MAX6975ATL+ Datasheet MAX6974ATL+, MAX6975ATL+, MAX6974ATL+T | P1-P3

General Description

The MAX6974/MAX6975 precision current-sinking,

24-output PWM LED drivers drive red, green, and blue

LEDs for full-color graphic message boards and video

displays. Each output has an individual 12-bit (MAX6974)

or 14-bit (MAX6975) PWM-intensity (hue) control and

7-bit (MAX6974) or 5-bit (MAX6975) global PWM intensity

(luminance) control. The MAX6974/MAX6975 feature a

high-speed, fully buffered cascadable serial interface,

open-circuit LED fault detection circuitry, as well as a

watchdog timer.

The driver has three banks of eight outputs, with each

bank intended to drive a different color in RGB applica-

tions. The full-scale current for each bank of eight out-

puts is adjustable from 6mA to 30mA in 256 steps

(0.3125% per step) to calibrate each color.

The MAX6974/MAX6975 can optionally multiplex by

using outputs MUX0 and MUX1, which each drive an

external pnp transistor. Multiplexing doubles the

MAX6974/MAX6975 drive capability to 48 LEDs.

The MAX6974/MAX6975 operate from a 3.0V to 3.6V

power supply. The LED power supply can range from

3V to 7V. The LED drivers require only 0.8V headroom

above the LEDs’ forward-voltage drop. Using a sepa-

rate LED supply voltage for each LED minimizes power

consumption.

The serial interface uses differential signaling for the

high-speed clock and data signals to reduce EMI and

improve signal integrity. The MAX6974/MAX6975 buffer

all interface signals to simplify cascading devices in

modules that use a large number of drivers.

An internal watchdog timer, when enabled, automatically

clears the pixel-data registers and blanks the display if

any of the signal inputs fail to toggle within 40ms.

The MAX6974/MAX6975 are available in 40-pin TQFN

packages and operate over the -40°C to +125°C

temperature range.

Refer to the MAX6972/MAX6973 data sheet for a

16-output, 11mA to 55mA software-compatible device.

Applications

LED Video Display Panels

LED Message Boards

Variable Message Signs (VMS)

Signs

Graphic Panels

Features

♦ 24 LED Current Sink Outputs (Three Banks of

Eight Outputs)

♦ 48 LED Drive Option When Multiplexing

♦ 33MHz Clock Supports Up to 63 Frames per

Second of Video

♦ Constant Output Current Calibration from 6mA to

30mA in 256 Steps

♦ EZCascade™ Interface Simplifies Multiple Driver

Cascading Without External Buffers

♦ 12-Bit or 14-Bit Individual PWM LED Intensity

Controls

♦ 7-Bit or 5-Bit Panel PWM-Intensity Control

♦ +3V to +7V LED Power Supply

♦ +3.0V to +3.6V Logic Supply

♦ Open-Circuit LED Fault Detection

♦ Optional Watchdog Timer Blanks Display if

Interface Fails

♦ Standard -40°C to +125°C Operating Temperature

Range

MAX6974/MAX6975

24-Output PWM LED Drivers

for Message Boards

________________________________________________________________

Maxim Integrated Products

19-0555; Rev 2; 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.

EVALUATION KIT

AVAILABLE

Typical Operating Circuit appears at the end of data sheet.

EP = Exposed paddle.

Denotes a lead-free package.

MAX6974ATL/

MAX6975ATL

TQFN-EP

TOP VIEW

4567

2728

EP*

*EP = EXPOSED PADDLE.

2930 26 24 23 22

8910

AGND

I.C.

LOADI

DIN-

DIN+

CLKI-

CLKI+

MUX0

CLKO+

CLK0-

DOUT+

DOUT-

LOADO

MUX1

Pin Configuration

Ordering Information

PART

TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX6974ATL+ -40°C to +125°C 40 TQFN-EP*

T4066-3

MAX6975ATL+ -40°C to +125°C 40 TQFN-EP*

T4066-3

EZCascade is a trademark of Maxim Integrated Products, Inc.

MAX6974/MAX6975

24-Output PWM LED Drivers

for Message Boards

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.

(All voltages with respect to GND.)

........................................................................-0.3V to +4.0V

R0–R7, G0–G7, B0–B7, MUX0, and MUX1 ...........-0.3V to +8.0V

All Other Pins..............................................-0.3V to (V

+ 0.3V)

Continuous Power Dissipation (T

= +70°C)

40-Pin TQFN (derate 37mW/°C over +70°C) .............2963mW

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Operating Supply Voltage V

3.0 3.6 V

LEDs Anode Voltage

(R0–R7, G0–G7, B0–B7, MUX0,

and MUX1)

CLKI

= 0Hz; CLKO_, DOUT_ loaded 200Ω;

calibration DACs set to 0x01

28 52

CLKI

= 0Hz; CLKO_, DOUT_ loaded 200Ω;

calibration DACs set to 0xFF

51 72

Supply Current I

CLKI

= 32MHz; CLKO_, DOUT_ loaded 200Ω;

calibration DACs set to 0xFF

54 77

Input High Voltage LOADI V

IHC

0.7

x V

Input Low Voltage LOADI V

ILC

0.3

x V

Differential Input Voltage Range

CLKI_, DIN_

±0.15 ±1.20 V

Common-Mode Input Voltage

CLKI_, DIN_

| V

I D

/ 2| 2.4 V

Differential Input High Threshold VDIFF

8 100 mV

Differential Input Low Threshold VDIFF

-100 -8 mV

Differential Output Voltage

CLKO_, DOUT_

Termination 200Ω at receiver _+ and _- inputs ±190 ±550 mV

Differential Output Offset

CLKO_, DOUT_

Termination 200Ω at receiver _+ and _- inputs 1.125 1.25 1.375 V

Input Leakage Current

CLKI_, DIN_, LOADI

, I

-1 +1 µA

Input Capacitance

CLKI_, DIN_, LOADI

10 pF

Output Low Voltage LOADO V

OLC

SINK

= 5mA 0.05 0.25 V

Output High Voltage LOADO V

OHC

SOURCE

= 5mA

- 0.5

- 0.2

ELECTRICAL CHARACTERISTICS

= 3.0V to 3.6V, T

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V

= 3.3V, T

= +85°C.) (Note 1)

MAX6974/MAX6975

24-Output PWM LED Drivers

for Message Boards

_______________________________________________________________________________________ 3

Note 1: All parameters tested at T

= +85°C. Specifications over temperature are guaranteed by design.

Note 2: Specification limits apply to devices at the same T

for T

= T

MIN

to T

MAX

Note 3: Guaranteed by design.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Output Slew Time LOADO 20% to 80%, 80% to 20%, load = 10pF 3 ns

Output Low Voltage MUX_ V

OLM

SINK

= 40mA 0.4 V

Open-Circuit Detection V

OCD

200 mV

Output Voltage Slew Time

R0–R7, G0–G7, B0–B7

80% to 20%, load = 50pF,

calibration DACs set to 0xFF

100 ns

= +85°C 29.4 30 30.6

= +125°C 29.10 30.90

Full-Scale Port Output Current

R0–R7, G0–G7, B0–B7

SINKFS

= 3.3V, V

= 1.2V,

calibration DACs set to 0xFF

= T

MIN

to T

MAX

28.2 31.8

= +125°C

(Note 3)

0.5 1.7

= +85°C 0.3 1

Port-to-Port Current Matching

R0–R7, G0–G7, B0–B7

ΔI

SINK

= 3.3V, V

= 1.2V,

calibration DACs set to 0xFF

SINK

= 30mA (Note 2)

= -40°C

(Note 3)

±0.9 3.0

= +85°C 0.3 1.15

Output Load Regulation ΔI

OLR

D D

= 3.3V , V

= 1.2V to 3.0V ,

calibration DACs set to 0x80,

SINK

= 18mA

= T

MIN

to T

MAX

1.5

mA/V

= +85°C 0.6 1.7

Output Power-Supply Rejection ΔI

OPSR

D D

= 3.0V to 3.6V , V

= 1.2V ,

calibration DACs set to 0x80,

SINK

= 18mA

= T

MIN

to T

MAX

2.0

mA/V

ELECTRICAL CHARACTERISTICS (continued)

= 3.0V to 3.6V, T

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V

= 3.3V, T

= +85°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CLKI_ Input Frequency f

CLKI

33 MHz

CLKI_ Duty Cycle 40 60 %

CLKO_ Output Delay t

PD-CLKO

19 ns

DIN_ Setup Time t

SU-DIN

0.5 ns

DIN_ Hold Time t

HD-DIN

5ns

DOUT_ Output Delay t

PD-DOUT

18 ns

LOADO Output Delay t

PD-LOADO

21 ns

LOADI Hold Time t

HD-LOADI

11 ns

Watchdog Period When enabled 40 125 300 ms

TIMING CHARACTERISTICS

= 3.0V to 3.6V, T

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at 3.3V, T

= +85°C.) (Note 1)

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P23

MAX6975ATL+

Mfr. #:

Buy MAX6975ATL+

Manufacturer:

Maxim Integrated

Description:

LED Lighting Drivers 24-Output PWM LED Driver

Lifecycle:

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MAX6975ATL+

MAX6975ATL+

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