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+ = 2.5V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 1)
PARAMETER
Operating Supply Voltage
Shutdown Supply Current
SYMBOL
V+
I
SHDN
All digital inputs at
V+ or GND
All ports programmed
As outputs high, no load,
All other inputs at V+ or
GND
All ports programmed
As outputs low, no load,
All other inputs at V+ or
GND
All ports programmed
as LED outputs, all LEDs
off, no load, all other
inputs at V+ or GND
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= T
MIN
to T
MAX
0.7 ×
V+
0.3 ×
V+
GPIO inputs without pullup,
V
PORT
= V+ to GND
V+ = 2.5V
V+ = 5.5V
GPIO outputs, I
SOURCE
= 2mA, T
A
= -40°C to
+85°C
GPIO outputs, I
SOURCE
= 1mA,
T
A
= T
MIN
to T
MAX
(Note 2)
-100
12
80
V+ -
0.7
V+ -
0.7
±1
19
120
0.3
+100
30
180
110
170
180
CONDITIONS
MIN
2.5
5.5
TYP
MAX UNITS
5.5
8
10
11
230
250
270
210
230
240
135
140
145
µA
µA
µA
µA
V
Operating Supply Current
I
GPOH
Operating Supply Current
I
GPOL
Operating Supply Current
INPUTS AND OUTPUTS
Logic-High Input Voltage
Port Inputs
Logic-Low Input Voltage
Port Inputs
Input Leakage Current
GPIO Input Internal Pullup to V+
Hysteresis Voltage GPIO Inputs
I
LED
V
IH
V
IL
I
IH
, I
IL
I
PU
DV
I
V
OH
V
V
nA
µA
V
V
V
Output High Voltage
www.maximintegrated.com
Maxim Integrated
│
2
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
Electrical Characteristics (continued)
(Typical Operating Circuit, V+ = 2.5V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 1)
PARAMETER
Port Sink Current
Output Short-Circuit Current
SYMBOL
I
OL
I
OLSC
V
PORT
= 0.6V
Port configured output low, shorted to V+
V+ = 2.5V, V
LED
= 2.3V at maximum LED
current
Port Drive LED Sink Current,
Port Configured as LED Driver
I
PORT
V+ = 3.3V, V
LED
= 2.4V at maximum LED
current (Note 2)
V+ = 5.5V, V
LED
= 2.4V at maximum LED
current
Port Drive Logic Sink Current,
Port Configured as LED Driver
Port LED Sink Current Matching
Input High-Voltage SCLK, DIN,
CS
Input Low-Voltage SCLK, DIN,
CS
Input Leakage Current SCLK,
DIN,
CS
Output High-Voltage DOUT
Output Low-Voltage DOUT
V+ = 2.5V, V
OUT
= 0.6V at maximum LED
current
V+ = 5.5V, V
OUT
= 0.6V at maximum LED
current
V+ ≤ 3.3V
V+ > 3.3V
CONDITIONS
MIN
2
2.75
9.5
18.5
19
18.5
19
TYP
10
11
13.5
24
25
23
24
6
1.6
2
0.6
-50
I
SOURCE
= 1.6mA
I
SINK
= 1.6mA
V+ -
0.5
0.4
+50
MAX UNITS
18
20
18
27.5
30
28.0
mA
28
%
V
V
nA
V
V
mA
mA
mA
I
PORT_SC
∆I
PORT
V
IH
V
IL
I
IH
, I
IL
V
OH
V
OL
Timing Characteristics (Figure 3)
3(V+ = 2.5V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 1)
PARAMETER
CLK Clock Period
CLK Pulse Width High
CLK Pulse Width Low
CS
Fall to SCLK Rise Setup Time
CLK Rise to
CS
Rise Hold Time
DIN Setup Time
DIN Hold Time
Output Data Propagation Delay
Minimum
CS
Pulse High
SYMBOL
t
CP
t
CH
t
CL
t
CSS
t
CSH
t
DS
t
DH
t
DO
t
CSW
C
LOAD
= 25pF
19
CONDITIONS
MIN
38.4
19
19
9.5
0
9.5
0
21
TYP
MAX
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 1:
All parameters tested at T
A
= +25°C. Specifications over temperature are guaranteed by design.
Note 2:
Guaranteed by design.
www.maximintegrated.com
Maxim Integrated
│
3
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
Typical Operating Characteristics
(R
ISET
= 39kΩ, T
A
= +25°C, unless otherwise noted.)
MAX6957 toc01
MAX6957 toc02
0.36
SUPPLY CURRENT (mA)
0.32
0.28
0.24
0.20
0.16
0.12
0.08
0.04
0
V+ = 2.5V TO 5.5V
NO LOAD
8
7
SUPPLY CURRENT (A)
V+ = 3.3V
6
5
4
V+ = 2.5V
V+ = 5.5V
ALL PORTS LED (ON)
ALL PORTS
OUTPUT (1)
ALL PORTS
OUTPUT (0)
SUPPLY CURRENT (mA)
10
ALL PORTS OUTPUT (1)
1
ALL PORTS OUTPUT (0)
0.1
ALL PORTS LED (OFF)
ALL PORTS LED (OFF)
3
-40.0
-12.5
15.0
42.5
70.0
97.5
125.0
-40.0
-12.5
15.0
42.5
70.0
97.5
125.0
0.01
TEMPERATURE (°C)
TEMPERATURE (°C)
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
V+ (V)
MAX6957 toc04
26
24
PORT SINK CURRENT (mA)
22
20
18
16
14
12
10
8
6
2.0
LED DRIVER SINK CURRENT vs. V+
27
26
PORT SINK CURRENT (mA)
25
24
23
22
21
2.5
3.0
3.5
4.0
4.5
5.0
5.5
20
-40.0
LED DRIVER SINK CURRENT
vs. TEMPERATURE
MAX6957 toc05
V
LED
= 2.4V
PORT SINK CURRENT (mA)
V+ = 5.5V
16
14
12
10
8
6
4
V+ = 2.5V TO 5.5V, V
PORT
= 0.6V
LED DROP = 2.4V
LED DROP = 1.8V
V+ = 3.3V
V+ (V)
-12.5
15.0
42.5
70.0
97.5
125.0
2
-40.0
-12.5
15.0
42.5
70.0
97.5
125.0
TEMPERATURE (°C)
TEMPERATURE (°C)
GPO SOURCE CURRENT vs. TEMPERATURE
(OUTPUT = 1)
V
PORT
= 1.4V
V+ = 5.5V
V+ = 3.3V
V+ = 2.5V
8
7
6
5
4
3
2
-40.0
-12.5
15.0
42.5
70.0
97.5
125.0
MAX6957 toc07
MAX6957 toc08
PORT SOURCE CURRENT (mA)
PULLUP CURRENT (A)
V+ = 5.5V
100
V+ = 3.3V
V+ = 2.5V
10
PORT CURRENT (mA)
GPO = 0, PORT
SHORTED TO V+
10
GPO = 1, PORT
SHORTED TO GND
97.5
125.0
1
-40.0
-12.5
15.0
42.5
70.0
97.5
125.0
-40.0
-12.5
15.0
42.5
70.0
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
www.maximintegrated.com
Maxim Integrated
│
4
MAX6957 toc09
9
1000
GPI PULLUP CURRENT
vs. TEMPERATURE
100
GPO SHORT-CIRCUIT CURRENT
vs. TEMPERATURE
MAX6957 toc06
18
GPO SINK CURRENT vs. TEMPERATURE
(OUTPUT = 0)
MAX6957 toc03
0.40
OPERATING SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
100
OPERATING SUPPLY CURRENT vs. V+
(NO LOADS)
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
Pin Description
PIN
NAME
28 SSOP
36 SSOP
40 TQFN
28 PDIP
1
2, 3
4
5–24
1
2, 3
4
—
36
37, 38,
39
40
—
1–10,
12–19,
21–30
32
33
34
35
11, 20,
31
EP
ISET
GND
DOUT
P12–P31
FUNCTION
Segment Current Setting. Connect ISET to GND through a resistor (R
ISET
) to set
the maximum segment current.
Ground
4-Wire Serial Data Output Port
LED Segment Drivers and GPIO. P12 to P31 can be
configured
as CA LED drivers,
GPIO outputs, CMOS logic inputs, or CMOS logic inputs with weak pullup resistor.
LED Segment Drivers and GPIO. P4 to P31 can be
configured
as CA LED drivers,
GPIO outputs, CMOS logic inputs, or CMOS logic inputs with weak pullup resistor.
4-Wire Serial Clock Input Port
4-Wire Serial Data Input Port
4-Wire Chip-Select Input, Active-Low
Positive Supply Voltage. Bypass V+ to GND with a minimum 0.047µF capacitor.
No Connection. Not internally connected.
Exposed Pad. Internally connected to GND. Connect to large ground plane for
maximum thermal dissipation. Do not use as sole ground connection.
—
25
26
27
28
—
—
5–32
33
34
35
36
—
—
P4–P31
SCLK
DIN
CS
V+
N.C.
EP
Detailed Description
The MAX6957 LED driver/GPIO peripheral provides up
to 28 I/O ports, P4 to P31, controlled through an SPI-
compatible serial interface. The ports can be configured
to any combination of constant-current LED drivers, logic
inputs and logic outputs, and default to logic inputs on
power-up. When fully configured as an LED driver, the
MAX6957 controls up to 28 LED segments with individual
16-step adjustment of the constant current through each
LED segment. A single resistor sets the maximum seg-
ment current for all segments, with a maximum of 24mA
per segment. The MAX6957 drives any combination of
discrete LEDs and CA digits, including seven-segment
and starburst alphanumeric types.
Figure 1 is the MAX6957 functional diagram. Any I/O
port can be configured as a push-pull output (sink-
ing 10mA, sourcing 4.5mA), or a Schmitt-trigger logic
input. Each input has an individually selectable internal
As time goes by, people are increasingly concerned about their own and their families' health. However, existing monitoring devices for individual vital signs have struggled to gain market share du...[详细]
C++ 属于面向对象的编程语言，OOP的思想不必多说，特别对于复杂的软件工程来说，利用OOP绝对是事半功倍，相对于传统的C来说； 当然用C来写单片机程序无可厚非，已经延续了一个传统，从大学时学的开始到工作岗位，好多人都是一直用C来做，但是既然Keil支持C++编译， 可以用C++来编写你的代码，可以利用高级语言来结构化，清晰化你的程序，为嘛不用呢！哈哈，个人看法！下面进入正题： C+...[详细]
综合技术交流
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
