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Uc3843s: Pin Configuration, Features, and Applications

You have probably come across numerous integrated circuits, each suited for various applications. Among them is the uc3843s IC which is essential for convertor purposes.

Our article will delve into the basics of its current mode control, the pinout, and other vital features.

Thus, let's direct you through all you need to know about this IC.  


What is uc3843s?

An electronic printed circuit board with many electrical components

Figure 1: An electronic printed circuit board with many electrical components


It is primarily a converter device that operates as a current PWM controller. It is characterized by having a fixed frequency. Note, we're referring to it as a converter, as you'll typically find it in DC-DC converter circuits. Also, you'll find it in a buck converter.  

uc3843s Pin Configuration

Figure 2: An 8 Pin IC


The below gives the pin configuration of the 8- pin uc3843. Note that there are also 16-pin and 20-pin packages of the same IC. For converter purposes, you can use either of the three. But in our case, we're interested in the 8-pin one.


uc3843s Features and Specifications

Integrated Circuits on a Circuit Board

Figure 3: Integrated Circuits on a Circuit Board



uc3843s Equivalents

Computer microcircuit board

Figure 4: Computer microcircuit board


The equivalent of the uc3843 is the UC3842. In addition, you can use the following ICs as alternatives to the us3843 in voltage regulators:

  • UC2842
  • UC3844
  • SG2524

In the voltage mode control mode, they'll be as effective as the uc3843s.  

How to use uc3843s

Chip close-up of an integrated circuit.

Figure 5: Chip close-up of an integrated circuit.


The IC is useful in performing complex tasks in a boost converter circuit. However, its working principle is relatively straightforward. Also, you will not require several significant components in a sample application circuit.

During use, of importance is considering the necessary precautions. For instance, note that the IC features an under-voltage protection property. Thus, after joining the circuit's discrete components, ensure you set the operating voltage between 7V and 8.2V.

Also, note that the IC's output pin is linked to the power switch's gate driver circuit. Remember that the output pin can deliver a current source of up to 1A. Thus, you'll require a current limiting resistor in the course.

Also, the circuit has a shunt resistor which will aid in monitoring the change of current. Consequently, the resulting difference voltage on the shunt is fed to the IC's feedback pin.

Besides, there's an internal oscillator in the IC. You can configure it by connecting the proper current sense resistor and capacitor. The preferable choice that you'll find in the UC3943 datasheet is a capacitance of between 470pf to 4.7nf. For the parallel resistors, you can have resistors with a resistance of 5k to 100k.  

uc3843s Real-Life Applications

A green circuit board with some chipsets

Figure 6: A green circuit board with some chipsets


  • Useful in a battery drain circuit to control input noises.
  • Also relevant in switch mode supplies (SMPS) Circuits.
  • Essential in load machines for precise duty cycle control and load regulation.
  • Essential in switching regulators featuring varying polarities.
  • In electronic power supply lines for load regulation
  • Lastly, in transformers that have DC-DC converter circuits



Now you have it all. IC's are essential for effecting several modes of control in electronic circuits. For electronic enthusiasts, finding a suitable IC for use in converters is without a doubt a key breakthrough. For all your converter applications, consider this model. Also, you may have several questions on its other dimensions. Reach out to us, and we'll always give you the way forward.