Transistor operation mode is can easily be determined by using mathematical equations. Don’t worry; these are not difficult equations. There are three operation modes to operate the transistor. These are cut-off, saturation and linear. In cut-off, the transistor is simply not conducting; so it is not a problem to send the transistor in this region. You can simply do that

Continue reading# Year: 2015

## Heat Sink Thermal Resistance Calculation Easy Explanation

For power devices like power MOSFETs, power BJT and power diodes, heat sink is very important to provide thermal relief. From the name itself, it will sink the heat from the power devices and help controls the temperature in the safe zone. In this article I will discuss heat sink thermal resistance calculation. For a system with forced cooling method,

Continue reading## MOSFET RDSon Temperature Coefficient Usage and Interpretation

MOSFET RDSon temperature coefficient is positive. Meaning, it will increase with increasing temperature. In this article I will discuss and interpret MOSFET RDSon temperature coefficient that is often given in the form of graph in datasheets like below. Datasheets may also provide actual RDSon data with respect to junction temperature instead of the coefficient like below. Datasheets also provides tabular

Continue reading## Worst Case Analysis and Tolerance Simulation Using LTSpice

I believe there are few ways to perform worst case analysis and tolerance simulation using LTSpice. In this article, I will be sharing my own technique. This can be an easier approach and at the same time you will have your Monte Carlo analysis and simulations already. Basically, I will be making use of the Monte Carlo run to come

Continue reading## NPN Transistor Biasing Tool and Checker in Excel

In this article I will discuss the feature of the NPN transistor biasing tool and checker in excel that I made. This is very useful for design engineers that don’t want to perform simulations and long manual calculations. This NPN transistor biasing tool and checker is also very useful for students to verify if their computations on their assignments are

Continue reading## Sizing the Inductor of Buck Converter and Setting its Operation

One of the most important parts of a buck converter is the inductor. Sizing the inductor of buck converter and setting its operation mode makes the converter function correctly. The shape and the magnitude of current of the inductor are dictated by the inductance of the inductor itself. Therefore choosing the right inductor value is very important. Sizing the inductor

Continue reading## Buck Converter Duty Cycle Derivation

In this article I will share to you the methods I used in buck converter duty cycle derivation. We will consider the ideal and the real scenarios. In ideal buck converter duty cycle derivation, you don’t need to consider the voltage drops of the switching element and catch diode. On the other hand, in real buck converter duty cycle derivation,

Continue reading## Common Application of Optocoupler in Today’s Electronic Circuits

The most common application of Optocoupler is signal isolation. It provides complete isolation because its input side is not electrically connected to the output side. Its input side is a light source which is commonly a LED, while the secondary side is a photo transistor. A photo transistor is also a transistor but without a base current. The absence of

Continue reading## Disadvantage of using Optocoupler with Low CTR for Switch Operation

In optocoupler, CTR stands for current transfer ratio. This is comparable to the current gain beta in BJT. This is the most important parameters of an optocoupler to function normally. There are several factors that affect the CTR, read here. In this article we are going to focus what is the disadvantage of using Optocoupler with low CTR particularly in

Continue reading## Optocoupler Device CTR and Circuit CTR Explained

When you already heard about Optocoupler devices, you may be heard also about CTR. CTR stands for current transfer ratio. In bipolar junction transistor this is the so called current gain or simply beta. It is the ratio of the collector to forward current of an Optocoupler. In circuit design involving optocoupler, you may be dealing with the device CTR

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