Questions tagged [junction]

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Case temperature MOSFET

I am going to use a nMOSFET (NTMFS5C670NL) which will a varied power dissipation. The current going from drain to source is determined by a control signal. The maximum power dissipation for the MOSFET ...
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1 answer
60 views

Majority Charge carriers and electron holes

Suppose I have an extrinsic semiconductor made of silicon and doped with phosphorous. Now, phosphorous has one more electron than silicon. After replacing one silicon atom, and taking its place, the ...
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Schottky barrier at equilibrium

At equilibrium, the barrier for electrons to go from metal to semiconductor is higher than the barrier for electrons to go from semiconductor to metal. Shouldn't that mean there are more electrons ...
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1 answer
178 views

Why is the collector region doped?

As long as within the active region the collector-emitter junction is reverse biased, is there a purpose for which the collector must be doped? Moreover, not only that it is doped, but it is ...
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PN Junction Formation

When a PN junction is formed, free electrons from the N type diffuse into the P type material. Now books say that the same applies for holes, which diffuse from the P type material to the N type one. ...
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2 answers
126 views

What prevents the lead attached to a semiconductor from forming Shottky junction

What prevents lead attached to a piece of semiconductor (for example in BJTs and FETs) from forming a Shottky junction?
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1 answer
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Blocking voltage of diodes

What exactly is blocking voltage in relation with Metal-semiconductor junction diodes? Is it related to breakdown voltage?
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2 answers
376 views

Mosfet Thermal Resistance calculation

I went through the application notes of infineon and TI. In the datasheet on the MOSFET, there is a junction to case Thermal Resistance given. Can we use these values to calculate the power ...
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1 vote
0 answers
155 views

Calculate the Thermal Resistance (Junction to ambient) from Thermal Resistance (Junction to mounting base)

I have this MOSFET - MOSFET Datasheet I want to calculate the maximum junction temperature of the MOSFET part. I have calculated the power dissipation. In the MOSFET datasheet, there is only Thermal ...
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2 answers
278 views

Thermal Resistance, PCB Operating Temperature and PCB Self Heating

I want to understand a few terms. My Questions : What does Maximum PCB operating Temperature for a PCB in general depend upon? Maximum PCB Operating temperature depends on Tg (Glass Transition ...
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3-terminals magnetic tunnel junction

I was wondering if a 3 terminals magnetic tunnel junction can be implemented, as in the Figure. On the bottom I have a normal metal (NM), on the top a magnetic junction (FM = ferromagnet) and I can ...
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1 answer
425 views

Thermal resistance Junction - Maximum Power dissipation

I want to understand the real meaning of the parameter 'Thermal Resistance Junction to Air (°C/W) to calculate the power dissipation. So for example if the value of this parameter is 250°C/W, should I ...
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3 answers
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Failed to plot junction capacitance versus reverse voltage in LTspice

The 1N4001 diode's junction capacitance versus reverse voltage plot is given as follows: I guess to measure this capacitance they applied 1MHz 50mV pk-pk sine wave signal as reverse biased and varied ...
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4 answers
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1N5822 schottky diode heatsinking

Is the cathode for schottky diode hotter than the anode, as is common for most diodes, or is it reverse polarity? A schottky is a metal-semiconductor junction, with the metal at the anode. So it ...
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1 answer
98 views

Li-Ion Battery Charging Board Temprature (Junction Temp)

I'm looking for a little help with a simple battery charging project. I've bought a pack of cheap USB charging boards on ebay (link) with the intent of using one to charge a small Li-Ion battery. ...
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2 answers
6k views

What does it mean bipolar or unipolar junction in a transistor?

I can't find the definition of unipolar and bipolar junction in a transistor, for example BJTs has a bipolar junction and MOS-FET has a unipolar junction, what does it mean unipolar and bipolar ...
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3 votes
2 answers
160 views

Evaluating junction temperature from thermal imaging data

I have a SOD-123F diode through which a current of ~1A flows, creating a forward voltage drop of around 300mV. The datasheet does not specify Rjc but gives Rja = 200 C/W and Rjl = 70 C/W for a 10cm x ...
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631 views

Collector-Emitter short but not Base-Emitter

I have a power amp that blew the pair of transistors(2SD1047 and 2SB817) at the output. The positive side 1047 is totally shorted, all junctions, the negative side 817 is only shorted Collector-...
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1 vote
2 answers
165 views

Relationship between junction area and voltage in forward biasing

What is the relationship between junction area and voltage in forward biasing? My book said that the voltage to establish forward biasing increases with decreasing of junction area. Why? EDIT: The ...
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3 votes
1 answer
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Why can't current go through two voltage source junction?

I crossed out the middle because it felt like it wouldn't make sense. (Mostly because i felt like conservation of current was violated.) But im not sure why it wont go through at that particular ...
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1 vote
2 answers
935 views

Why don't the minority carriers combine with the majority carriers in a PN junction?

I wanted to start this question by giving my understanding of the make up of a PN junction. I do this so that you can pick me up on anything that I may be getting wrong in the lead up to my question. ...
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1 vote
2 answers
375 views

Is there any junction, or branch element for jumper cables?

I would like to create circuits using jumper cables. I have male-female, male-male, and female-female jumper cables too. But I cant find any branching cable on ebay. What should I use, to create ...
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2 votes
1 answer
1k views

Calculating maximum power dissipation based on contact area between two metal conductors

I am trying to figure out how to properly calculate the minimum contact surface area based on the maximum required power dissipation. Let me explain.. I am creating a custom semi-circular metal tab ...
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  • 83
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1 answer
123 views

IC Thermal shutdown recovery time

Many RS485 transceiver chips have a thermal shutdown when the junction exceeds 150C. Typically they switch back on once the junction temperature drops 15 degrees. How long does that typically take? ...
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8 votes
5 answers
3k views

Where is the cold junction on the commercial thermocouples?

According to all textbooks and articles, a thermocouple must have a cold junction somewhere on the middle of it. But none of the commercial products have a middle point or a marked spot for ...
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