Buck converter using NE555 and N-Channel MOSFET
Sometimes making a high amp regulator become very complex using linear regulator ICs. But using a buck converter, this can be very easy if the circuit work is simplified. Especially for motor-type loads. In this article, we will make a simple motor regulator using buck converter utilizing N-Channel MOSFET and NE555 ic. So let’s start!
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In the previous article, we have learned about the basic operation of buck converter using N-Channel MOSFET. For basics, you should read that before reading this article.
The basic buck converter use P-Channel MOSFET which is little complex to use without proper gate driving IC. But if the configuration is modified a little, it become more easier to handle. Here the basic circuit is this:
This circuit can be further modified to a practical one. But first, we need to replace the clock source with a circuit. Here, the most common and easiest timer IC NE555 can be used.
NE555 as PWM generator:
NE555 timer IC can be used in different modes. One of those is the PWM generator. You can read these Application note1, Application note2 to know more about NE555 timer IC. There is an article on this you can read it too.
Also there is a simulation video for better understanding:
Adding this PWM generator to our buck converter:
Now we can use this PWM generation circuit to out buck converter circuit.
Now the circuit is ready for operation. We used 12V as input and NE555 is directly supplied 12V. So there is no need to use any extra opto-coupler P817C as the output is over 10V from NE555.
The circuit is also designed in PCB. Here is the PCB layout:
You can print this PCB from our PCB partner: JLCPCB.com
After making the PCB, I tested the circuit with lamp. Here is the test result:
This circuit is very simple and useful for small to medium inductive and resistive loads only. Where linear regulators are not suitable this converter can be used alternatively. Comparing with the linear one, the conversion loss is pretty low. A small heatsink is enough for normal loads, but I recommend using a suitable heatsink with the MOSFET for long-lasting.
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