40 x 4 LCD Character Display Modules explained

When your display needs to be readable at a distance, 40 x 4 character display modules are an excellent choice for: alarm systems, thermostats, and industrial freezers.

They come in a variety of sizes.

The larger the glass size, the larger the character size to make it easier from a distance.

Power requirements:

The larger the size of glass, the more power required to drive. Most 40×4 character display modules can operate for as little as 2mA when the LED backlight is off.

Backlight brightness:

It is possible to adjust the backlight’s brightness of the backlight to meet the environment it will be operating in. Low brightness for aviation and automotive, high brightness for outdoor scales and construction equipment.

Note: increasing backlight brightness will decrease the display’s half-life.

Half-life is the amount of time, in hours, before the LED is 50% as bright as when first turned on. This is not the amount of time before it burns out.

Backlight options:

For low power needs, all character LCDS are available with no backlight and include a reflective polarizer for sunlight readability.

LED backlights or side lights are available for nighttime readability and can draw between 15mA to 90mA current.

A partial list of available backlight colors includes: Yellow/Green, White, Blue, Pure-Green, Red and RGB (Red, Green, Blue)

It’s best to stay clear of EL backlights on new product designs due to their short half-life (3K hours) and the AC signal noise they generate.

Operating voltage:

Smaller sized displays will operate at 3.3V or 5V (5V is best for colder temperatures). Choose the 5V option if your product is not battery powered or used outdoors. There is no difference in cost or lead-time.


Currently, the Sitronix ST7066 controller IC is the default IC chip and offers a 6800 4/8-bit parallel interface. The ST7066 is an Industry-standard HD44780 compatible controller.

Character LCD interface:

The standard interface is 8 bit parallel. Characters displays are available with a SPI interface to reduce the number of I/O’s (In/Outs) needed to drive the display. SPI is more expensive than parallel due to the additional chip required.

Temperature Range:

Standard operating temperate ranges from -20℃ to +70℃; with storage temperatures ranging from -30℃ to +80℃.

Need it to operate at colder temperatures?

It is possible to custom build a character LCD to include several ¼ watt resistors attached to the PCB that will generate enough heat to keep the display operational.

Available languages/Fonts:

Character LCDs are available in a variety of languages including: German, French, Japanese and others.

Note: Japanese and Chinese fonts require a 16×16 dot matrix character.

There is no MOQ for English font character displays in stock. Same day shipping is possible.