Rainbow Electronics MAX6971 User Manual

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 0; 7/05

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

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

24 TSSOP

MAX6971ANG

24 Narrow PDIP

*Future product—contact factory for availability.

-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)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

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

∆V

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)

PARAMETER

CONDITIONS

UNITS

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

CRR

(Note 3) 100 ns

t

CRF

(Note 3) 310 ns

t

OEH

(Note 3) 100 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)

PARAMETER

CONDITIONS

UNITS

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

CRR

(Note 3) 120 ns

t

CRF

(Note 3) 330 ns

t

OEH

(Note 3) 120 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