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What is the difference between common cathode and common anode displays

As a leading LED manufacturer, our main products include THT numeric display, SMD numeric display, dot matrix, bar graph, light-emitting diodes (LEDs), SMD, Flux, high-power LEDs, and modules. These products are widely used in various applications such as home appliances, mobile phones, road traffic, urban lighting, energy-saving lighting, and many others. One of our key strengths is our state-of-the-art facility, which boasts a 12000㎡ dust-free and antistatic standard workshop. This ensures that our manufacturing process is of the highest quality, resulting in superior products that meet the highest industry standards. 

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In addition to these certifications, our UV sterilization technology has passed the photobiological safety test requirements specified by EN62471, guaranteeing its effectiveness and safety. We have also met the European and American LM-80life test requirements, further proving the reliability and durability of our products. Moreover, we are proud to mention that our products fully comply with the current international RoHS and REACH regulations, ensuring environmental friendliness and reducing potential health hazards.



1.What is the difference between common cathode and common anode displays?
2.Can the display be dimmed?
3.What are the dimensions of a 2 digit 7 segment LED display?
4.Is it possible to connect multiple displays together?
5.What is the maximum current rating for the display?
6.How to calculate the current limiting resistor for the display?
7.Can the display be controlled by a microcontroller?
8.How many segments does a 2 digit 7 segment LED display have?
9.Can the display be used for numerical and alphabetical characters?
10.Are there any size variations available?

1.What is the difference between common cathode and common anode displays?

Common cathode and common anode displays are two types of electronic displays used in digital devices. The main difference between them lies in the way they are wired and how they operate. 1. Wiring: In a common cathode display, all the cathodes of the individual LEDs are connected together and to the ground, while in a common anode display, all the anodes of the individual LEDs are connected together and to the positive supply. 2. Operation: In a common cathode display, the cathodes are turned on by applying a positive voltage to the anodes, while in a common anode display, the anodes are turned on by applying a negative voltage to the cathodes. 3. Voltage polarity: In a common cathode display, the voltage applied to the anodes is positive, while in a common anode display, the voltage applied to the cathodes is negative. 4. LED activation: In a common cathode display, the LEDs are activated by grounding the cathode, while in a common anode display, the LEDs are activated by applying a positive voltage to the anode. 5. Driving circuit: The driving circuit for a common cathode display is simpler as it only needs to sink current, while the driving circuit for a common anode display needs to source current. 6. Compatibility: Common cathode displays are compatible with NPN transistors, while common anode displays are compatible with PNP transistors. 7. Display brightness: Common cathode displays tend to be brighter than common anode displays as they can handle higher currents. In summary, the main difference between common cathode and common anode displays is the way they are wired and how they are activated. Both types have their advantages and disadvantages, and the choice between them depends on the specific application and the driving circuit used.

2.Can the display be dimmed?

It depends on the specific display and device. Some displays have a built-in dimming feature that allows the user to adjust the brightness, while others may not have this capability. Additionally, some devices may have a setting that allows the user to dim the display, while others may not. It is best to consult the user manual or settings of the specific device to determine if the display can be dimmed.

3.What are the dimensions of a 2 digit 7 segment LED display?

The dimensions of a 2 digit 7 segment LED display can vary depending on the manufacturer and model, but a common size is approximately 0.8 inches (20mm) in height and 0.6 inches (15mm) in width for each digit. The overall dimensions of the display may also include additional space for the circuit board and mounting hardware.

4.Is it possible to connect multiple displays together?

Yes, it is possible to connect multiple displays together. This can be done by using a graphics card with multiple display ports, a display splitter, or by daisy-chaining displays using DisplayPort or Thunderbolt technology.

5.What is the maximum current rating for the display?

The maximum current rating for a display can vary depending on the specific model and manufacturer. It is important to consult the product specifications or contact the manufacturer for the exact maximum current rating.

6.How to calculate the current limiting resistor for the display?

To calculate the current limiting resistor for a display, you will need to know the forward voltage (Vf) and forward current (If) of the display, as well as the supply voltage (Vs) and the desired current (Id) for the display. The formula for calculating the current limiting resistor is: R = (Vs - Vf) / Id Where: R = current limiting resistor (in ohms) Vs = supply voltage (in volts) Vf = forward voltage of the display (in volts) Id = desired current for the display (in amps) For example, if you have a display with a forward voltage of 2.5V and a forward current of 20mA, and you are using a 5V supply with a desired current of 10mA, the calculation would be: R = (5V - 2.5V) / 0.01A R = 250 ohms In this case, you would need a 250 ohm resistor to limit the current to 10mA for the display. It is important to note that the calculated resistor value should be rounded up to the nearest standard resistor value. In this case, a 270 ohm resistor would be used. It is also important to consider the power rating of the resistor. The power rating should be equal to or greater than the calculated power dissipation, which can be calculated using the formula: P = (Vs - Vf) * Id Where: P = power dissipation (in watts) Vs = supply voltage (in volts) Vf = forward voltage of the display (in volts) Id = desired current for the display (in amps) In the example above, the power dissipation would be: P = (5V - 2.5V) * 0.01A P = 0.025 watts Therefore, a resistor with a power rating of at least 0.025 watts should be used in this circuit.

7.Can the display be controlled by a microcontroller?

Yes, the display can be controlled by a microcontroller. The microcontroller can send commands and data to the display through a communication interface such as SPI, I2C, or UART. The display will then interpret the commands and data to update its pixels accordingly.

8.How many segments does a 2 digit 7 segment LED display have?

A 2 digit 7 segment LED display has 14 segments. Each digit has 7 segments, and there are 2 digits, so 7 x 2 = 14.

9.Can the display be used for numerical and alphabetical characters?

Yes, the display can be used for both numerical and alphabetical characters. Most displays are capable of displaying both numbers and letters, and can switch between the two as needed. Some displays may also have the ability to display special characters and symbols.

10.Are there any size variations available?

Yes, there are typically multiple size variations available for most products. The specific sizes available will depend on the product and the retailer or manufacturer selling it. It is best to check the product listing or contact the seller directly to inquire about available sizes.