
1
0
1
0
0xAX
12/16
30
0x10 to 0x17
1
0
1
1
0xBX
13/16
32.5
0x10 to 0x17
1
1
0
0
0xCX
14/16
35
0x10 to 0x17
1
1
0
1
0xDX
15/16
37.5
0x10 to 0x17
1
1
1
0
0xEX
15/16 (max on)
37.5
0x10 to 0x17
1
1
1
1
0xFX
0x7X
See Table 28.
0x8X
Table 30. GPIO Data Register
REGISTER DATA
D4
D3
D2
D1
D0
X
P4
P3
P2
P1
P0
0
P4 or IRQ status
P3
P2
P1
P0
MODE
ADDRESS
CODE (HEX)
D7
D6
D5
Write GPIO Data
0x05
X
X
Read GPIO Data
0x85
0
0
Table 31. Port Scanning Function Allocation
28
KEYS
SCANNED
None
PORTS
AVAILABLE
5 pins
P0
P1
P2
P3
P4
GPIO
GPIO
GPIO
GPIO
GPIO
1 to 8
3 pins
Key_A
GPIO
GPIO
GPIO
IRQ
9 to 16
2 pins
Key_A
Key_B
GPIO
GPIO
IRQ
17 to 24
1 pin
Key_A
Key_B
Key_C
GPIO
IRQ
25 to 36
None
Key_A
Key_B
Key_C
Key_D
IRQ
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
MODE
ADDRESS
CODE (HEX)
D7
D6
D5
GPIO
0x06
Set number of keys scanned
Configuration
Register
PORT ALLOCATION OPTIONS
0 Keys Scanned
0x06
0
0
0
8 Keys Scanned
0x06
0
0
1
16 Keys Scanned
0x06
0
1
0
24 Keys Scanned
0x06
0
1
1
32 Keys Scanned
0x06
1
X
X
EXAMPLE PORT CONFIGURATION SETTINGS
No Keys
Scanned, P4 and
0x06
0
0
0
P2 Are Outputs,
Others Are Inputs
8 Keys Scanned,
P3 and P1 Are
0x06
0
0
1
Outputs, P2 Is an
Input
32 Keys
Scanned, No
0x06
1
X
X
GPIO Ports
REGISTER DATA
D4
D3
D2
D1
D0
Set port direction for ports P0 to P4:
0 = output, 1 = input
P4
IRQ
IRQ
IRQ
IRQ
P3
P3
P3
P3
Key_D
P2
P2
P2
Key_C
Key_C
P1
P1
Key_B
Key_B
Key_B
P0
Key_A
Key_A
Key_A
Key_A
0
1
0
1
1
X
0
1
0
X
X
X
X
X
X
Table 33. Key Mask Register Format
REGISTER DATA
WITH APPROPRIATE SWITCH NAMED BELOW
KEY
MASK
REGISTER
ADDRESS
CODE
(HEX
D7
D6
D5
D4
D3
D2
D1
D0
Key_A Mask
Register
0x08
SW_A7
SW_A6
SW_A5
SW_A4
SW_A3
SW_A2
SW_A1
SW_A0
Key_B Mask
Register
0x09
SW_B7
SW_B6
SW_B5
SW_B4
SW_B3
SW_B2
SW_B1
SW_B0
Key_C Mask
Register
0x0A
SW_C7
SW_C6
SW_C5
SW_C4
SW_C3
SW_C2
SW_C1
SW_C0
Key_D Mask
Register
0x0B
SW_ D7
SW_D6
SW_D5
SW_D4
SW_D3
SW_D2
SW_D1
SW_D0
______________________________________________________________________________________
29
MAX6954
Table 32. Port Configuration Register Format
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 34. Key Debounced Register Format
KEY
DEBOUNCED
REGISTER
ADDRESS
CODE
(HEX)
D7
D6
D5
D4
D3
D2
D1
D0
Key_A
Debounced
Register
0x88
SW_A7
SW_A6
SW_A5
SW_A4
SW_A3
SW_A2
SW_A1
SW_A0
Key_B
Debounced
Register
0x89
SW_B7
SW_B6
SW_B5
SW_B4
SW_B3
SW_B2
SW_B1
SW_B0
Key_C
Debounced
Register
0x8A
SW_C7
SW_C6
SW_C5
SW_C4
SW_C3
SW_C2
SW_C1
SW_C0
Key_D
Debounced
Register
0x8B
SW_D7
SW_D6
SW_D5
SW_D4
SW_D3
SW_D2
SW_D1
SW_D0
REGISTER DATA
Table 35. Key Pressed Register Format
KEY
PRESSED
REGISTER
ADDRESS
CODE
(HEX
D7
D6
D5
D4
D3
D2
D1
D0
Key_A
Pressed
Register
0x8C
SW_A7
SW_A6
SW_A5
SW_A4
SW_A3
SW_A2
SW_A1
SW_A0
Key_B
Pressed
Register
0x8D
SW_B7
SW_B6
SW_B5
SW_B4
SW_B3
SW_B2
SW_B1
SW_B0
Key_C
Pressed
Register
0x8E
SW_C7
SW_C6
SW_C5
SW_C4
SW_C3
SW_C2
SW_C1
SW_C0
Key_D
Pressed
Register
0x8F
SW_D7
SW_D6
SW_D5
SW_D4
SW_D3
SW_D2
SW_D1
SW_D0
D1
D0
REGISTER DATA
Table 36. Display Test Register
MODE
ADDRESS
CODE
(HEX)
REGISTER DATA
D7
D6
D5
D4
D3
D2
Normal Operation
0x07
X
X
X
X
X
X
X
0
Display Test
0x07
X
X
X
X
X
X
X
1
30
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
CC0: 16-seg monocolor
CC0: (2) 7-seg monocolor*
or 7-seg bicolor
CC1: 14-seg monocolor
CC0: 14-seg monocolor
CC1: (2) 7-seg monocolor*
or 7-seg bicolor
CC0 and CC1: (2) 14-seg
monocolor or 14-seg
bicolor
—
CC0
CC0
CC0
CC0
—
CC0
—
—
CC0
—
CC1
CC1
CC1
—
—
CC1
—
CC1
CC1
CC1
02
a1
a1
1a
a1
a1
1a
a
a
a1
1a
a
03
a2
a2
—
a2
a2
—
—
—
a2
—
—
04
b
b
1b
b
b
1b
b
b
b
1b
b
05
c
c
1c
c
c
1c
c
c
c
1c
c
06
d1
d1
1d
d1
d1
1d
d
d
d1
1d
d
07
d2
d2
1dp
d2
d2
1dp
—
—
d2
1dp
—
08
e
e
1e
e
e
1e
e
e
e
1e
e
09
f
f
1f
f
f
1f
f
f
f
1f
f
010
g1
g1
1g
g1
g1
1g
g1
g1
g1
1g
g1
011
g2
g2
2a
g2
g2
2a
g2
g2
g2
2a
g2
012
h
h
2b
h
h
2b
h
h
h
2b
h
013
i
i
2c
i
i
2c
i
i
i
2c
i
014
j
j
2d
j
j
2d
j
j
j
2d
j
015
k
k
2e
k
k
2e
k
k
k
2e
k
016
l
l
2f
l
l
2f
l
l
l
2f
l
017
m
m
2g
m
m
2g
m
m
m
2g
m
018
dp
dp
2dp
dp
dp
2dp
dp
dp
dp
2dp
dp
ADDRESS
CODE (HEX)
0x0C
D7
REGISTER DATA
CC1: 16-seg monocolor
CC0 and CC1:
(1)16-seg bicolor
CC0
01
CC0 and CC1:
(2) 7-seg bicolor
or (4) 7-seg monocolor
or (1) 7-seg bicolor
and (2) 7-seg monocolor*
CC0: 16-seg monocolor
00
CC1: 16-seg monocolor
CONFIGURATION
CHOICE
Common-Cathode
Drive: Digit Type
See Table 40.
D6
D5
See Table 39.
D4
D3
See Table 38.
D2
D1
D0
0
0
1
0
0
1
1
1
*7-segment digits can be replaced by directly controlled discrete LEDs according to settings in decode mode register (Table 11).
**The highlighted row is used in Typical Operating Circuit 1 for display digits 0 and 1.
______________________________________________________________________________________
31
MAX6954
Table 37. Slot 1 Configuration
CC2: 14-seg monocolor
CC3: 16-seg monocolor
CC3: (2) 7-seg monocolor*
or 7-seg bicolor
1a
a1
a1
1a
a
a
a1
1a
a
a2
—
a2
a2
—
—
—
a2
—
—
02
CC2
—
CC2
CC2
CC2
CC2
—
CC2
—
—
CC2
03
—
CC3
CC3
CC3
—
—
CC3
—
CC3
CC3
CC3
04
b
b
1b
b
b
1b
b
b
b
1b
b
05
c
c
1c
c
c
1c
c
c
c
1c
c
06
d1
d1
1d
d1
d1
1d
d
d
d1
1d
d
07
d2
d2
1dp
d2
d2
1dp
—
—
d2
1dp
—
08
e
e
1e
e
e
1e
e
e
e
1e
e
09
f
f
1f
f
f
1f
f
f
f
1f
f
010
g1
g1
1g
g1
g1
1g
g1
g1
g1
1g
g1
011
g2
g2
2a
g2
g2
2a
g2
g2
g2
2a
g2
012
h
h
2b
h
h
2b
h
h
h
2b
h
013
i
i
2c
i
i
2c
i
i
i
2c
i
CC2 and CC3: (2) 14-seg
monocolor or 14-seg
bicolor
CC2: (2) 7-seg monocolor*
or 7-seg bicolor
a1
a2
CC3: 14-seg monocolor
CC2: 16-seg monocolor
a1
01
CC2 and CC3:
(1)16-seg bicolor
CC3: 16-seg monocolor
00
CC2 and CC3:
(2) 7-seg bicolor
or (4) 7-seg monocolor
or (1) 7-seg bicolor
and (2) 7-seg monocolor*
CONFIGURATION
CHOICE
Common-Cathode
Drive: Digit Type
CC2: 16-seg monocolor
Table 38. Slot 2 Configuration
014
j
j
2d
j
j
2d
j
j
j
2d
j
015
k
k
2e
k
k
2e
k
k
k
2e
k
016
l
l
2f
l
l
2f
l
l
l
2f
l
017
m
m
2g
m
m
2g
m
m
m
2g
m
018
dp
dp
2dp
dp
dp
2dp
dp
dp
dp
2dp
dp
ADDRESS
CODE (HEX)
0x0C
D7
REGISTER DATA
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
See Table 40.
D6
D5
See Table 39.
D4
D3
D2
D1
D0
0
0
1
0
0
1
1
1
See Table 37.
*7-segment digits can be replaced by directly controlled discrete LEDs according to settings in decode mode register (Table 11).
**The highlighted row is used in Typical Operating Circuit 1 for display digits 2 and 3.
32
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
MAX6954
CC4: 14-seg monocolor
CC5: 16-seg monocolor
CC5: (2) 7-seg monocolor*
or 7-seg bicolor
1a
a1
a1
1a
a
a
a1
1a
a
a2
—
a2
a2
—
—
—
a2
—
—
02
b
b
1b
b
b
1b
b
b
b
1b
b
03
c
c
1c
c
c
1c
c
c
c
1c
c
04
CC4
—
CC4
CC4
CC4
CC4
—
CC4
—
—
CC4
05
—
CC5
CC5
CC5
—
—
CC5
—
CC5
CC5
CC5
06
d1
d1
1d
d1
d1
1d
d
d
d1
1d
d
07
d2
d2
1dp
d2
d2
1dp
—
—
d2
1dp
—
08
e
e
1e
e
e
1e
e
e
e
1e
e
09
f
f
1f
f
f
1f
f
f
f
1f
f
010
g1
g1
1g
g1
g1
1g
g1
g1
g1
1g
g1
011
g2
g2
2a
g2
g2
2a
g2
g2
g2
2a
g2
012
h
h
2b
h
h
2b
h
h
h
2b
h
013
i
i
2c
i
i
2c
i
i
i
2c
i
014
j
j
2d
j
j
2d
j
j
j
2d
j
015
k
k
2e
k
k
2e
k
k
k
2e
k
016
l
l
2f
l
l
2f
l
l
l
2f
l
017
m
m
2g
m
m
2g
m
m
m
2g
m
018
dp
dp
2dp
dp
dp
2dp
dp
dp
dp
2dp
dp
ADDRESS
CODE (HEX)
0x0C
D7
REGISTER DATA
CC4 and CC5: (2) 14-seg
monocolor or 14-seg
bicolor
CC4: (2) 7-seg monocolor*
or 7-seg bicolor
a1
a2
CC5: 14-seg monocolor
CC4: 16-seg monocolor
a1
01
CC4 and CC5:
(1)16-seg bicolor
CC5: 16-seg monocolor
00
CC4 and CC5:
(2) 7-seg bicolor
or (4) 7-seg monocolor
or (1) 7-seg bicolor
and (2) 7-seg monocolor*
CONFIGURATION
CHOICE
Common-Cathode
Drive: Digit Type
CC4: 16-seg monocolor
Table 39. Slot 3 Configuration
See Table 40.
D6
D5
D4
D3
D2
D1
D0
0
0
1
0
0
1
1
1
See Table 38.
See Table 37.
*7-segment digits can be replaced by directly controlled discrete LEDs according to settings in decode mode register (Table 11).
**The highlighted row is used in Typical Operating Circuit 1 for display digits 4 and 5.
______________________________________________________________________________________
33
CC6: 16-seg monocolor
CC6: (2) 7-seg monocolor*
or 7-seg bicolor
CC6: 14-seg monocolor
CC7: 16-seg monocolor
CC7: (2) 7-seg monocolor*
or 7-seg bicolor
a1
1a
a1
a1
1a
a
a
a1
1a
a
a2
a2
—
a2
a2
—
—
—
a2
—
—
02
b
b
1b
b
b
1b
b
b
b
1b
b
03
c
c
1c
c
c
1c
c
c
c
1c
c
04
d1
d1
1d
d1
d1
1d
d
d
d1
1d
d
05
d2
d2
1dp
d2
d2
1dp
—
—
d2
1dp
—
06
CC6
—
CC6
CC6
CC6
CC6
—
CC6
—
—
CC6
07
—
CC7
CC7
CC7
—
—
CC7
—
CC7
CC7
CC7
08
e
e
1e
e
e
1e
e
e
e
1e
e
09
f
f
1f
f
f
1f
f
f
f
1f
f
010
g1
g1
1g
g1
g1
1g
g1
g1
g1
1g
g1
011
g2
g2
2a
g2
g2
2a
g2
g2
g2
2a
g2
012
h
h
2b
h
h
2b
h
h
h
2b
h
013
i
i
2c
i
i
2c
i
i
i
2c
i
014
j
j
2d
j
j
2d
j
j
j
2d
j
015
k
k
2e
k
k
2e
k
k
k
2e
k
CC6 and CC7: (2) 14-seg
monocolor or 14-seg
bicolor
CC6 and CC7:
(1)16-seg bicolor
a1
01
CC7: 14-seg monocolor
CC7: 16-seg monocolor
00
CC6 and CC7:
(2) 7-seg bicolor
or (4) 7-seg monocolor
or (1) 7-seg bicolor
and (2) 7-seg monocolor*
CONFIGURATION
CHOICE
Common-Cathode
Drive: Digit Type
CC6: 16-seg monocolor
Table 40. Slot 4 Configuration
016
l
l
2f
l
l
2f
l
l
l
2f
l
017
m
m
2g
m
m
2g
m
m
m
2g
m
018
dp
dp
2dp
dp
dp
2dp
dp
dp
dp
2dp
dp
ADDRESS
CODE (HEX)
REGISTER DATA
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
0x0C
D7
0
1
0
1
D6
0
0
1
1
D5
D4
D3
D2
D1
D0
See Table 39.
See Table 38.
See Table 37.
*7-segment digits can be replaced by directly controlled discrete LEDs according to settings in the decode mode register (Table 11).
**The highlighted row is used in Typical Operating Circuit 1 for display digits 6 and 7.
34
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
3.3V
O0
V+
47μF
V+
O1
V+
O2
GND
GND
O3
GND
O5
100nF
O4
O6
MAX6954
O11
O12
O13
O14
O15
O16
O17
O18
O0
O1
O7
a
b
c
d
e
f
g
dp
Rcc
Gcc
O2
O4
O5
O6
O8
O9
O10
O7
a
b
c
d
e
f
g
dp
O1
O0
CC1
CC0
DIGIT 0b (RED), DIGIT 1b (GREEN)
7-SEGMENT BICOLOR LED
O8
O9
O10
CLK
O11
DIN
O12
DOUT
O13
CS
O14
O15
BLINK
O16
O17
OSC_OUT
O18
P0
OSC
P1
P2
ISET
22pF
P3
O0
O4
O5
O6
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O2
O3
a
b
c
d
e
f
g1
g2
h
i
j
k
l
m
dp
Rcc
Ccc
DIGITS 0a AND 1a
7-SEGMENT MONOCOLOR
P4
56kΩ
DIGITS 2 AND 3
14-SEGMENT BICOLOR
O0
O2
O3
O4
O0
O2
O3
O4
O5
O8
O9
O10
O5
O8
O9
O10
O11
O12
O13
O14
O11
O12
O13
O14
O15
O16
O17
O18
O15
O16
O17
O18
O6
O7
DIGIT 6
4 x 4 MATRIX OF DISCRETE MONOCOLOR LEDs
DIGIT 7
4 x 4 MATRIX OF DISCRETE MONOCOLOR LEDs
O0
O1
O2
O3
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O5
a1
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
DIGIT 5
16-SEGMENT MONOCOLOR
O0
O1
O2
O3
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O4
a1
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
DIGIT 4
16-SEGMENT MONOCOLOR
______________________________________________________________________________________
35
MAX6954
Typical Operating Circuits
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Typical Operating Circuits (continued)
3.3V
O0
V+
47μF
V+
O1
V+
O2
GND
GND
O3
GND
O5
100nF
O4
O6
MAX6954
O7
O8
O9
O10
CLK
O11
DIN
O12
DOUT
O13
CS
O14
O15
O16
BLINK
O17
OSC_OUT
O18
P0
P1
OSC
P2
P3
ISET
22pF
P4
56kΩ
O2
O3
O4
O5
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O0
a
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
O2
O3
O4
O5
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O1
a
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
DIGIT 0
O0
O1
O4
O5
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O2
a
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
DIGIT 1
O0
O1
O4
O5
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O3
a
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
DIGIT 2
O0
O1
O2
O3
O6
O6
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O4
a
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
O0
O1
O2
O3
O6
O7
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O5
DIGIT 4
36
a
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
O0
O1
O2
O3
O4
O5
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O6
DIGIT 5
a
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
DIGIT 3
O0
O1
O2
O3
O4
O5
O8
O9
O10
O11
O12
O13
O14
O15
O16
O17
O18
O7
a
a2
b
c
d1
d2
e
f
g1
g2
h
i
j
k
l
m
dp
cc
DIGIT 6
______________________________________________________________________________________
DIGIT 7
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
TOP VIEW
4
33 OSC_OUT
CLK
5
32 BLINK
CLK 5
36 BLINK
DIN
6
31 O18
DIN 6
35 O18
O0
7
30 O17
O0 7
34 O17
DIN
1
O1
8
29 O16
O1 8
33 O16
O0
2
29
O2
9
28 O15
28
32 O15
O1
O2
O3
O4
3
O2 9
4
27
O5
7
O6
O7
8
O8
10
23 O10
O7 14
27 O10
O8 15
22 O9
O8 15
26 O9
GND 16
21 V+
N.C. 16
25 N.C.
ISET 17
20 OSC
GND 17
24 V+
GND 18
19 V+
GND 18
23 V+
SSOP
ISET 19
22 OSC
GND 20
21 V+
32
34
35
36
38
EP*
O16
O15
O14
23
22
O10
21
O9
20
O7 14
9
19
28 O11
V+
N.C.
O6 13
18
24 O11
24
V+
O6 13
O18
O17
O13
O12
O11
25
17
29 O12
16
O5 12
26
MAX6954
6
15
25 O12
5
14
O5 12
31 O14
13
30 O13
MAX6954APL
GND
ISET
GND
V+
OSC
O4 11
12
O3 10
26 O13
11
27 O14
30
N.C.
O3 10
O4 11
+
GND
MAX6954AAX
37 OSC_OUT
DOUT 4
BLINK
38 P2
DOUT
31
CS 3
P2
OSC_OUT
34 P2
33
3
P1
P0
P4/IRQ
P3
39 P3
CS
37
40 P4
P1 2
DOUT
CS
P0 1
35 P3
CLK
36 P4
2
39
1
P1
40
P0
TQFN-EP
*EP = EXPOSED PAD. CONNECT EP TO GND.
PDIP
Chip Information
PROCESS: CMOS
______________________________________________________________________________________
37
MAX6954
Pin Configurations
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
36 SSOP
A36-2
21-0040
40 PDIP
P40-2
21-0044
40 TQFN
T4066-5
21-0140
38
DOCUMENT NO.
______________________________________________________________________________________
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
REVISION
NUMBER
REVISION
DATE
3
6/08
Added TQFN package option
4
3/09
Corrected errors in Tables 37–40
DESCRIPTION
PAGES
CHANGED
1, 2, 6, 37
31–34
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 ____________________ 39
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX6954
Revision History