How to Simplify LED Matrix Control: A Practical Look at the ETEK CD1628

Driving an LED matrix is not simply a matter of turning individual LEDs on and off. As the number of LEDs increases, the controller must coordinate segment and grid outputs, manage display data, control brightness, and communicate reliably with the host MCU—all while keeping the external circuit practical.

This is where an LED Matrix driver can significantly simplify the display architecture.

Instead of asking the MCU to directly manage every LED connection and timing operation, a dedicated driver IC can take over the repetitive work of scanning and refreshing the display. The ETEK CD1628 is designed for this type of application, combining LED matrix driving, display memory, key scanning, dimming control, and serial communication in a single device.

The Real Challenge Behind an LED Matrix

A conventional single LED can be controlled relatively easily. A matrix display is different.

Multiple LEDs share segment and grid lines, so the system needs to control which LEDs are active at a particular moment while repeatedly scanning the matrix fast enough to create a stable visual output.

If this work is handled entirely by an MCU, valuable processing resources and GPIOs can be consumed by display management rather than the application’s primary functions.

The CD1628 takes over this display-driving workload with 10 segment outputs, 4 grid outputs, and 3 configurable segment/grid outputs. Depending on the selected display mode, it supports configurations ranging from 10 segments × 7 grids to 13 segments × 4 grids, with support for up to 70 LEDs in a matrix.

This gives designers more flexibility to adapt the same driver architecture to different display layouts.

One Driver for Display Data and Matrix Scanning

An LED Matrix driver needs to do more than provide output pins. It must also organize the information being displayed.

The CD1628 integrates display memory and a control circuit, allowing display data to be stored within the device rather than requiring the MCU to continuously maintain every output state.

The device provides display memory addresses from 00H to 0DH, while display data can be written through its serial interface. It also supports automatic address increase or fixed-address operation, giving developers flexibility in how display information is transferred.

For an embedded system, this means the MCU can send display information to the CD1628 and leave the driver to handle the corresponding matrix-driving process.

That separation can make the overall system architecture easier to manage.

Brightness Control Without Redesigning the LED Circuit

Display brightness is another practical consideration.

A display that looks appropriate in a dark environment may appear too dim under stronger ambient light, while excessive brightness can increase power consumption and create an uncomfortable viewing experience.

The CD1628 provides 8-step dimming adjustment through its display control settings. Its duty-cycle options range from 1/16 to 14/16, allowing the display output to be adjusted without changing the fundamental LED matrix hardware.

For products that operate under different lighting conditions or require configurable display intensity, this built-in control provides a useful level of flexibility.

Display Control and Key Scanning in the Same IC

One particularly useful aspect of the CD1628 is that it is not limited to LED output.

The device also integrates a 2 × 10 key scanning matrix. Ten segment/scan lines can be used for keyboard scanning, while two key inputs provide the corresponding input paths. Key data is stored in internal RAM and can be read through the serial communication interface.

This can be valuable in appliances and other user-interface products where a display and physical buttons need to coexist.

Instead of designing separate ICs for LED matrix control and key scanning, engineers can combine these functions around a single CD1628, potentially reducing component count and simplifying communication between the display interface and the MCU.

A Simple Three-Line Interface Between the MCU and Display

Communication complexity is another factor engineers need to consider when selecting an LED Matrix driver.

The CD1628 uses a 3-line serial interface consisting of DIO, CLK, and STB. DIO serves as the serial data input/output port, while CLK provides the serial clock and STB controls data strobe operation.

The device also incorporates a built-in 12 kΩ typical pull-up resistance and an internal RC oscillator, reducing the number of external functions required for basic operation.

For embedded designs, this provides a relatively straightforward communication path between the MCU and the display driver.

Designed for Practical Embedded Display Applications

The CD1628 operates from a 3V to 5.5V supply range and uses a high-performance CMOS process designed for low power consumption. Its specified operating temperature range is -40°C to 85°C, making it suitable for a variety of embedded electronic products.

At 5V, the device supports segment output current of up to 60 mA under the specified test conditions, while the grid outputs provide up to 100 mA typical low-level output current under the corresponding conditions. The maximum total output driver current is specified as 250 mA.

The CD1628 is available in an SOP28 package, providing a conventional package option for applications where board space and manufacturing compatibility need to be balanced.

Where Can the ETEK CD1628 Be Used?

The combination of matrix LED driving, key scanning, display memory, dimming, and serial communication makes the CD1628 suitable for applications where a compact embedded user interface is required.

ETEK identifies applications including:

– Household appliances

– Toy displays

– Smart portable devices

– Smart audio products

These applications often require a display and user-input interface without dedicating a large portion of the main MCU’s resources to display management.

Choosing an LED Matrix Driver Around the System Architecture

The right LED Matrix driver should be evaluated not only by the number of LEDs it can drive, but also by how well its architecture fits the rest of the system.

For engineers, the key questions include: How many segment and grid lines are required? Is display memory integrated? Does the application need brightness adjustment? Can key scanning be handled by the same device? How much communication overhead will the MCU have?

The ETEK CD1628 addresses these requirements through matrix configurations supporting up to 70 LEDs, integrated display memory, 8-step dimming, 2 × 10 key scanning, a three-line serial interface, and an internal RC oscillator.

For embedded products that need both LED display control and user-input functionality, integrating these functions into one LED Matrix driver can provide a more structured approach to display-system design.

Explore the ETEK CD1628 Matrix LED Driver for detailed specifications and design information.

✉️Request Sample: https://www.etekmicro.com/sample/