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Questions tagged [body-diode]

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6
votes
2answers
481 views

Can a MOSFET be used to switch between two supply voltages?

My goal is to programmatically switch between supply voltages (3.3V and ~2.6V) for a load. The 2.6V level doesn't need to be exact, +/- 0.2V is OK. I created the following circuit, which uses my MCU's ...
0
votes
1answer
34 views

MOSFET - Body Diode protection

I want to build the cricuit like on the image below: V1 - Is a 14S LiPo battery(there would be fuse in real life between positive battery terminal and "BATTERY+" M1 - PMOS acting as a load ...
0
votes
0answers
252 views

MOSFET as bypass diodes in series of solar cells

I am building a small solar system of 5 solar cells in series (each about 5V 500mA in full load, total 25V 500mA) and want to maximize efficiency in case one cell is shaded. Traditionally there are ...
1
vote
1answer
109 views

Why do some analog circuits use a FET with shorted drain and source?

Why do some analog circuits use a FET with shorted drain and source? Depending of the type of FET, it may either act as a capacitor or a diode? It each case, why not just use a cap or a diode? Below ...
0
votes
1answer
82 views

Bidirectional level translator using N channel MOSFET

I'm using a n channel MOSFETa bidirectional level translator. The case when the body diode conducts the source end will be literally 0V or forward voltage of body diode, so the difference in voltage ...
1
vote
1answer
242 views

Freewheeling diode position [duplicate]

I have a pneumatic solenoid valve switching from IRF830 MOSFET. Solenoid valve connected to MOSFET by 2-3 feet long wire. It's necessary to use a freewheeling diode for this? What is the most ...
0
votes
2answers
98 views

Forward diode characteristics not starting from zero Ampere

Why the current is not starting from zero, whats the diode characteristic when current is near zero? Reading the datasheet for N-channel 60V MOSFET, I encountered this source-drain characteristic of ...
1
vote
0answers
105 views

NMOS bidirectional variable resistor: How to increase body diode barrier potential?

I want to use an NMOS as a variable input resistor to an inverting amplifier. The source is connected to virtual ground and the drain is connected to the input. I need to accomodate both positive and ...
16
votes
3answers
10k views

How should I understand the intrinsic body diode inside a MOSFET?

I know there is an intrinsic body diode inside all the MOSFETs, but I'm confused about the reason why it's there. I've searched the articles but can't find a good explanation for it. Can anyone use ...
2
votes
2answers
3k views

ORing mosfet controller with ability to switch off the load

My system is powered from a wall adapter and backup SLA battery. simulate this circuit – Schematic created using CircuitLab Since the voltage of the wall adapter is higher than the SLA, I have ...
0
votes
0answers
170 views

How can I map Body Diode datasheet params to simulink N-MOSFET model?

I would be interested on including the body diode effect of a NMOS transistor into the N-Mosfet that Simspace includes for electronics. However, the parameters that the Body diode in Matlab requires ...
2
votes
1answer
689 views

Turning an NMOS with substrate terminal into a PMOS

Some NMOS's come with a substrate/bulk/body terminal so the "Source Voltage" referred to in literature then Substrate Voltage. Say then we short the gate to the drain and have the substrate take the ...
4
votes
2answers
2k views

I need some help understanding overshoot and ringing in MOSFET half bridges

From FDA75N28 datasheet: What I am having difficulty understanding are the reasons behind overshoot and ringing in V_DS. Now, to what I already know: The current that passes in an inductor cannot ...
2
votes
3answers
2k views

Where does the MOSFET body diode come from?

Where does the body diode in a MOSFET come from? I understand that its built in and an intrinsic part of the MOSFET. All illustrations of a MOSFET that I've seen depict the structure as two diodes ...
6
votes
5answers
2k views

MOSFET with *actual pin* for body

I have always thought that MOSFETs have four pins [see wikipedia], one of them connected to the body (i.e. substrate). However, when trying to order some, I have been completely unable to find any ...
2
votes
0answers
234 views

Extra Shottky Flyback Diodes on FET-based BLDC Motor Driver? [duplicate]

TL;DR: I have a FET-based BLDC motor driver design, and I need to decide whether to add discrete Shottky diodes in parallel with each FET for reliable and long-lived operation in an automotive-like ...
1
vote
1answer
2k views

Body Diode of a MOSFET

So for some MOSFETs, specially with Power MOSFETs, the body diode is a flyback diode that (as far as aI can tell) can be conveniently added to the MOSFET's bulk as there already PN junctions (correct ...
0
votes
1answer
1k views

Substrate Connection when driving a Bi-Directional Switch

I am very confused about the way the below circuit functions. Below is an excerpt from a research paper which shows two NMOS transistors connected such that the body diodes face each other back to ...
3
votes
2answers
2k views

Use of MOSFETs body diode

I have an N-MOSFET array IC and I don't need to use all of them, but I do need to use a diode. Is it OK to use the body diode of one of the MOSFETs as a regular diode to decrease component count and ...
3
votes
5answers
2k views

Replacing a Switch and Avoiding body diode conduction

I am trying to design a replacement for a 2:1 switch using FETs, which would be really easy if I didn't have to concern myself with the body diodes that are present on PMOS transistors. My scenario ...