hybridfree/eevblog-posts huggingface dataset:
Free Mosfet Model Maker Excel - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: November 19, 2024, 09:59:44 pm
content: I present a Microsoft Excel spreadsheet that can be used to make a SPICE model from the part's datasheet. In a previous video, I used Mathcad to make my MOSFET SPICE model, however, I no longer have access to Mathcad and Excel is a great alternative. I show how to use the ID vs VDS family of curve to extract the DC characteristic and the parasitic capacitance to get the AC characteristic and then show how to verify with SPICE. Please keep in mind that this is a first order model. I have successfully used this procedure to model devices that have no SPICE model and have gotten good results. If you find this video useful, please subscribe and share. Request for the Excel spreadsheet can be sent to rbola35618@aol.com.I have attached the file. Please change the suffix from .TXT to .xlsm

author: Benta
author_rank: Super Contributor
timestamp: November 19, 2024, 10:22:03 pm
content: Did you try GNU Octave?It's a free, open-source alternative to MatLab. Not as easy to use as MathCad, but prolly easier than Excel.

author: Zero999
author_rank: Super Contributor
timestamp: November 21, 2024, 09:22:36 am
content: Quote from: rbola35618 on November 19, 2024, 09:59:44 pmI suggest you consider removing your email, as it might attract spam.Is there any reason why you don't want to post it as an attachment? Either zip it, or save it as ods and you can upload it by clicking onAttachments and other options.

author: rbola35618
author_rank: Frequent Contributor
timestamp: November 21, 2024, 03:32:51 pm
content: I tried to upload the excel file but it won't allow excell file to be loaded. I changed the extension to .TXT. Hopefuly this will work if you rename the extension back to .xslm

author: Zero999
author_rank: Super Contributor
timestamp: November 21, 2024, 04:35:26 pm
content: Quote from: rbola35618 on November 21, 2024, 03:32:51 pmThat's because the forum doesn't support files with the extension .xlsmAn alternative to renaming it is to create a zip file, using an archiving utility, such as 7-Zip or the one built in to Windows, which saves the person downloading it from renaming it.

author: rbola35618
author_rank: Frequent Contributor
timestamp: November 21, 2024, 08:17:06 pm
content: Thank you!!!!!!

author: TimFox
author_rank: Super Contributor
timestamp: November 21, 2024, 08:45:18 pm
content: The macro-enabled version of Excel files is .xlsm, not .xslmhttps://www.omnisecu.com/excel/basics/difference-between-xls-xlsx-xlsm-file-formats.php

author: Zero999
author_rank: Super Contributor
timestamp: November 21, 2024, 09:44:13 pm
content: Quote from: TimFox on November 21, 2024, 08:45:18 pmIt was probably a typo and I don't know any better, since I'm not an MS Office user. I did find it odd that it didn't automaticaly open with LibreOffice on Linux when I clicked on it, but that sort of thing is common.
MOSFET or other switching circuit to disconnect two separate grounds - Page 1
Forum section: electronics / projects

author: Finndersen
author_rank: Newbie
timestamp: May 19, 2016, 08:00:46 am
content: Ok so I have a project where I'm powering a Rpi with either external DC supply or a USB power battery bank thing.The USB power bank has a charging input and power output.It's done in some strange way where the input and output grounds are disconnected from each other when the battery pack is not in operation (either charging or supplying power)When it is in operation, the grounds be come connected.However, if the input and output ground are connected together while the pack is meant to be off, it puts it into some strange semi-on state where it has 3.8V at output terminal, causing an LED to come on and the Rpi to be partially powered but not work. Basically non-ideal.When connected in the shown configuration, the Rpi becomes a bridge connecting the battery pack output ground to input ground, which causes this problem.The simplest solution is to have a physical switch between external DC supply and battery pack charging input, which is only turned on when external supply is powered in order to charge battery.The switch could also be turned on when the battery pack is active and supplying power to the GPIO input of the Rpi. There is an internal ideal diode in the Rpi which will prevent the battery pack charging itself.But the connection from output ground to input ground must be severed when the system is meant to be completely off.I've played around with some N and P channel MOSFETS but havent found a configuration which works.For example with a simple N-channel MOSFET switch, with battery input ground connected to Source, Rpi output ground to Drain, and external DC positive to Gate, the battery input ground must be tied to external supply ground in order for the positive VGS reference to work.Can anyone help? Having no physical switch would be idealCheers
MOSFET over heating at lower than expected load currents  - Page 1
Forum section: electronics / projects

author: ReadyEdi
author_rank: Newbie
timestamp: December 10, 2017, 01:48:20 pm
content: Hello there,I'm testing a new switch method for my battery cut off circuit and when testing the FQP27P06https://www.sparkfun.com/datasheets/Components/General/FQP27P06.pdfP channel mosfet at 12V at the source and 0V at the input it generates quite alot of heat without a heat sink at 5A and when measuring the Vds voltage and multi pling it by the current I get around 2.15Ohm which is way above what is being said in the datasheet.Why is that?Thanks for helping

author: danadak
author_rank: Super Contributor
timestamp: December 10, 2017, 02:13:28 pm
content: At Vgs = 12 V you are getting somewhere around .07 Rdson,so P = 52x .07 = ~ 1.75 W, so part w/o a heat sinkwould be quite hot, burn your pinkie.Tj-c is ~ 62 C/W, so case would fry eggs.Regards, Dana.

author: ReadyEdi
author_rank: Newbie
timestamp: December 10, 2017, 08:25:12 pm
content: Hi thanks for the replay regarging that do you maybe know of any other better component to suit that need that doesn't require a heat sink for long continues operations?

author: Freelander
author_rank: Regular Contributor
timestamp: December 10, 2017, 08:43:31 pm
content: You can get lower RDSon devices but it is not too bad to start with. I presume this is fully on ? - not pwm'd etc ?, so not operating in the linear region at all. If the gate is at 0v and the source at 12v then you will have the device fully on.You can put multiple devices in parallel, it is a method we have used in various devices many times. Worth putting a low value gate resistor for each fet - 100r 'ish. that will work fine.
MOSFET pull down in linear region - Page 1
Forum section: electronics / projects

author: matt111
author_rank: Newbie
timestamp: January 17, 2018, 06:51:28 pm
content: I have a current sense IC powered directly from a battery. I want the current sense IC to be in the shutdown state when the 3.3V power supply is disabled.I have added a dual N channel MOSFET circuit (see attachments) to achieve a pull down on the shut down pin (active low and internally pulled high) when the3.3V supply is not present. The circuit seems to work in LTspice but I am concerned about one of the MOSFETS operating in the linear region. (VDS < VGS - VT)Is it safe to operate the MOSFET in this configuration or is there anything I'm missing that is considered bad design?

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 17, 2018, 08:11:13 pm
content: No, there is no issue with a MOSFET operating in the linear region. It is perfectly fine.You are driving the gate with 30 volts. Make sure that the MOSFET you are using will support a VGS=30VBTW, your notation about M2 says that it operates in Sat. It appears to me that it too operates in the linear region...which is OK!You may be a little confused about the terminology. At a basic level, a MOSFET is either ON or OFF. When OFF, there are no "regions" per say. When it is ON, it can be in linear or saturation region.

author: Benta
author_rank: Super Contributor
timestamp: January 17, 2018, 08:24:13 pm
content: R1 and R2 are way too high. Check the datasheet for drain-source leakage current on your MOSFETs, you'll see what I mean.
Mosfet RC snubber for a buck boost controller - Page 1
Forum section: electronics / projects

author: Rainman
author_rank: Newbie
timestamp: February 26, 2020, 11:29:43 pm
content: Hello guys,I have a buck boost regulator LT8390 from Analog/Linear running at 12V/8A output with a great amonunt of switching oscillations on the output. I want to add an RC snubber circuit to dampen the oscillations and have looked at a demo circuit schematic showing how it could be done. I have also read some theory about the subject.Here is a link to the demo board schematic:https://www.analog.com/media/en/technical-documentation/eval-board-schematic/710-DC2825A_REV02_PCA_SCHEMATIC.pdfFrom the demo schematics it is suggested to have RC snubber across mosfets M1 and M3. I can agree on the M3 snubber for boost mode operation, but other litterature is suggesting to have the snubber for buck mode operation placed across M2 and not M1 as the schematic is showing.Anyone out there who has designed a similar thing and knows which mosfets to place the snubber across? I don’t have any footprints for snubber components om my current PCB so trial/testing is not so easy at the moment.Best regards,Rainman

author: thm_w
author_rank: Super Contributor
timestamp: February 28, 2020, 01:32:47 am
content: What is the switching frequency, 150-650kHz fixed or spread spectrum?What are the switching oscillations on the output, noise, ripple? It may be necessary for an output filter instead.Are they excessive in boost mode, in buck mode, or both?Trial and testing will be necessary, solder components to the PCB, you may have to be creative and scrape off solder mask, etc.Putting the snubber across M2 or M1 should not make much difference. You can test it for yourself. The DC voltage across the snubber may differ though.
Mosfet RDS and heat output losses (LED DIMMING) - Page 1
Forum section: electronics / projects

author: 24602
author_rank: Contributor
timestamp: February 27, 2023, 03:56:22 am
content: Hey AllDesigning a LED Dimmer, second guessing my mosfet selectionMy design has a VND7NV04TR-E Mosfethttps://www.digikey.com.au/en/products/detail/stmicroelectronics/VND7NV04TR-E/1665403Comparing to another design using a AON7244https://www.digikey.com.au/en/products/detail/alpha-omega-semiconductor-inc/AON7244/3061083My design generates significant heat from the mosfets, whilst the AON7244 is just slightly warm to the touch.Is that due to a RDS on of 60mOhms compared to the AON7244 8.5mOhm?So I'm thinking of replacing the VND7NV04TR-E with a AOD4184Ahttps://www.digikey.com.au/en/products/detail/alpha-omega-semiconductor-inc/AOD4184A/2353886Am I correct that this will improve the heat output and losses of the VND7NV04TR-E I'm currently using?(Testing at 24V 5A (120W)

author: georges80
author_rank: Frequent Contributor
timestamp: February 27, 2023, 04:00:03 am
content: Dimming how? PWM or what? Some details will help provide some answers versus questions...Power loss = I x I x R

author: 24602
author_rank: Contributor
timestamp: February 27, 2023, 04:01:56 am
content: Yes via PWM - Device has selectable PWM frequency from 70hz to 40Khz

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: February 28, 2023, 12:31:46 am
content: Just on paper, at 100% duty cycle that ST MOSFET is dissipating 1.5 W of heat due to the Rds alone. You can characterise other potential contributors such as gate charge or Vgs but you won't improve on this. If the Alpha & Omega part at similar cost saves you a heatsink, it's a no-brainer.
MOSFET rectifying circuit - Page 1
Forum section: electronics / projects

author: raff5184
author_rank: Regular Contributor
timestamp: December 01, 2020, 02:15:13 pm
content: Hi all,I tried to make the MOSFET rectifier in the attached image. The input is a 1MHz sinusoid varying from 5Vpp to 20Vpp coming from a signal generator followed by amplifier.The circuit for some reason doesn't work. This is what I observed:the moment I connect the input to the circuit, the input sinusoid gets "randomly" shifted up or down, and/or its amplitude becomes much smaller, the output on the other hand is always 0 Vdc. In a couple of occasions, the input wasn't shifted and I could see the rectified output but it lasted for few seconds, as it was unstable, and then the same behavior.I tried two combinations of MOSFETS:A) Two N-ch DMN65D8L and two P-ch DMP3098LDMB) Two N-ch XP231N02013R-G and two P-ch ZXMP3A17E6TAMight it be because of some imbalance in the circuit, like the current flows only in one side and not in the other? Maybe because the FETs are not exactly of the same series? And so it can't switch properly?

author: klr5205
author_rank: Regular Contributor
timestamp: December 01, 2020, 02:36:11 pm
content: Difference in turn-on time causing shoot-through perhaps?

author: Ice-Tea
author_rank: Super Contributor
timestamp: December 01, 2020, 02:39:52 pm
content: Probing technique? Very easy to short out your circuit with a scope like this. Recommended viewing material:

author: raff5184
author_rank: Regular Contributor
timestamp: December 01, 2020, 02:43:10 pm
content: I eventually removed the scope probes and I only have an amperometer in series to the load (a capacitor)

author: Zero999
author_rank: Super Contributor
timestamp: December 01, 2020, 03:20:15 pm
content: Quote from: raff5184 on December 01, 2020, 02:43:10 pmThere's your problem: that circuit is unsuitable for capacitive loads.

author: raff5184
author_rank: Regular Contributor
timestamp: December 01, 2020, 03:59:07 pm
content: that was a quick solutionJust out of curiosity and to learn, why is it?

author: Zero999
author_rank: Super Contributor
timestamp: December 01, 2020, 06:49:10 pm
content: Quote from: raff5184 on December 01, 2020, 03:59:07 pmI suggest you try to figure it out for yourself. Assume the MOSFETs have a threshold voltage of 2V and they have a body diode, in reverse parallel with the drain and source. Note the gate-source voltages, when the sine wave is at the peak positive and negative extents, without a capacitor on the output. Now do the same, with the capacitor on the out. If that doesn't help, try simulating it. If you don't want to install a program, such as LTSpcie, then use the online simulator linked below:https://www.falstad.com/circuit/To use a MOSFET regulator, to drive a capacitive load, add a Shotky diode to the output, or use a MOSFET bridge rectifier controller IC.

author: raff5184
author_rank: Regular Contributor
timestamp: December 01, 2020, 07:30:36 pm
content: Great Zero,will try that, thanks
MOSFET replacement - Page 1
Forum section: electronics / projects

author: soubitos
author_rank: Frequent Contributor
timestamp: January 22, 2018, 02:46:37 pm
content: What would you suggest as replacement for a P channel mosfet A1SHB/SI2301 in SOT23?Needs to be able to handle more power (maybe 2A) and maintain same packing and pin arrangement...I am very confused with most of what i find like SK2301AA or NTR1P02T1G or SI2301CDS-T1-GE3 and what is most confusing is a myriad of parts with 2301 in their code which hint of this being the same part but with as low as 1A and as high as 4,5A Id

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 22, 2018, 04:31:05 pm
content: As I gathered, the SI2301 is a part from MCC:http://www.mccsemi.com/The Si2301DS is a part from Vishay. Their characteristics are close enough. But it's marked as obsolete. TheSI2301CDSis still active at Vishay and has similar, albeit higher current handling than the SI2301 and should fit your design's needs.I'm not sure similar part numbering among different vendors are supposed to get you equivalent transistors. You should always check characteristics before settling on any "equivalent" part.
Mosfet Selection Help, Infineon vs Vishay for Similar Values - Page 1
Forum section: electronics / projects

author: botvink
author_rank: Newbie
timestamp: October 05, 2025, 08:58:12 am
content: Hello friends,For my motor driver design I am in difficulty for selecting the suitable mosfet for 100V range, I am paralelling and eliminated all to 2 model:IAUMN10S5N016GAUMA1 - Infineon Technologieshttps://www.infineon.com/assets/row/public/documents/10/49/infineon-iaumn10s5n016g-datasheet-en.pdfAndSQJQ112E-T1_GE3 - Vishayhttps://www.vishay.com/docs/79384/sqjq112e.pdfBoth are 100V and have similar current ratings, 296A vs. 310A. Vishay is a bit more affordable, but I don't know if it falls behind Infineon in quality or if there are any other significant differences. What do you think?

author: xvr
author_rank: Frequent Contributor
timestamp: October 05, 2025, 03:23:48 pm
content: QuoteInfineon is only 220A Id (not 310A). 310A is a chip limitation, but pins and package itself will limit it much faster.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 05, 2025, 04:42:33 pm
content: Quote from: xvr on October 05, 2025, 03:23:48 pmBoth current ratings are completely meaningless, so it doesn't really matter.Calculate maximum actually achievable current from losses (Rds_on and switching losses, latter of which are harder to accurately model) times thermal resistance. Which depends on how heatsinking is done. And maximum ambient temperature.

author: mzzj
author_rank: Super Contributor
timestamp: October 05, 2025, 06:37:23 pm
content: Look to be roughly similar parts. Infineon has bit lower gate charge and thus easier to drive. Body diode ballpark similar.Vishay has better avalanche ratings but this could be down to different testing methology.Vishay also has tons of better forward safe operating area but I suspect it could be unrealistic or they even mixed up milli- and microseconds.Difference between parts is 200-fold. For motor drive this is probably largely irrelevant except fault/transition conditions.
MOSFET switch in SweetiePie to turn on Raspberry Pi - Page 1
Forum section: electronics / projects

author: asgard
author_rank: Regular Contributor
timestamp: August 26, 2014, 08:44:40 pm
content: Setup:I have been working on a little adapter device to bridge between an RPi and a lapdock originally used with a (now obsolete) Atrix 4G Evo cell phone. There is a male micro HDMI connector and a male USB connector in a saddle configuration. The adapter, called the SweetiePie looks like this (schematic, too).That's some of the setup. Additionally, I have since learned that the Atrix will not turn on the 5V USB unless the HDMI cabling shorts the DDC/CEC/GROUND to the other grounds, which is the case inside the Pi's and the BeagleBone Black. So if any of these boards are connected to the HDMI output of the SweetiePie then the 5V is turned on in the USB. The way the Atrix seems to accomplish this is to direct about 10V across a 160K pullup resistor at DDC/CEC/ground, with a current limited to approx 64 uA. When that signal is shorted to ground it is supposed to indicate to the Atrix that the phone is cradled and therefore turn on the 5V and the video on the lapdock. I have connected a hacked cable directly from the Atrix to the Pi with success, but I wanted to reduce the spaghetti, so the SweetiePie fits precisely in the Atrix cradle. My problem is that for some reason, because of the P-channel MOSFET on the high side the output voltage is not at 5V solid, as I expected, but rises only to about 4.1V for 100ms, then does a slow (capacitor-like) fall back to ground for another 150ms, which then repeats the cycle. I am wondering if I have missed something. I have given some thought of putting a beefy electrolytic (or tantalum) capacitor from the high-side drain to ground, but that would only be a guess on my part right now. I always thought an N-channel would only look like a series resistor to the voltage going through it.J.R. Stoner

author: dannyf
author_rank: Super Contributor
timestamp: August 26, 2014, 08:54:53 pm
content: 1) you probably want to articulate your issues in a few sentences;2) you probably want to make your schematic simpler and easier to read;3) you probably want to figure out how n-ch or p-ch mosfets work.Hope it helps.

author: asgard
author_rank: Regular Contributor
timestamp: August 28, 2014, 06:24:44 am
content: Following up a bit...I put a 1uF capacitor across pins 4 and 8 of the FET, which adds some AC decoupling from the P-channel gate, so that cleaned up the gate level a bit, but the sort-of sawtooth effect on the 5V output remains.I have done some more measurements and have discovered that the 0.8V supply feeding into the HDMI is going into the rpi, and colliding with the 5.094V measured at the USB end. The obvious thing would be to put a diode in series with the USB output 5V supply to the rpi. The USB spec says the 0.7V diode drop puts the available power at the USB end at about 4.3V which would be too little to supply the pi, but can the 0.8V from the HDMI be useful to counteract the diode drop?
mosfet switch, snubber design? - Page 1
Forum section: electronics / projects

author: Boschi
author_rank: Regular Contributor
timestamp: April 15, 2018, 05:14:29 pm
content: im developing a project that is basically a PWM controller for a 100A resistive load.i started a while ago on this thing, so i have already designed the switch and the PCB of it.basically is a auirfs8409-7p driven by an ucc27524.the problem is the ESL, which cause a voltage spike on the mosfet (40+V, not more because then it goes in avalanche). i have attached some screenshot at 8V and 2A circa.i have calculated the parasitic inductance and the parasitic capacitance (2uH and 2.7nF), and i did some test with some snubber, improving the situation a lot.the snubber is a RC snubber with 2uf and .3 ohm of resistance.with the snubber i pushed a bit the current, and in the pictures is going at 4A. i dont get why by rising the duty cicle the spike voltage rise. im using some cheapo capacitor, so they probably are X5R, and are losing capacity as the RMS bias voltage rises, right?how can i choose the right R and C value?also, is a RC snubber the best choice? should i try with a RCD snubber instead, or maybe adding a zener in order to clamp excessive voltages?i tried to do some math, and looks like that a 100A a 2uH inductor stores 10mJ of energy. this means that at 1Khz it would dissipate 20mJ per cicle, so 20W?in the W SNUB 50DC (2) why it takes 6uS for the voltage to rise? its because the snubber capacitor is charging?PS: the snubbing capacitors (2 in parallel) are ceramic, so with probably .2 ohm of ESR i assumePPS: i have added another screenshot using just a single ceramic capacitor as a snubber, because why not? and its the best for now (@4A).
MOSFET switched H-Bridge ideas required - Page 1
Forum section: electronics / projects

author: devguy
author_rank: Newbie
timestamp: October 21, 2020, 02:40:03 am
content: I have the circuit attached that uses an H-Bridge to drive an emitter coil at 125 kHz. It reversed direction every 1/2 cycle to result in 0 DC average voltage across the emitter.The P Channel Supplies Power, while the N-Channel switches in the required load (changes current through emitter).The P Channel on one half the bridge switches on at same time as opposite side of bridge N channels.The emitter does not provide a DC path so the first problem is that Charge stored in output capacitance of the P channel does not fully discharge until next cycle is part way through (and therefore clashes with same-side N fest switching on, causing excessive heat and loss of power). The 1k discharge caps have been lowered to 330R and this helps but I cannot lower then further or the minimum power setting is too high for my application.Second issue is the R/C time constant for the N channel fet switching is causing the input to driver IC to be turned into triangle waveform (I can fix this by moving switching to input of driver and let driver directly control the N channels.So, I am looking for ideas for a typology that implements a full H Bridge to retain the 1/2 cycle change of polarity but also enables the current through the emitter to be adjusted digitally.Even a programmable current source might work but not sure how best to set that up for bi-directional polarity.If I use only the totem-pole output (P chan/N Chan like TC4490) and only drive current 1 way, it gets easy but I end up with an average DC across the emitter and loss of power (every second half cycle is 0 volts instead of -11.3V)Thanks for your ideas.
Mosfet to PWM a 20V load - Page 1
Forum section: electronics / projects

author: 0miker0
author_rank: Newbie
timestamp: February 02, 2023, 07:22:48 pm
content: Hello all,I'd like to pwm a 20V led light strip using an esp32 gpio pin. I have something started below and am wondering if I'm on the right track or have something drastically wrong? Any pointers or tips would be greatly appreciated.

author: jmw
author_rank: Frequent Contributor
timestamp: February 02, 2023, 07:47:00 pm
content: Have you tried it in spice? I think those 100k resistors might interact with the gate capacitance of Q3 to skew or wreck your PWM, depending on the period. There are IC PWM LED drivers that will do this for you, or you could also consider a complementary pair topology.

author: 0miker0
author_rank: Newbie
timestamp: February 02, 2023, 07:49:04 pm
content: 100K is definitely too much and I'm working on correct values now. Checking out other circuits and am wondering if R17 can be completly removed.

author: ledtester
author_rank: Super Contributor
timestamp: February 02, 2023, 07:52:07 pm
content: Why not just use a single N-MOSFET, eg:

author: Zero999
author_rank: Super Contributor
timestamp: February 02, 2023, 09:16:45 pm
content: Quote from: 0miker0 on February 02, 2023, 07:49:04 pmRemoving R17 will only speed up the turn-on time. R11 means the discharge time is slow, making it take a long time to turn off.Use a MOSFET driver.

author: bson
author_rank: Unknown
timestamp: February 02, 2023, 11:32:44 pm
content: Consider an isolating gate driver, like a TI UCC5304.

author: inse
author_rank: Super Contributor
timestamp: February 03, 2023, 03:41:21 am
content: Depending on your PWM frequency, you might get along with 1k for R10/17.You need to take care not to exceed the max Vgs, so either keep R17 or use a zener diode.

author: Zero999
author_rank: Super Contributor
timestamp: February 03, 2023, 11:03:53 am
content: A MOSFET driver circuit can be made with a few BJTs.What's the output voltage from the microcontroller?Here's an example.The output voltage between the gate and source, depends on voltage from the MCU and the values of R1 & R2.VO= (VI-VBE)(R2/R3)-VBEVBE= 0.7V Typical for the base-emitter voltage of a BJT.VO= (VI-0.7)(R2/R3)-0.7VI= V2 = 5VVO= (5-0.7)*(3.3k/2.2k)-0.7 = 4.3*1.5 - 0.7 = 6.45 - 0.7 = 5.75VYou might want a higher gate drive voltage than 5.75V and your MCU is probably run off 3.3V, so the values of R1 & R2 will need to be altered.

author: 0miker0
author_rank: Newbie
timestamp: February 03, 2023, 12:00:54 pm
content: Tnaks and I may give this a try. I'm a little tight on space and fitting in a moset driver may not be possible. Also the pwm speed is really slow.

author: shapirus
author_rank: Super Contributor
timestamp: February 03, 2023, 03:19:15 pm
content: Quote from: 0miker0 on February 03, 2023, 12:00:54 pmEven so, you want to make sure that your edge rise/fall times are short to minimize the time during which the transistor stays in between fully on and fully off states, where it dissipates extra power as heat.
MOSFET trigger using AC - Page 1
Forum section: electronics / projects

author: ivancho
author_rank: Newbie
timestamp: October 16, 2016, 01:17:46 am
content: I have a voltage divider across the mains using a single diode on neutral (rectification) charging a CAP. I want to use this configuration to drive a MOSFET eventually in line with the mains.The main issue I currently have is calculating the the voltage level expected at the cap. I see the cap charges with respect to the "hot". I am trying to calculate the values of the resistor along with the cap so that I get a Vout.The simulation puts me at Vout=35V with the values shown. Dismiss D2 as it will be the protection to the FET gate. Vin=162.63 (peak) ~(115Vrms)(http://imgur.com/a/pW8ZZ)The voltage divider of 100K resistors Vout=80V half rectification. But how do I get 35V from there based on the simulation results?Thank you,

author: Ian.M
author_rank: Super Contributor
timestamp: October 16, 2016, 03:11:16 am
content: You cant treat it as a simple voltage divider - when the diode isn't conducting, it isn't!

author: ivancho
author_rank: Newbie
timestamp: October 16, 2016, 05:22:09 am
content: Well I understand that but how do you calculate the actual value expected.What would you rate your cap at?The circuit seems simple enough to derive the actual voltage expected at the cap. But I quite can't make the connection.Suggestions?

author: Ian.M
author_rank: Super Contributor
timestamp: October 16, 2016, 05:37:19 am
content: Solving it mathematically is going to be a real PITA. Its a simultaneous equation involving a bounded integral of a sine wave - which is why most sane people would use a SPICE package.It can be solved graphically. Plot Vin, then for equal value resistors, the capacitor will settle at a voltage where the area between the straight cap voltage line and the portion of the Vin sinewave above it is equal to the area under the straight line. Counting squares and tedious iteration will be required. . . .A 63V cap should be safe no matter what idiocy its supplied from - upto and including 120V DC supplies!
Mosfet Vgs +- rating - Page 1
Forum section: electronics / projects

author: Craftplorer
author_rank: Contributor
timestamp: November 26, 2018, 04:28:26 pm
content: Hi,i was looking at following mosfet from Fairshieldhttps://www.mouser.de/datasheet/2/308/FDBL0065N40-1305438.pdfor from On Semihttps://www.mouser.de/datasheet/2/308/NTMFS5C404N-D-1067128.pdf. Both have a Vgs of +-20V so does it mean that I can only apply 10V to the gate?

author: ajb
author_rank: Super Contributor
timestamp: November 26, 2018, 05:00:55 pm
content: No, that means you can apply an absolute maximum of +20V or -20V to the gate, relative to the source. I'm not sure how you got 10V from that.However, it is not wise to use design your project based on absolute maximum ratings, as this leaves you no margin for error. Electrical noise, or component tolerances, or other factors can easily push your device over the edge and cause damage to components. Generally, MOSFET gates are driven to 10-12V in situations where you want hard switching and low on resistance. This leaves a fair margin between the operating conditions and the absolute maximum ratings of typical transistors.

author: Benta
author_rank: Super Contributor
timestamp: November 26, 2018, 05:02:24 pm
content: It means you can apply +20 V or -20 V to the the gate without destroying the device.Designing to the maximum rating is not a good idea, though, I'd go to +/-15 V tops.

author: Benta
author_rank: Super Contributor
timestamp: November 26, 2018, 05:03:11 pm
content: Whoops, simultaneous posting. At least we agree

author: Craftplorer
author_rank: Contributor
timestamp: November 26, 2018, 06:03:55 pm
content: Thank.I was confused because opamp often say +-36V for dual supply but after i thought about it, it makes sense to meAnd of cource i didn't want to drive the fet with 20V. The project ist powered by 11.4v

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 26, 2018, 06:17:03 pm
content: you cannot conclude from an opamp to a FET - these are two complete different devices.actually 36V is the absolute maximum rating for most jellybean opamps, the normal operational range is +/-15Vdon't orient you on the absolute maximum ratings, they should never be touched under normal operating conditions

author: perieanuo
author_rank: Frequent Contributor
timestamp: November 27, 2018, 10:16:50 am
content: Quote from: Craftplorer on November 26, 2018, 06:03:55 pmHi, your 11.4 volts don't count.you can have a spike from another pcb sitting next to yours or induction or.. or..That's why every power mosfet have some 12-15V zener protecting gate-source junction.don't miss this on power boards with mosfets as final stage.Regards,pierreEnvoyé de mon iPad en utilisant Tapatalk
MOSFET Voltage Regulator - Page 1
Forum section: electronics / projects

author: Jon86
author_rank: Frequent Contributor
timestamp: August 03, 2013, 10:00:34 am
content: So I built up this circuit for a Low Dropout Mosfet based voltage regulator, I tested it in multisim and it works perfectly with a dropout of less than 0.5v.After reading about N-Channel mosfets I'm beginning to think it won't work. Can anyone tell me what will happen when I hook this circuit up?Why would an N-Channel not work?

author: Dave
author_rank: Super Contributor
timestamp: August 03, 2013, 10:15:15 am
content: I think it will work, but it won't be anything near low dropout. An average N-channel MOSFET has the Vgs threshold at about 1.5-2V. Your opamp output (the gate of the FET) will go close to the positive power rail, so that means the source will be 1.5-2V lower than that. That means at least 1.5-2V dropout.Also, you will need some capacitors on the input, output and in the feedback loop, so your circuit won't oscillate.

author: Jon86
author_rank: Frequent Contributor
timestamp: August 03, 2013, 10:29:37 am
content: Thanks for the response, but I'm just not understanding why the the dropout will be so high? I mean, surely if the the Opamp takes the gate to the threshold voltage then the gate will turn on completely and have only a few mV of drop?

author: cyr
author_rank: Frequent Contributor
timestamp: August 03, 2013, 10:39:26 am
content: Yes but the opamp can't drive the gate any higher than the input supply voltage, unless you power it separately from a higher voltage supply of course.

author: Jon86
author_rank: Frequent Contributor
timestamp: August 03, 2013, 10:48:08 am
content: But the gate doesn't have to be higher than the source voltage, does it?

author: Andy Watson
author_rank: Super Contributor
timestamp: August 03, 2013, 10:49:47 am
content: Quote from: Jon86 on August 03, 2013, 10:48:08 amYes.

author: Jon86
author_rank: Frequent Contributor
timestamp: August 03, 2013, 10:55:53 am
content: Ah. So with a P-Channel can it be lower than the source?

author: Dave
author_rank: Super Contributor
timestamp: August 03, 2013, 11:13:01 am
content: Correct.In fact, the gate potential HAS to be lower than the source, if you want to turn a P-channel FET on.

author: Jon86
author_rank: Frequent Contributor
timestamp: August 03, 2013, 11:13:35 am
content: Okay thank you. I finally understand the difference now

author: Frant
author_rank: Regular Contributor
timestamp: August 04, 2013, 02:35:01 am
content: Quote from: Jon86 on August 03, 2013, 11:13:35 amYes, but it's not so easy. There are integrated voltage regulators with a P-channel MOSFET and some rare examples with an N-channel MOSFET and a charge pump circuit providing the needed gate voltage higher than that at the input. A positive voltage regulator based on a P-channel MOSFET (or a PNP transistor) can have stability issues. Voltage regulators have been an ubiquitous topic for decades. All the major manufacturers design and make them all the time, so we can assume that they have already tried just about everything.
Mosfet won't turn off completely (Gate tied to GND)  - Page 1
Forum section: electronics / projects

author: 24602
author_rank: Contributor
timestamp: January 29, 2021, 03:27:51 am
content: Hey AllGot some VNB14NV04 N channel mostfets connected up to some 12v (testing also with 24V) LED strips, super simple stuff.But noticed when setting the LEDs to 0% they're still glowing. Thought it was my driver but I connected the Gate directly to LED Supply GND and the same occurs.Confused as the I'm using the same mosfets as another product that works just fine with identical driver etc.Ive pinched a photo/schematic showing what I have setup initially just change R1 to 10K and R2 to 47R and add a mosfet driver. But at the moment removed everything from the gate and connected it directly to GND.Swapped out the mosfet incase I somehow blew the first one up.Anything I have completely missed?

author: uer166
author_rank: Super Contributor
timestamp: January 29, 2021, 03:41:34 am
content: What is the current through the glowing strip? Datasheet specifies 25uA leakage at 70C which may be enough to make some high efficiency LEDs visible.

author: 24602
author_rank: Contributor
timestamp: January 29, 2021, 03:58:24 am
content: Yeah that could be it - getting 11.2uA @ 24VWhere did you find the leakage current? - just scanned through the data sheet and couldn't find it againJust odd as an existing board with the same mosfet connected up the same way has no sign of leakage. I'll have to hook it back up and measure if there's any leakage.

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2021, 05:10:04 am
content: This datasheethttps://www.infineon.com/dgdl/irlml2502pbf.pdf?fileId=5546d462533600a401535668048e2606Search for "Drain-to-Source Leakage Current".And yes, modern LEDs are stupid efficient.

author: 24602
author_rank: Contributor
timestamp: January 29, 2021, 05:30:41 am
content: ataradov - But that data sheet isn't for my part?

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2021, 05:33:53 am
content: But that's the part on the picture.In your datasheet this parameter is called "Zero input voltage drain current" (I_DSS). And it is 30 uA for your conditions.

author: BrianHG
author_rank: Super Contributor
timestamp: January 29, 2021, 05:34:45 am
content: Quote from: 24602 on January 29, 2021, 05:30:41 amEven worse leakage current.

author: 24602
author_rank: Contributor
timestamp: January 29, 2021, 05:36:49 am
content: Quote from: ataradov on January 29, 2021, 05:33:53 amYeah I can see why that was confusing, I have removed the image, My part is VNB14NV04

author: viperidae
author_rank: Frequent Contributor
timestamp: January 29, 2021, 05:38:14 am
content: Maybe putting a 100k resistor in parallel with the LEDs would drop the voltage across them enough so they don't turn on.

author: 24602
author_rank: Contributor
timestamp: January 29, 2021, 05:44:41 am
content: Quote from: viperidae on January 29, 2021, 05:38:14 amWorked straight wayThanks!
MOSFET/IGBT driver HCPL avago 316J - Page 1
Forum section: electronics / projects

author: Fateh Singh
author_rank: Newbie
timestamp: June 03, 2017, 10:44:59 am
content: We are trying to design an EV motor Inverter . The aim is >20KW power with a Li battery about 200V giving 100 amp.I have some high quality ROHM SiC Mosfets and for drivers I designed in this Avago 316J- optically isolated input, Desat capable, fault reportingoptically back to controller etc.I designed the four DC-DC converter supplies for ( +20Vand -5V isolated ) for three high side switches and One Common for LOw side switchesusing SG3525 for push/pull action and feedback PWM control using the common 817 and TL431 chips. This works.Then I started on checking Avago 316J - every thing looks ok- input 5v pulse signal from a VCO (4046); Output supplies as per schematic OK.BUT NO OUTPUT. Change chip - same status. Can somebody help , please?

author: Le_Bassiste
author_rank: Frequent Contributor
timestamp: June 03, 2017, 01:47:34 pm
content: be sure that the 316j can handle the Common Mode Slew rate that it is going to experience with SiC. datasheet says 15kV/usec, but with SiC, you want to have CMTI better than 50..100 kV/usec. if your circuit is not going beyond 15kV/usec, then you could use NOSFETs and save some money.as for the rest: check !RESET = HI, check !FAULT= HI, all DC voltages properly referenced to the respective grounds (or SOURCE of SiC), all voltages = OK and well above UVLO, DESAT input either properly adopted to SiC (won't work out-of-the-box for SiC, but only for IGBTs, and then it sucks), or -better for diagnostics here- disabled.hth
MOSFETs for polarity-independent input - what are the limitations? - Page 1
Forum section: electronics / projects

author: grandaspanna
author_rank: Contributor
timestamp: November 03, 2022, 04:57:30 am
content: I wanted to add reverse polarity protection to a simple project, but got thinking why not make it accept input regardless of connection.It's a relatively low power/low voltage scenario - 12-14V DC input and peak current around 2-3A.I thought about a classic diode rectifier setup, but then stumbled across MOSFET setups which have a lower forward voltage drop and thus less power wasted.Threw together the attached prototype with 2 N-channel and 2 P-channel MOSFETs and it seems to work. MOSFETs used here are rated for approx 10A.Question: other than cost associated with the extra parts, what are the shortcomings/risks of doing this?The schematic is a screen grab of Diptrace and the photo is the prototype board with USB-A connector for scale.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: November 03, 2022, 09:57:51 am
content: Isn't this how rectifiers have been made on chip for a while now? I think active rectifiers are also common in VFDs and other high-power scenarios.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 03, 2022, 10:08:36 am
content: The active rectifier may have some short time current spikes, if the current/voltage is changing polarity very fast, e.g. with major transients in the supply, maybe bouncing contacts when disconneting. It should be OK for the connect case (just a bit delay to turn on). This may mean a slightly larger chance for failure from transients. A simple passive rectifier is usually more reliable, though also limited speed. The specs for automotive use want quite some protection against transients.
Mosfets manufactured by CYG WAYON, what to think about them ? - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: August 27, 2019, 12:21:35 pm
content: Hi folks,I just listing trough actual semiconductors prices and I see new manufacturerThey start here in center of Europe distributing semiconductors from company namedCYG WAYONIt look like new Chinese factoryThey dont have big variety of product, but what they have is at interesting pricesI expect there will be plenty of medium sized manufacturer in Asia who have no distribution to other parts of worldJust wonder if you have some experience with this manufacturer or similar ones
Most cost effective / efficient way to charge lifepo4 off generator.  - Page 1
Forum section: electronics / projects

author: qwaarjet
author_rank: Regular Contributor
timestamp: August 31, 2021, 02:36:06 am
content: I'm in the process of building a an off grid house. I'm planning on putting in about 50-100kwh of lifepo4 (48v nom) batteries and for at least a few months a year I will need to charge them from a generator, 20kw industral skid, not some light duty backup house generator. I have a lot of experience charging batteries using large programmable powered supplies, Tdk genesys and the like. However that adds a lot of cost and burns power. So I have this crazy idea that I could hack/ build a new voltage regulator for the generator power head and then just use bridge rectifier off the generator windings to charge the battery bank directly. Current sense on the generator output would be used to control the excition coil on the generator. To avoid the crap power factor from the rectifier the excition voltage would have to change on per cycle basis. I done a bit research but pretty much everything I've found is about making more efficient converts off of mains power not modifying a mechanical generators output.Any suggestions?

author: TheMG
author_rank: Frequent Contributor
timestamp: August 31, 2021, 04:29:58 am
content: There are several off grid inverters on the market that have the capability to also charge batteries, at the same time as powering the loads. They call this generator assist mode. Some can even be programmed to automatically start and stop the generator based on state of charge.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 31, 2021, 04:54:39 am
content: Just get a few "telecom rectifiers", they're pretty cheap on the surplus market as in $20 for 2kW. Or for such a large battery, look at running a higher voltage and using a EV charger module. If you haven't already bought the generator, one path worth considering is to get the engine and CVT from a Prius and hacking it to be used as a generator.

author: qwaarjet
author_rank: Regular Contributor
timestamp: August 31, 2021, 09:20:51 pm
content: I want to keep charge and inverter as separate hardware as it give much more flexibility in system design and flexibility. Fyi I'm using cotek sr1600 inverters. I have not found rectifiers in the $20 range that I would trust at all even used. got some links? . The best $/Amp hardware I've found that has control and basic diagnostics is the tf3000 series supplies from slpower.

author: james_s
author_rank: Super Contributor
timestamp: August 31, 2021, 09:44:05 pm
content: When I charge LiPos in the field without power available I use my Honda EU2000i generator feeding a 12V server PSU powering my chargers. It's a lot of conversion steps but it's the equipment I have and it works fine to do that. If I were building something dedicated to charging batteries I think I would look at getting a 24VDC generator and using that directly to power the LiPo chargers.
Most efficient way to wire door/window NC magnets (addressable)? - Page 1
Forum section: electronics / projects

author: onesixright
author_rank: Frequent Contributor
timestamp: October 15, 2019, 07:15:26 am
content: Hi All,Im installing a bunch of new doors and windows. I would like to fit them with magnet contacts to detect open/close state, preferable going into a raspberry pi.I did some reading and apparently you have to versions the NC (normal closed) and NO (normal opened) ones.I understand that for alarm systems you would use the NC version. Makes sense.My question, if I would like toidentifywhich window/door is/are open, what would be the best/easiest way to addresseachsensor?Obviously some bus style would be cable wise (length) most efficient, but that means I need some way too address each sensor (RS485?). When pulling wires in a star style would be much easier, but more wires.Situation: 3 floors, house is completely being renovated, so cable access is no problem.basement: 4 doors / windows1st: 8 doors / windows2nd:8 doors / windowsLooking forward to some feedback / best practiceThanks!

author: jonovid
author_rank: Super Contributor
timestamp: October 15, 2019, 07:34:49 am
content: change of state detection maybe the best chose with security setups.triggered when the input changes state.allowing for brief time of switch bounce.as always allow for RF blocking and other long wire isolation to keep your raspberry alive

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: October 15, 2019, 02:50:22 pm
content: Best practice is to divide the stations into zones and not concern yourself with exactly which station in a zone is in the wrong state. Just saying...Check out the DS2413 dual addressable GPIO for an easy, almost turn-key, two-wire solution for what you want to do. Breakout boards available from Adafruit and others.

author: soldar
author_rank: Super Contributor
timestamp: October 15, 2019, 04:15:15 pm
content: You can have a loop with n switches and each switch has a resistor in parallel. make the resistors powers of 2 and you can know directly what switches are open or closed.For instance, you have five switches in series with resistors in parallel with each switch. The values of the resistors are 1K, 2K, 4K, 8K, 16K.If the loop measures 10K then you know switches 2 and 4 are open.If you do a loop alarm do it with double parallel cable, better if twisted, to minimize electromagnetic interference. Don't make a loop around a room. Have the return come back the same way it went out.