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MAX6954AAX+

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
4 _______________________________________________________________________________________
Typical Operating Characteristics
(V+ = 3.3V, LED forward voltage = 2.4V, typical application circuit, T
A
= +25°C, unless otherwise noted.)
TIMING CHARACTERISTICS
(
Typical Operating Circuits
, V+ = 2.7V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
TIMING CHARACTERISTICS
CLK Clock Period t
CP
38.4
ns
CLK Pulse Width High t
CH
16 ns
CLK Pulse Width Low t
CL
16 ns
CS Fall to CLK Rise Setup Time t
CSS
9.5 ns
CLK Rise to CS Rise Hold Time t
CSH
0ns
DIN Setup Time t
DS
9.5 ns
DIN Hold Time t
DH
0ns
V+ = 3.0V to 5.5V 19
Output Data Propagation Delay t
DO
V+ = 2.7V 25
ns
DOUT Output Rise and Fall Times t
FT
C
LOAD
= 10pF, V+ = 3.0V to 5.5V 10
Minimum CS Pulse High t
CSW
19.5
ns
Note 1: All parameters tested at T
A
= +25°C. Specifications over temperature are guaranteed by design.
100ns/div
OSC: 500mV/div
OSC_OUT: 2V/div
MAX6954 toc03
OSC
0V
0V
OSC_OUT
INTERNAL OSCILLATOR WAVEFORM
AT OSC AND OSC_OUT PINS
R
SET
= 56kΩ
C
SET
= 22pF
MAX6954
4-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(V+ = 3.3V, LED forward voltage = 2.4V, typical application circuit, T
A
= +25°C, unless otherwise noted.)
DEAD CLOCK OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
MAX6954 toc04
SUPPLY VOLTAGE (V)
OSCILLATOR FREQUENCY (kHz)
5.04.54.03.53.0
85
95
105
110
80
2.5 5.5
R
SET
= 56kΩ
OSC = GND
100
90
SEGMENT SOURCE CURRENT
vs. SUPPLY VOLTAGE
MAX6954 toc05
SUPPLY VOLTAGE (V)
CURRENT NORMALIZED TO 40mA
5.04.54.03.53.0
0.94
0.98
1.00
1.02
0.92
2.5 5.5
V
LED
= 1.8V
0.96
1V/div
200μs/div
MAX6954 toc06
O0
O18
WAVEFORM AT PINS O0 AND O18,
MAXIMUM INTENSITY
0V
0V
GPIO SINK CURRENT
vs. TEMPERATURE
MAX6954 toc07
TEMPERATURE (°C)
GPIO SINK CURRENT (mA)
11050 8020-10
5
10
15
20
25
30
35
40
45
0
-40
V
CC
= 3.3V
V
CC
= 2.5V
V
CC
= 5.5V
OUTPUT = LOW
V
PORT
= 0.6V
PORT INPUT PULLUP CURRENT
vs. TEMPERATURE
MAX6954 toc08
TEMPERATURE (°C)
KEY-SCAN SOURCE CURRENT (mA)
11050 8020-10
0.05
0.10
0.15
0.20
0.25
0.30
0
-40
V
CC
= 3.3V
V
CC
= 2.5V
V
CC
= 5.5V
OUTPUT = HIGH
V
PORT
= 1.4V
400μs/div
KEY_A: 1V/div
IRQ: 2V/div
MAX6954 toc09
KEY_A
0V
0V
IRQ
KEYSCAN OPERATION
(KEY_A AND IRQ)
MAX6954
Detailed Description
The MAX6954 is a serially interfaced display driver that
can drive up to 16 digits 7-segment, 8 digits 14-seg-
ment, 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 addi-
tion of the following common symbols: £, €, ¥, °, µ, ±,
↑, and ↓. Seven bits represent the 104-character font
map; an 8th bit is used to select whether the decimal
point (DP) is lit. Seven-segment LED digits may be con-
trolled directly or use the hexadecimal font. Direct seg-
ment 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-compati-
ble 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
6 _______________________________________________________________________________________
Pin Description
PIN
SSOP
PDIP
T Q F N - EP
NAME
FUNCTION
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.
3338CS
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.
5540CLK
S er i al - C l ock Inp ut. On C LK’ s r i si ng ed g e, d ata shi fts i nto the i nter nal shi ft r eg i ster . On
C LK’ s fal l i ng ed g e, d ata i s cl ocked out of D OU T. C LK i s acti ve onl y w hi l e C S i s l ow .
661DIN
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
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.
16, 18
17, 18, 20 12, 13, 15
GND Ground
17 19 14 ISET
Segment Current Setting. Connect ISET to GND through series resistor R
SET
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 C
SET
from OSC
to GND. To use external clock, drive OSC with a 1MHz to 8MHz CMOS clock.
32 36 31
BLINK
Blink Clock Output. Output is open drain.
33 37 32
O S C _O U T
Clock Output. OSC_OUT is a buffered clock output to allow easy blink
synchronization of multiple MAX6954s. Output is push-pull.
— 16, 25 11, 20 N.C. Not Connected Internally
———EP
Exposed Pad (TQFN package only). Internally connected to GND. Connect to a
large ground plane to maximize thermal performance.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39

MAX6954AAX+

Mfr. #:
Buy MAX6954AAX+
Manufacturer:
Maxim Integrated
Description:
LED Display Drivers 2.7-5.5V LED Display Driver
Lifecycle:
New from this manufacturer.
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