LED displays can use many microcontroller pins if they are wired directly. This is why LED display driver chips are so useful. A display driver handles multiplexing, segment control and brightness control, while the microcontroller only sends the data that should appear on the display.
This article compares four common LED display driver options: MAX7219, TM1637, TM1638 and CH423S. They are often used with 7-segment displays, LED matrices, buttons and small front-panel modules, but they are not interchangeable.
Why Use a Display Driver?
A multi-digit 7-segment display or LED matrix contains many LEDs. Without a driver chip, the microcontroller must control segment lines, digit lines, timing and current limiting. This quickly becomes messy.
A display driver simplifies the project by handling repetitive display work.
- Reduces the number of microcontroller pins needed
- Handles display multiplexing
- Provides brightness control
- Makes multi-digit displays easier to use
- Can reduce software timing burden
- Some drivers also support buttons or general I/O
The right driver depends on the display type, communication interface, number of digits, need for buttons and available Arduino libraries.
MAX7219: Classic Driver for 7-Segment Displays and LED Matrices
The MAX7219 is a well-known LED display driver commonly used with 8-digit 7-segment displays and 8x8 LED matrix modules. It uses a simple serial interface and is supported by many Arduino libraries.
- Common for 8-digit 7-segment displays
- Common for 8x8 LED matrix modules
- Handles multiplexing internally
- Brightness control included
- Modules can often be chained
- Very common in Arduino examples
The MAX7219 is a good choice when the project needs a standard, well-supported 7-segment or LED matrix driver.
TM1637: Simple Driver for Small 4-Digit Displays
The TM1637 is commonly found on small 4-digit 7-segment display modules. It uses a two-wire interface that is not standard I2C, but it is simple and widely supported by Arduino libraries.
- Very common on 4-digit 7-segment display modules
- Uses only two signal wires
- Simple to use for clocks, counters and small meters
- Brightness control included
- Low-cost modules are widely available
- Usually best for small numeric displays
The TM1637 is often the easiest solution when the project only needs a small 4-digit numeric display.
TM1638: Display Driver With Key Scan Support
The TM1638 is often used on modules that combine 7-segment displays, LEDs and push buttons. It is useful for simple control panels where the display and buttons are handled by one chip.
- Can drive 7-segment displays and LEDs
- Includes key scan support for buttons
- Useful for simple front panels
- Common on display-and-button modules
- Uses a serial interface
- Good for menu input and status display combinations
The TM1638 is a practical choice when the project needs both display output and button input in one module.
CH423S: I2C Display and I/O Expansion
The CH423S is useful in projects where LED display control and I/O expansion are needed through an I2C-style interface. It can be used for multi-digit 7-segment display modules and additional digital I/O functions, depending on the module design.
- I2C-compatible control style
- Useful for multi-digit 7-segment displays
- Can provide additional I/O features depending on design
- Good fit for modular I2C systems
- Allows display control through the same bus as other I2C modules
- Less common in beginner examples than MAX7219 or TM1637
The CH423S is especially interesting when the display should be part of an I2C-based modular system instead of using a separate SPI-like or custom two-wire interface.
Main Comparison Table
| Feature | MAX7219 | TM1637 | TM1638 | CH423S |
|---|---|---|---|---|
| Common display type | 8-digit 7-segment displays and 8x8 LED matrices | Small 4-digit 7-segment displays | 7-segment displays with LEDs and buttons | Multi-digit 7-segment displays and I/O expansion designs |
| Typical interface | Serial SPI-like interface | Two-wire custom interface | Serial interface | I2C-compatible interface |
| Best known use | LED matrix modules and 8-digit displays | 4-digit clock-style displays | Display plus button modules | I2C-based multi-digit display modules |
| Button support | No | No, not normally used for buttons | Yes, key scan support | Can provide I/O features depending on circuit design |
| Brightness control | Yes | Yes | Yes | Depends on display configuration and driver setup |
| Module chaining | Common on MAX7219 matrix modules | Not the usual use | Not the usual use | Usually handled as I2C device addressing / module design |
| Beginner library availability | Very good | Very good | Good | More specialized |
| Best for | Standard LED matrix or 8-digit numeric projects | Simple 4-digit numeric projects | Front panels with display and buttons | I2C modular display systems and display/I/O combinations |
Interface Differences
These drivers do not all use the same communication method.
- MAX7219 uses a simple serial interface that is often treated like SPI
- TM1637 uses a two-wire custom protocol, not normal I2C
- TM1638 uses a serial interface for display and key data
- CH423S is controlled through an I2C-compatible bus
This matters when combining several modules in one project. If the system is already built around I2C sensors and modules, an I2C display driver can be convenient. If the project already uses SPI, a MAX7219 display may fit well.
MAX7219 for LED Matrices
The MAX7219 is especially popular for 8x8 LED matrix modules. These modules often allow multiple boards to be chained together to create longer displays.
- Good for scrolling text
- Good for symbols and simple animations
- Common in Arduino examples
- Multiple matrix modules can often be connected in series
- Useful for compact signs and visual indicators
If the project is an LED matrix display, MAX7219 is usually one of the first driver options to consider.
MAX7219 for 7-Segment Displays
The MAX7219 is also commonly used for 8-digit 7-segment displays. It handles digit multiplexing and segment current control, making it easier to display numbers, time and short codes.
- Good for 8-digit numeric displays
- Useful for clocks and counters
- Good library support
- Brightness can be controlled in software
- More capable than needed for very small 4-digit displays
TM1637 for Simple 4-Digit Displays
The TM1637 is commonly seen on small 4-digit modules, often with a colon in the middle for clock projects. It is simple, cheap and easy to connect.
- Only two signal wires
- Good for clocks
- Good for small counters
- Good for voltage or temperature readouts
- Small and inexpensive modules are common
If the project needs only four digits, a TM1637 module is often simpler than using a larger MAX7219 display.
TM1638 for Buttons and Display Together
The TM1638 becomes interesting when the project needs buttons as well as a display. Many TM1638 modules include 8 buttons, 8 LEDs and 7-segment digits on the same board.
- Good for simple control panels
- Useful for menu navigation
- Combines inputs and outputs
- Reduces wiring compared with separate buttons and display
- Useful for test fixtures and user interfaces
For projects with display and button input, TM1638 can be more useful than a display-only driver.
CH423S for I2C Modular Systems
The CH423S is a good fit when a project is designed around I2C modules. Instead of adding a separate display interface, the display can live on the same bus as sensors, RTC modules, ADCs, DACs and I/O expanders.
- Good for I2C-based modular hardware
- Useful where a fixed I2C address is acceptable
- Can reduce wiring in modular systems
- Supports multi-digit LED display designs
- May require more specialized library support than common beginner modules
For CANABLOX-style modular systems, a CH423S-based display can be useful because the display becomes just another I2C module on the bus.
Display Size and Digit Count
The number of digits or LEDs matters. A driver that is perfect for a 4-digit module may not be the best driver for an 8-digit display or an LED matrix.
| Display Need | Good Driver Direction | Reason |
|---|---|---|
| Small 4-digit display | TM1637 | Simple, common and low-cost |
| 8-digit 7-segment display | MAX7219 or CH423S, depending on module design | Both can support larger multi-digit numeric displays in suitable circuits |
| 8x8 LED matrix | MAX7219 | Very common matrix driver with strong library support |
| Display plus buttons | TM1638 | Designed for display and key scan use |
| I2C display module in modular system | CH423S | Can use the shared I2C bus |
Brightness and Current
LED display drivers make displays easier to control, but they do not remove power limits. Bright LED displays still need enough supply current and proper design.
- Brightness setting affects current consumption
- Large displays need more current than small displays
- Multiplexed displays may have peak currents higher than average current
- Power supply voltage and module design matter
- Do not power large LED displays from weak microcontroller regulator pins
For USB-powered projects, check total display current, especially when many digits or LEDs are lit at high brightness.
Common Arduino Use Cases
| Project Type | Recommended Driver | Reason |
|---|---|---|
| Simple 4-digit clock | TM1637 | Small, simple and widely supported |
| 8-digit counter or large number display | MAX7219 or CH423S | Good for more digits than typical TM1637 modules |
| Scrolling LED matrix text | MAX7219 | Common matrix modules and libraries |
| Simple front panel with buttons | TM1638 | Buttons and display handled by one module |
| I2C modular display | CH423S | Fits naturally into I2C-based module systems |
Library Support
Library availability can decide how easy a display is to use.
- MAX7219 has many mature Arduino libraries
- TM1637 has many simple libraries for 4-digit modules
- TM1638 has libraries for display and button modules
- CH423S may require a more specific library for the exact display module
For beginner projects, MAX7219 and TM1637 are usually the easiest because examples are common. For a product or modular system, a less common driver can still be a better fit if the hardware design benefits from it.
When to Use MAX7219
- You are using an 8x8 LED matrix module
- You need an 8-digit 7-segment display
- You want strong Arduino library support
- You may want to chain multiple display modules
- You are building a scrolling text or LED matrix project
The MAX7219 is the classic choice for LED matrix modules and many 8-digit numeric displays.
When to Use TM1637
- You need a small 4-digit numeric display
- You want very simple wiring
- You are building a small clock, counter or meter
- You do not need buttons on the same driver
- You want a low-cost beginner-friendly module
The TM1637 is often the easiest driver for simple 4-digit display projects.
When to Use TM1638
- You need buttons and display on one module
- You want simple menu input
- You are building a small control panel
- You want LEDs, keys and 7-segment digits together
- You want to reduce wiring for a user interface panel
The TM1638 is best when input and output should be combined in one front-panel module.
When to Use CH423S
- You want an I2C-controlled LED display
- Your project already uses I2C heavily
- You are building a modular I2C-based system
- You need a multi-digit display with clean wiring
- You are comfortable using a module-specific library
The CH423S is a good choice when I2C integration is more important than using the most common beginner display driver.
Common Mistakes
- Choosing TM1637 for a project that needs more digits than the module provides
- Choosing MAX7219 for a simple 4-digit display where TM1637 would be easier
- Ignoring power supply current for bright LED displays
- Assuming TM1637 is normal I2C because it uses two wires
- Forgetting that display modules may have fixed addresses or fixed wiring
- Choosing a driver before deciding whether buttons are needed
Which Driver Should You Choose?
| Need | Best Choice | Reason |
|---|---|---|
| 4-digit numeric display | TM1637 | Simple, common and easy to wire |
| 8-digit numeric display | MAX7219 or CH423S | Better suited for more digits, depending on display module design |
| 8x8 LED matrix | MAX7219 | Very common and well supported for matrix modules |
| Display with buttons | TM1638 | Includes key scan support |
| I2C modular display system | CH423S | Works naturally on an I2C bus with other modules |
| Beginner LED matrix project | MAX7219 | Many examples and libraries are available |
When to Use Something Else
Sometimes a different display type or driver is better.
- Use a character LCD when text labels and menus matter more than bright LEDs
- Use OLED when a small graphic display is needed
- Use TFT LCD for color graphics and richer user interfaces
- Use addressable RGB LEDs when color effects are the main goal
- Use a GPIO expander when the project needs general I/O more than a display driver
Conclusion
MAX7219, TM1637, TM1638 and CH423S are all useful LED display driver choices, but they are best suited for different module types.
- Choose MAX7219 for LED matrices and many 8-digit 7-segment display modules.
- Choose TM1637 for simple 4-digit numeric displays.
- Choose TM1638 when the project needs display output and button input on one module.
- Choose CH423S for I2C-based modular LED display systems and display/I/O combinations.
The best driver is not always the most powerful one. It is the one that matches the display size, wiring style, required buttons, available libraries and overall system design.