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24-Output PWM LED Drivers for Message Boards

EZCascade™ LVDS Serial Interface Running at 35Mbps for Easy and Economical Designing and Manufacturing of Large Displays

Product Details

Key Features

Simplified Block Diagram

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Key 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

Applications/Uses

  • Graphic Panels
  • LED Message Boards
  • LED Video Display Panels
  • Signs
  • Variable Message Signs (VMS)

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 applications. The full-scale current for each bank of eight outputs 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 active-low MUX0 and active-low 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 separate 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.

Simplified Block Diagram

MAX6974, MAX6975: Typical Operating Circuit MAX6974, MAX6975: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.