General Description
The MAX6971 serial-interfaced LED driver provides 16
open-drain, constant-current-sinking LED driver outputs
rated at 36V. The MAX6971 operates from a 3V to 5.5V
supply. The MAX6971 supply and the LEDs’ supply or
supplies can power up in any order. The constant-current outputs are programmed together to up to 55mA
using a single external resistor. The MAX6971 operates
with a 25Mb, industry-standard, 4-wire serial interface.
The MAX6971 uses the industry-standard, shift-registerplus-latch-type serial interface. The driver accepts data
shifted into a 16-bit shift register using data input DIN
and clock input CLK. Input data appears at the DOUT
output 16 clock cycles later to allow cascading of multiple MAX6971s. The latch-enable input, LE, loads the 16
bits of shift register data into a 16-bit output latch to set
which LEDs are on and which are off. The outputenable, OE, gates all 16 outputs on and off, and is fast
enough to be used as a PWM input for LED intensity
control.
For applications requiring LED fault detection, refer to
the MAX6983, which automatically detects open-circuit
LEDs.
For safety-related applications requiring a watchdog
timer, refer to the MAX6983, which includes a fail-safe
feature that blanks the display if the serial interface
becomes inactive for more than 1s.
The MAX6971 is one of a family of 12 shift-register-pluslatch-type LED drivers. The family includes 8-port and
16-port types, with 5.5V- or 36V-rated LED outputs, with
and without open-circuit LED detection and watchdog.
All versions operate from a 3V to 5.5V supply, and are
specified over the -40°C to +125°C temperature range.
Features
♦ 25Mb, Industry-Standard, 4-Wire Serial Interface
♦ 3V to 5.5V Logic Supply
♦ 16 Constant-Current LED Outputs Rated at 36V
♦ Up to 55mA Continuous Current per Output
♦ Output Current Programmed by Single Resistor
♦ 3% Current Matching Between Outputs
♦ 6% Current Matching Between ICs
♦ High-Dissipation, 24-Pin Packages
♦ -40°C to +125°C Temperature Range
MAX6971
16-Port, 36V Constant-Current LED Driver
________________________________________________________________ Maxim Integrated Products 1
24
23
22
21
20
19
18
17
1
2
3
4
5
6
7
8
V+
SET
DOUT
OELE
CLK
DIN
GND
TOP VIEW
OUT15
OUT14
OUT13
OUT12OUT3
OUT2
OUT1
OUT0
16
15
14
13
9
10
11
12
OUT11
OUT10
OUT9
OUT8OUT7
OUT6
OUT5
OUT4
TSSOP/PDIP
MAX6971AUG
MAX6971ANG
Pin Configuration
Ordering Information
19-3808; Rev 1; 10/07
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.
Typical Application Circuit and Selector Guide appear at
end of data sheet.
Applications
Variable Message Signs
Marquee Displays
Point-of-Order Signs
Traffic Signs
Gaming Features
Architectural Lighting
PART TEMP RANGE PIN-PACKAGE
MAX6971AUG
-40°C to +125°C
-40°C to +125°C
MAX6971
16-Port, 36V Constant-Current LED Driver
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
Voltage with respect to GND.
V+ ............................................................................-0.3V to +6V
OUT_ .....................................................................-0.3V to +40V
DIN, CLK, LE, OE, SET ................................-0.3V to (V+ + 0.3V)
DOUT Current ..................................................................±10mA
OUT_ Sink Current .............................................................60mA
Total GND Current ...........................................................960mA
Continuous Power Dissipation (TA= +70°C)
24-Pin TSSOP (derate 12.2mW/°C over +70°C) ..........975mW
24-Pin PDIP (derate 13.3mW/°C over +70°C)............1067mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(Typical Operating Circuit, V+ = 3V to 5.5V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V+ = 5V, TA= +25°C.)
(Note 1)
Operating Supply Voltage V+ 3.0 5.5 V
Output Voltage V
OUT
36 V
Standby Current
(Interface Idle, All Output Ports
High Impedance, R
SET
= 360Ω)
I
+
All logic inputs at V+ or GND, DOUT
unloaded
5.7 8 mA
Standby Current
(Interface Running, All Output
Ports High Impedance,
R
SET
= 360Ω)
I
+
f
CLK
= 5MHz, OE = V+, DIN and LE = V+
or GND, DOUT unloaded
6 8.5 mA
Supply Current
(Interface Idle, All Output Ports
Active Low, R
SET
= 360Ω)
I
+
All logic inputs at V+ or GND,
DOUT unloaded
18 25 mA
Input High Voltage
DIN, CLK, LE, OE
V
IH
0.7 x
V+
V
Input Low Voltage
DIN, CLK, LE, OE
V
IL
0.3 x
V+
V
Hysteresis Voltage
DIN, CLK, LE, OE
ΔV
I
0.8 V
Input Leakage Current
DIN, CLK, LE, OE
I
IH
, I
IL
-1 +1 µA
Output High-Voltage DOUT V
OH
I
SOURCE
= 4mA
V +
V
Output Low Voltage V
OL
I
SINK
= 4mA 0.5 V
Output Current OUT_ I
OUT
V+ = 3V to 5.5V, V
OUT
= 0.8V to 2.5V,
R
SET
= 360Ω
37 50 61 mA
Output Leakage Current OUT_ I
LEAK
OE = V+ 1 µA
Note 1: All parameters tested at TA= +25°C. Specifications over temperature are guaranteed by design.
- 0.5V
MAX6971
16-Port, 36V Constant-Current LED Driver
_______________________________________________________________________________________ 3
5V TIMING CHARACTERISTICS
(Typical Operating Circuit, V+ = 4.5V to 5.5V, TA= T
MIN
to T
MAX
, unless otherwise noted.) (Notes 1, 2, 3)
CLK Clock Period t
CP
40 ns
CLK Pulse-Width High t
CH
19 ns
CLK Pulse-Width Low t
CL
19 ns
DIN Setup Time t
DS
4ns
DIN Hold Time t
DH
8ns
DOUT Propagation Delay t
DO
12 32 ns
DOUT Rise and Fall Time
C
DOUT
= 10pF, 20% to 80% 10 ns
LE Pulse-Width High t
LW
20 ns
LE Setup Time t
LS
10 ns
LE Rising to OUT_ Rising Delay t
LRR
(Note 3) 100 ns
LE Rising to OUT_ Falling Delay t
LRF
(Note 3) 300 ns
t
OEL
(Note 3) 320 ns
LED Output OUT_ Turn-On Fall
Time
t
f
80% to 20%, pullup resistor = 65Ω 120 ns
LED Output OUT_ Turn-Off Rise
Time
t
r
20% to 80%, pullup resistor = 65Ω 120 ns
Note 1: All parameters tested at TA= +25°C. Specifications over temperature are guaranteed by design.
Note 2: See Figure 3.
Note 3: A 65Ω pullup resistor connected from OUT_ to 5.5V.
CLK Rising to OUT_ Rising Delay
CLK Rising to OUT_ Falling Delay
OE Rising to OUT_ Rising Delay
OE Falling to OUT_ Falling Delay
SYMBOL
t
DR, tDF
MIN TYP MAX
MAX6971
16-Port, 36V Constant-Current LED Driver
4 _______________________________________________________________________________________
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
3.3V TIMING CHARACTERISTICS
(Typical Operating Circuit, V+ = 3V to 5.5V, TA= T
MIN
to T
MAX
, unless otherwise noted.) (Notes 1, 2)
CLK Clock Period t
CP
52 ns
CLK Pulse-Width High t
CH
24 ns
CLK Pulse-Width Low t
CL
24 ns
DIN Setup Time t
DS
4ns
DIN Hold Time t
DH
8ns
DOUT Propagation Delay t
DO
12 50 ns
DOUT Rise and Fall Time
C
DOUT
= 10pF, 20% to 80% 12 ns
LE Pulse-Width High t
LW
20 ns
LE Setup Time t
LS
15 ns
LE Rising to OUT_ Rising Delay t
LRR
(Note 3) 120 ns
LE Rising to OUT_ Falling Delay t
LRF
(Note 3) 310 ns
t
OEL
(Note 3) 330 ns
LED Output OUT_ Turn-On Fall
Time
t
f
80% to 20% (Note 3) 120 ns
LED Output OUT_ Turn-Off Rise
Time
t
r
20% to 80% (Note 3) 120 ns
Note 1: All parameters tested at TA= +25°C. Specifications over temperature are guaranteed by design.
Note 2: See Figure 3.
Note 3: A 65Ω pullup resistor connected from OUT_ to 5.5V.
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS OFF,
R
SET
= 720Ω)
MAX6971 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.04.53.5 4.0
1.85
1.90
1.95
2.00
1.80
3.0 5.5
TA = +125°C
TA = +85°C
TA = -40°C
TA = +25°C
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS OFF,
R
SET
= 360Ω)
MAX6971 toc02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.04.53.5 4.0
3.55
3.60
3.65
3.70
3.50
3.0 5.5
TA = +125°C
TA = +85°C
TA = -40°C
TA = +25°C
10
30
25
20
15
35
40
3.0 4.03.5 4.5 5.0 5.5
MAX6971 toc03
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS ON, R
SET
= 720Ω)
TA = +125°C
TA = +85°C
TA = +25°C
TA = -40°C
SYMBOL
MIN TYP MAX
t
DR, tDF
CLK Rising to OUT_ Rising Delay
CLK Rising to OUT_ Falling Delay
OE Rising to OUT_ Rising Delay
OE Falling to OUT_ Falling Delay