hybridfree/eevblog-posts huggingface dataset:
mosfet driving a led using an attiny85 and linear regulator - Page 1
Forum section: electronics / beginners

author: plcking
author_rank: Newbie
timestamp: March 03, 2022, 01:29:41 am
content: I have a linear regulator ( lm7805) supplying power to pin 8 of the attiny85-20PU. This is because I have a 12v power supply that has to be dropped down to attiny friendly 5v. Pin 5 (PB0) of the attiny85 supplies power with a 800 ohm resister to the gate of the mosfet PSNM017. The drain is connected to a led and 100 ohm resistor.I have programmed the attiny to flash the led at various frequencies in a loop. The problem is that the led begins to flash erratically after the first iteration of the program loop.The led will flash normally when I remove the linear regulator and supply 5v power directly to the attiny.What is the problem ? Need capacitance ?Pat

author: phatroug
author_rank: Newbie
timestamp: March 03, 2022, 01:41:40 am
content: Good practice to follow the datasheet. Do you have a scope you can look at the output power?The datasheet says: lm7805 specs were measured with .33uF input cap and .1uF output cap.input cap - might be needed cause regulators tend to dislike inductive suppliesoutput cap use .1uF or 1uFreport back!note your linear supply is dissipating lots of power: 7V drop * Current of the load from the uC. If the rest of your system is sinking big power it might be wise to investigate a switching regulator which at high current will be more eff.

author: plcking
author_rank: Newbie
timestamp: March 03, 2022, 04:00:00 am
content: well, it certainly pays to "RFTM" !I placed a 100 nf capacitor across the output, and the same across the input ( I didn't want to chain 3 X100 nf capacitors across the input to make 300 nf because my these small capacitors are a pain in the ass ). The circuit works perfectly now !Why the spurious signals when not using the capacitors ?Thanks for your expert help !By the way, I am driving a motor with the mosfet by using a 7Ah battery, so power wastage is not really an issue ( ie. the 7V X output current of the lm7805 )Pat

author: Circlotron
author_rank: Super Contributor
timestamp: March 03, 2022, 05:27:14 am
content: A linear regulator is a particular form of amplifier, and as such it can oscillate if the wires to it are too long.
Mosfet driving circuit - Page 1
Forum section: electronics / beginners

author: andrejsstrumfs
author_rank: Newbie
timestamp: January 22, 2018, 09:36:22 pm
content: Hello all!I'm a newbie with electronics and i need a bit of reality check for my circuit. That's basically a n-mosfet low side switch driver. There's one thing - the low side power can go from 0 to -35 volts. I probably need to adjust the resistor values, but first i want to be sure that i got this on the right track. The switching is done manually, so no worries about large gate discharge resistor.Thanks

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 22, 2018, 10:31:04 pm
content: Is R3 necessary?

author: llkiwi2006
author_rank: Regular Contributor
timestamp: January 22, 2018, 10:57:00 pm
content: At a worst case low side voltage of -35V, you will be pulling 30mA thorough your zener, and dissipating 0.9W in R4. Make sure to use a resistor capable of handling 1W for R4.

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 23, 2018, 07:05:14 pm
content: Quote from: andrejsstrumfs on January 22, 2018, 09:36:22 pmWell actually depending on the load current and nature the mosfet switching speed could be important and certainly in the present circuit the turn-off will be slow possibly leading to mosfet destruction.Is there any reason the switch is in a 5V circuit ? why could it not switch the mosfet gate directly ? but perhaps you are intending to drive it from an mpu.Your circuit shows both 24V & 0-35V, perhaps that is a nominal and a range ?Finally is your load inductive ? if it is you will need a catch diode to protect the mosfet from avalanche.

author: andrejsstrumfs
author_rank: Newbie
timestamp: January 23, 2018, 07:38:48 pm
content: Quote from: Wimberleytech on January 22, 2018, 10:31:04 pmYou're right, not needed.Quote from: llkiwi2006 on January 22, 2018, 10:57:00 pmThanks. Larger R4 value would be better.Quote from: fourtytwo42 on January 23, 2018, 07:05:14 pmWell, maximum current will be 3amps, i think should be ok.Quote from: fourtytwo42 on January 23, 2018, 07:05:14 pmYes, i will drive the npn via 555 timer. Also that will allow turning on the mosfet when low side is all the way up to the ground?The +24 is simply because Eagle cad had that label on componentBit misleading, sorry.Yeah, catch diode is intended, just not shown here.Thanks!
Mosfet driving motor, is a protection diode needed - Page 1
Forum section: electronics / beginners

author: mribble
author_rank: Regular Contributor
timestamp: May 26, 2018, 10:59:56 am
content: I remember reading that sometimes when driving a motor with a mosfet the diode you typically place across the motor to prevent voltage spikes isn't needed. Can someone point me to an article or explain to me how to figure out if a diode is needed?In my example I'm using a motor with a stall current of 500 mA and will be using this mosfet:https://www.mouser.com/datasheet/2/196/irlml6244pbf-1228275.pdfThanks!

author: Zero999
author_rank: Super Contributor
timestamp: May 26, 2018, 01:16:25 pm
content: The only time a protection diode is not needed, is when the motor is brushless and has its own built-in driver circuit, such as a computer fan.In this case, we don't know what sort of motor you have. Assuming it's a brushed DC motor, then a reverse protection diode is required.

author: mribble
author_rank: Regular Contributor
timestamp: May 26, 2018, 01:52:16 pm
content: I did some looking and it seems the avalanche current can sometimes be used instead of a flyback diode, but people generally recommend against doing it this way. Also there are some extra tricks that happen for h bridge controllers, but that doesn't affect me.I have been convinced I'll add the diode. Thanks!
MOSFET driving  - Page 1
Forum section: electronics / beginners

author: yashrk
author_rank: Frequent Contributor
timestamp: July 13, 2015, 01:21:27 pm
content: Hey guys,I was just seeing multiple videos on MOSFET switching and many of them where emphasising on keeping stable ground connection and keep the switching part (N- channel with driver or P- channel) on the high side. Non of them where clear about why they prefer the high side switching over the low side switching.In what type of situations or circuits should I be concern about low side switching ??

author: Simon
author_rank: Unknown
timestamp: July 13, 2015, 01:50:21 pm
content: Low side switching is easier as everything is referenced to ground but it means that you disconnect your loads ground which is not always possible. High side switching gets around this but the gate voltage is then referenced to the positive supply so it's hard when say you have a 12V circuit with a 3.3V control to control a gate that is at 12V when off and 9V when on. Level transitioning is required.

author: yashrk
author_rank: Frequent Contributor
timestamp: July 13, 2015, 02:00:02 pm
content: Ohk so if its possible to switch the load using ground (which in my case is possible as its just a battery charger circuit) then I should go for it and it doesn’t have any other problem right ?And if there is need of N- channel in high side what kind of ICs or bootstrap circuit do you prefer (battery is of 12V hence the gate voltage won't go too high)

author: Simon
author_rank: Unknown
timestamp: July 13, 2015, 02:05:33 pm
content: You can use N or P channel for highside, P is easier but N channel mosfets are cheaper for big ones and have better specs so if it is a lot of power it makes sense to have the bootstrap circuit and the N channel on a highside.

author: yashrk
author_rank: Frequent Contributor
timestamp: July 13, 2015, 02:14:01 pm
content: Thank you for the reply but just want to know what types of bootstrap circuit do you prefer or which ICs (easily available) are used ?

author: PSR B1257
author_rank: Frequent Contributor
timestamp: July 13, 2015, 03:07:46 pm
content: Depends of how you want to switch the MOSFET.For PWM (duty cycle from 0.1 to 0.9 or there about and not too low frequencies) operation ausualbootstrap circuit will work.For static switching (i.e. DC=1 or low switching frequencies) you need an auxilary pule generator, which is charging the boot strap capacitor.You can build up such a circuit with a NE555 or use an IC likehttp://www.intersil.com/content/dam/Intersil/documents/isl6/isl6801.pdf
Mosfet Equivalent - Page 1
Forum section: electronics / beginners

author: salcolme
author_rank: Newbie
timestamp: April 28, 2025, 01:40:40 pm
content: Good Afternoon, I need some help with a back light driver board on a 32" panasonic television. Two mosfets are shorted notation is K3569 although on the web this seens to be prefixed by 2s i believe. These are described as obsolete so are only available from Chinese sources that seem a bit dodgey to me. I have looked for an equivalent without any luck. Any advice on eqivalent options would be helpful. Kind regards Tony

author: benj38
author_rank: Frequent Contributor
timestamp: April 28, 2025, 05:05:38 pm
content: I would say TK650A60F would be one possible modern cheap replacement (currently $1.75 at Mouser) with almost identical characteristics.If it were my television, I would not hesitate to use it as a replacement.

author: salcolme
author_rank: Newbie
timestamp: April 30, 2025, 04:37:15 pm
content: Thanks Benj Really appreciated Tony
Mosfet equivalent - Page 1
Forum section: electronics / beginners

author: A r a s h
author_rank: Newbie
timestamp: August 14, 2021, 12:48:28 pm
content: Hi allI am dealing with repairing a PSU equipped with 4 Mosfets. Three of which are 600v6A vgs30v. including 2* P0660A and 1* K4098. The K4098 is on separate heat-sink near primary bulky 450v capacitor and the two P0660a are on another heat-sink. The problem is no equivalent Mosfet referred on Alltransistor is available in my country. My only choices are STP9NK60z and UTC6N60 or maybe waiting for importing from china two month later!My dilemma is:if I stick with STP9NK60z and replacing two P0660, although the Rds would be fine but the output capacitance would be higher and subsequently(as my knowledge confirms ?) the Qg would be higher around 38 compared to 20 value !On the other hand if I go with 6N60 the Rds compared to P0660s would rise to 1.5 and Tr would also be twice the value equals to 70ns.If you were in my shoes which one you would choose to replace those two P0660s and one K4098?Thanks

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 14, 2021, 09:09:02 pm
content: 6N60 has typical Rds = 1.0 R, and 1.5 R max, so it seems very similar to K4098.Quite often we may use a bit more powerful MOSFETs like STP9NK60z too, it depends on the exact circuit. But the probability it'll work OK is quite high.

author: A r a s h
author_rank: Newbie
timestamp: August 15, 2021, 06:11:14 am
content: Thanks Vovkdo you have any idea why theTrparameter on6N60compared to4098is double? I thought the greater Rds would cause so, also if you had no choice which one would you choose to replace thoseP0660s?

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 15, 2021, 04:21:22 pm
content: Tr (and other T) depend highly on an exact test circuit. So in equal test conditions, they may vary much less. Or it may not make an issue in a real design.In an ideal situation, I would try both with oscillograph.I think I'll start with 6N60 and investigate them first. If ok - then ok. If not - then I would try a more heavy 9NK60. It is hard to say something because I don't know anything about your circuit. I only know I'll order both types, definitely.
MOSFET for BLDC Motor - Page 1
Forum section: electronics / beginners

author: LeoTech
author_rank: Regular Contributor
timestamp: November 15, 2019, 10:53:34 pm
content: Hello,I have spent quite some time on this, but I seem to have reached an impasse far earlier than expected.I am currently working on a project with some friends where we need to control a brushless dc motor. To save money we used one from an old drone and managed to find approximate specifications for it. Now I am tasked, with designing a custom controller board for it, but this is where I am stuck.The motor will be expected to run on somewhere between 10-20 V - depending on the batteries - and a couple of Amps. It will only be used in short bursts, and the torque required is very low.I have decided on a sensorless, i.e. no feedback loop, approach, but I have no idea for how to choose MOSFETs and gate drivers.Any recommendations for these? I am not looking for anything fancy nor very specialized, but rather a 'quick', one size fits it all solution.Any help is appreciated,LeoBtw, I have not really used MOSFETs before, except in dc load circuits, but will try fathom the relevant chapters inThe art of electronics.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: November 16, 2019, 12:33:04 am
content: Check this out.https://www.allaboutcircuits.com/technical-articles/sensorless-brushless-dc-bldc-motor-control/

author: langwadt
author_rank: Super Contributor
timestamp: November 16, 2019, 02:17:42 am
content: if you want quick and easy, just get an ESC from you nearest hobby store

author: LeoTech
author_rank: Regular Contributor
timestamp: November 16, 2019, 02:32:41 pm
content: Quote from: langwadt on November 16, 2019, 02:17:42 amWell, we kinda want to design as much as possible ourselves.Looking at your bio, you appear to be from Denmark as well, do you know of any store that would sell ESCs around here, except for the internet of course.Thanks,Leo

author: george.b
author_rank: Frequent Contributor
timestamp: November 16, 2019, 05:09:04 pm
content: Maybe one of those SOP-8 dual N-MOSFET thingies, like the IRF7103 or Si9945?

author: LeoTech
author_rank: Regular Contributor
timestamp: November 17, 2019, 07:17:30 pm
content: Quote from: george.b on November 16, 2019, 05:09:04 pmThat's exactly what I am looking for!Thanks!Do you by any chase have any experience in using these in BLDC motor controllers?Leo

author: george.b
author_rank: Frequent Contributor
timestamp: November 18, 2019, 12:35:24 am
content: Quote from: LeoTech on November 17, 2019, 07:17:30 pmNot really, not yet. I've been looking into designing a BLDC motor controller myself, though, and those are the MOSFETs I'll try to source

author: Benta
author_rank: Super Contributor
timestamp: November 18, 2019, 07:32:42 pm
content: Quote from: LeoTech on November 15, 2019, 10:53:34 pmSensorless BLDC drive isnotwithout feedback, but uses back EMF for feedback, thus requiring a certain rotation speed before it works.Are you perhaps talking about PMSM drive? This is a different control topology, but the same type of motor.
MOSFET gate current / waveform. Does it vary with  load on the device? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 28, 2015, 01:28:44 pm
content: Does a MOSFET's Gate current vary with the load on the device across Drain and Source? If you `scope a Gate switching waveform, say in a SMPS, does the load affect the waveform? Thanks. Just curious as the driver IC for the Gates is advertised as being able to deliver up to 1.6 Amps, and I don't see why such high currents would occur. As an example here's my waveforms on two paralleled pairs of IRFP450 devices. There was no voltage / load on the output at the time. 136 kHz drive frequency. Will this vary when they are loaded?

author: retrolefty
author_rank: Super Contributor
timestamp: January 28, 2015, 01:32:50 pm
content: MOSFET gate current flow is only during the charging and discharging of the gate capacitance during transition between on and off or off and on, at DC conditions there is no gate current drawn even at full rated drain current.

author: c4757p
author_rank: Super Contributor
timestamp: January 28, 2015, 01:42:29 pm
content: During switching, yes, absolutely the load affects the gate current. MOSFETs suffer from theMiller effectlike nothing you've ever seen before...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 28, 2015, 01:48:31 pm
content: FWIW, 1.6A is pretty weak as a driver, but that's okay as 136kHz isn't terribly fast, and IRFP450 is a pretty terrible device, very old.Tim

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 28, 2015, 02:21:02 pm
content: OK, thanks, I'll read up on the Miller Effect later. As a matter of interest is there a more modern device that would replace the IRFP450's without a total circuit re-design? Cheers!
MOSFET gate protection - Page 1
Forum section: electronics / beginners

author: aheid
author_rank: Regular Contributor
timestamp: October 05, 2018, 01:34:12 pm
content: So I was just fooling around in LT Spice with a silly idea, and I got a bit surprised about the behavior of the gate voltage.The circuit is of a very simple electronic load. When looking a the transient response, I was confused about current goingintothe gate voltage source. So I put the diode D1 there, and sure enough, the voltage rose above that of the gate voltage source.It took me a little while before I recalled that a MOSFET has parasitic capacitors all over, and I assume this behavior is the result of the gate-drain parasitic capacitor.As such I assume that this behavior would occur if I were to build the circuit as shown, which means that there's a possibility for the gate-source voltage to go beyond the maximum rated value.If so, is it advisable to connect a Zener diode between the gate and ground to ensure the gate-source voltage stays within the rated values? Or is there a better way to protect the gate? Or is it a non-issue in real life?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 05, 2018, 03:06:21 pm
content: Yup, Cdg is a real thing, particularly on old transistors under most conditions, and newer transistors at low Vds.What are you protecting against? Are you expecting a very rapidly changing load voltage?Which, actually, you should -- mechanical contacts are amazingly fast, in the sub-nanosecond range, so the dV/dt from hot-plugging a source to a load can be quite exciting indeed!You'll want some inductance between the terminals and the transistor, and some extra capacitance at the transistor to help filter it. Probably an R+C as well, to dampen everything and help ensure it doesn't oscillate. Basic filtering stuff -- only use what bandwidth you need.That will probably leave enough change at the transistor that you'll still want some protection, and yes, a zener from ground to gate will do a fine job.Tim

author: aheid
author_rank: Regular Contributor
timestamp: October 05, 2018, 10:29:46 pm
content: Thank you for the confirmation and details!Well currently I'm just exploring and learning. I'm going to make my own electronic load, but not based on the shown circuit. It'll be a more "standard" one using an opamp for gate control.While I'm not expecting large dv/dt, that is also a function of me not being very experienced and don't know all that much about how real circuits behave yet.So if I understood you correctly, you mean I should put a small inductor (ferrite bead thing?) in front of the drain?
MOSFET gate resistor - Page 1
Forum section: electronics / beginners

author: jshonw
author_rank: Contributor
timestamp: December 04, 2011, 10:41:02 pm
content: I want to control a resistive type dc heater with a N-channel mosfet from a microcontroller using PWM, but I am not sure if a resistor at the gate is necessary? The rate at which I am driving the mosfet will be slow at maybe about 20hz from 0-100 duty cycle. If one is necessary, how do you select a value?

author: Psi
author_rank: Super Contributor
timestamp: December 04, 2011, 10:56:14 pm
content: Yeah, you should always have one.In this case it's more to protect the mcu though.So if your mcu port is 30mA max, 5v / 0.03A = 166R, so say 180R or no less than that.Note, this wont protect the mcu from a failed fet that has shorted drain to base if you have a drain voltage above 5V.It's more to stop the fet trying to pull more than 30mA in normal switching operations.If your driving a fets base pin from a mcu you want to select a fet with logic level gate drive.That way you can be sure your mcu will be able to turn the fet fully on.

author: jshonw
author_rank: Contributor
timestamp: December 05, 2011, 12:54:51 am
content: Thanks, I am going try that. I am using a logic level fet, so it should fully turn on from the micro.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: December 06, 2011, 01:17:39 pm
content: However, this might give you a dissipation problem, if the currents are high;Assuming a 1nF gate capacitance, this 180E resistor results in a linear operation of the mosfet for about 0.7uSec on each edge. This does not sound like much, but often this linear switching is the main contributor of total mosfet power dissipation.With the mosfet directly to the CPU, this high valued resistor does not really matter because the current sourcing capability of the uC is limited anyway.All that the resistor adds is a current limit to a more precise value (which is usefull from EMC perspective), and said cpu pin protection of course.When currents increase, this dissipation can be a huge problem, so that's where mosfet drivers come in. These devices are just simple push/pull drivers, but with serious current capabilities, often like 1amp or more. With such drivers, you're usually dealing with gate resistors much lower in value, often between a few and 10 ohms.So if the mosfet gets hot, you should consider a part with much lower gate capacitance or an external mosfet driver. Lower capacitance usually goes hand in hand with higher on-resistance, so that's not very helpfull usually, although there's an optimum between switching losses and conduction losses. Also the better the capacitance vs resistance ratio, the more expensive the mosfet gets.

author: Psi
author_rank: Super Contributor
timestamp: December 07, 2011, 01:41:41 am
content: yeahYou can also get logic opto isolators with push/pull high current outputs (1A)They can be useful to both isolate your fet from the micro and provide high current drive for the fet, all one package.
Mosfet gate voltage - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: August 10, 2022, 07:33:09 am
content: I need to repair laptop that may have faulty mosfet. The mosfet is marked like_3 D(3 with a line over it and then D )or another also with E like_3 E(the second line is like 3ITA or maybe 31TA)Anyone knows what transistor is it?5V is coming to gate on mainboard ( maybe because of a fault on the mainboard but maybe because it is P-channel.In case it were P-Channel mosfet, if I use 19V to gate, will the mosfet survive?

author: inse
author_rank: Super Contributor
timestamp: August 10, 2022, 10:15:02 am
content: What is the package and what is the MOSFET supposed to do?Did you measure it to be defective?

author: Jane
author_rank: Frequent Contributor
timestamp: August 10, 2022, 12:37:10 pm
content: They are the first and second power mosfet in 19V power rail

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: August 10, 2022, 01:38:09 pm
content: Are you sure they are not voltage regulators?

author: JustMeHere
author_rank: Frequent Contributor
timestamp: August 10, 2022, 07:09:28 pm
content: Find the chip driving the mosfets. Check out it's datasheet. Look at the datasheet for the TI BQ25720 for an example.

author: Jane
author_rank: Frequent Contributor
timestamp: August 10, 2022, 08:00:27 pm
content: Quote@JustMeHere: The chip is BD8616 I tried to find the datasheet but unfortunatelly I could not find it
Mosfet gets heated up at 5A or above. - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 19, 2016, 02:11:40 pm
content: 1. I have designed a circuit using TI's bq24650. Schemtaic & gerbers are attached. (Part of both are removed, only I have shown is high current path & mosfet).2. I have to operate circuit at 10A. Problem is Mosfet gets too hot at 5A or above even after 2 min of operation. Also Diode D1 PDS1040 gets heated up, but they are not very hot.3. Actual circuit has only one mosfet but it was rated for lesser current. So I have used 2 in parallel in my circuit. What could be issue with the circuit, are track length too short. I have removed solder msak layer from high current path as in gerbers you can check. Also while soldering I have placed a thick solder on these exposed tracks. Mosfet has high current rating as you can check in mosfet datasheet.

author: mmagin
author_rank: Frequent Contributor
timestamp: February 19, 2016, 11:18:39 pm
content: Is the inductor saturating?Does the BQ24650 have enough gate drive that the mosfets are switching hard and not spending time in the linear region?

author: nour
author_rank: Frequent Contributor
timestamp: February 20, 2016, 12:26:58 am
content: I am not expert but if the gate didn't get enough voltage to switch fully on I think it would be a problem, because the Rds on state wouldn't reach its minimum which will cause the transistor to get hotter at higher current

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 20, 2016, 02:30:51 pm
content: No, inductor is not saturating. It is rated for 32A sat.Max input voltage is 21V.Are these mosfet capabple of handle this current or some thing wrong in designing layout around these mosfets

author: mmagin
author_rank: Frequent Contributor
timestamp: February 20, 2016, 03:02:47 pm
content: Hmm. Assuming the mosfets are being driven cleanly, looking at the gerbers, you probably want better heat conductivity from the drain pads of those mosfets. As it is, you have the thermal relief (which makes it easier to hand solder). You probably want to eliminate that and have some thermal vias to copper on the other side. This kind of package is heavily reliant on those drain connections for thermal conductivity.A look at the waveform between the S1/D2 node and ground on a scope might clarify whether the mosfets are switching as expected -- don't forget that the connections need to be really short, including the ground lead.
Mosfet getting really hot - Page 1
Forum section: electronics / beginners

author: littlebill
author_rank: Regular Contributor
timestamp: December 16, 2024, 10:55:25 pm
content: So i am very confused and now stuck at a crossroad.I am building a powerbank system that uses a 2s2p liion with dual bms's to run a set of boost converters to get to 12.4vI purchased. IRLB4132 due to the low RDS on value, or so I thought.When pushing 10A through this IRL (max amperage for design) with a gate to source 1M resistor, and a 10ohm, gate resistor (to deal with ringing?)This thing is getting over 250F in ambient according to my thermal camera.I don't understand what I did wrong. I looked at various mosfets for BMS, that are tiny compared to this thing, and are barely getting over ambient (my 8A bms's barely get warm)what am i doing wrong.https://www.aliexpress.us/item/3256807388204026.html?spm=a2g0o.order_list.order_list_main.65.13701802M6blkN&gatewayAdapt=glo2usa

author: edavid
author_rank: Super Contributor
timestamp: December 16, 2024, 11:15:15 pm
content: Quote from: littlebill on December 16, 2024, 10:55:25 pmIf you bought them on AliExpress, there could be anything inside the package. Most likely it is a much smaller and cheaper part that has been remarked.However, what is the VGS?

author: littlebill
author_rank: Regular Contributor
timestamp: December 16, 2024, 11:18:05 pm
content: based on the offical data sheet.RDS(on) max(@ VGS = 10V) 3.5 m(@ VGS = 4.5V) 4.5 mbut even if that was the case, why is it the bms module which cost me a whopping 81c, is not even warm passing close to the same current?

author: edavid
author_rank: Super Contributor
timestamp: December 16, 2024, 11:53:13 pm
content: Quote from: littlebill on December 16, 2024, 11:18:05 pmNo, I mean what is the measured VGSin your circuit?QuotePlease post your schematic.

author: littlebill
author_rank: Regular Contributor
timestamp: December 21, 2024, 03:23:55 am
content: To close this out since I asked for the post to be deleted.The Mosfets were fake. I ordered a set from Mouser with 1.5mohm RDS, I went from 295F at 10A to 5 degree's over ambient.

author: eTobey
author_rank: Super Contributor
timestamp: December 21, 2024, 06:39:05 am
content: No, dont delete it! Its valueable information for others!Did you write a negative review?Do you also see 5 ratings of a average of 5 stars?
MOSFET identify / substitute? - Page 1
Forum section: electronics / beginners

author: ssashton
author_rank: Frequent Contributor
timestamp: April 22, 2022, 12:30:54 pm
content: Hi,I have some stepper motor drivers which were sold as supporting 60V rails. I need more but they are not sold anymore. There is another that uses the same driver chip TMC2160 but has a lower voltage rating. It seems to me the main reason is probably just the choice of output mosfets.The mosfet used on the 60V version is SMD and labelled 14006NHThe mosfets on the lower rated device are WSP4984 -https://embeddedtronicsblog.wordpress.com/2020/06/24/tmc2160/Can anyone identify the 14006NH device so I can confirm it's voltage rating and second, could I get some pin compatible suggestions to up-rate the WSP4984 to 60V capable?

author: ssashton
author_rank: Frequent Contributor
timestamp: April 22, 2022, 12:43:43 pm
content: Never mind everybody, I found an alternative product!

author: wraper
author_rank: Unknown
timestamp: April 22, 2022, 12:44:35 pm
content: https://www.mouser.com/datasheet/2/408/TPN14006NH_datasheet_en_20140107-1140146.pdf60V rating is quite optimistic considering that max voltage for MOSFET is 60V.

author: ssashton
author_rank: Frequent Contributor
timestamp: April 22, 2022, 12:52:09 pm
content: Thank you!Will the fact it's switching inductive loads be related to the VDSS, or is it really just about rail voltage?
MOSFET K2611 Toishiba - DMM Test - Fail?? - Page 1
Forum section: electronics / beginners

author: SgtRock
author_rank: Unknown
timestamp: February 26, 2012, 10:42:51 pm
content: Greetings EEVBees:--I am using a Fluke 87 DMM (set to diode mode) to check a K2611 MOSFET.1) I connect the Neg. lead from the DMM to the Source.2) I then connect the Pos. lead to the Drain.Result: Open Circuit, No conduction.3) I the touch the Pos. lead to the Gate.Result: Open Circuit, No conduction.4) I then reconnect the Pos. lead to the Drain.Result: Circuit conducts for about 4 seconds starting a 0 Volts and rising to about 2.8 Volts. Then, Open Circuit, No conduction.--Question. Am I correct that the MOSFET should stay on until I touch the Gate.--See below attached datasheet PDF and a picture of the MOSFET."Three weeks in the lab will save you a day in the library every time"R. Stanley Williams 1951 -Best RegardsClear Ether

author: IanB
author_rank: Super Contributor
timestamp: February 26, 2012, 11:43:31 pm
content: I think your MOSFET is behaving as expected.Drain to source will be high resistance until you turn the MOSFET on.The gate will always be open circuit as it has no electrical path to the rest of the device. It is insulated.When you touch the positive lead to the gate you charge it up and turn on the FET for a short while until the charge dissipates. That explains the 4 seconds of on time.If the gate was perfectly insulated it would stay on forever once you charge it up, but nothing connected to the outside world is that good of an insulator. Just the dampness in the air will be enough to conduct the charge away through the device pin.

author: SgtRock
author_rank: Unknown
timestamp: February 27, 2012, 07:35:47 pm
content: Dear IanB:--Thanks for the good information."He was born ignorant, and has been losing ground ever since."Fred Allen 1894 1956Best RegardsClear Ether

author: Tube_Dude
author_rank: Regular Contributor
timestamp: February 27, 2012, 11:30:58 pm
content: Usually, I prefer an old school analog multimeter, for this test...
MOSFET load balancing in inverter? - Page 1
Forum section: electronics / beginners

author: hermitengineer
author_rank: Regular Contributor
timestamp: October 28, 2020, 05:43:57 am
content: I'm looking at an inverter that fails by giving low power output. I discovered that among the 8 internal 30A fuses, 4 were blown. Looking at the 8 MOSFETs in the input stage, 2 seem to be shorted out... at least, gate-source is a short. The question then, is whether replacements need to be matched in the inverter like they do in audio amps. From the reverse-engineered schematic, maybe not since they are connected directly in parallel without even a small resistor.Here's a schematic of one of the input stage components. The 4 are connected in series along the transformer secondaries to multiply the voltage for the rectifier.

author: fourtytwo42
author_rank: Super Contributor
timestamp: October 28, 2020, 10:30:22 am
content: No you don't have to match them exactly however the switching characteristics and RDSon have to be much the same else they will not share equally, just replacing them with the same type from the same vendor would be adequate.Moving on from your question it might be a good idea to test the remainder of the circuit with the remaining working devices to ensure there isn't anything else wrong at a suitably low power.
MOSFET matching for PFC section of ATX PSU - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 01, 2018, 02:29:17 pm
content: For a Corsair CX600W (600W)PSU I'm fixing, I need to match 2 MOSFET's (so far). They are K18A60V so 18A and 600V rated.I'm going to use an LM317 circuit to test them for G-S voltage and S current.But what input voltage and current should I be aiming for? I can easily hook up, upto 37V(max for typical LM317 circuit)But I have no easy or safe way to get anywhere near what the PSU provides to them.

author: Paul Price
author_rank: Super Contributor
timestamp: March 01, 2018, 09:46:43 pm
content: Why would you think they would need to be matched? I doubt that they would need to be matched, this would be costly to mfg.
Mosfet Not turning Off fast - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: April 21, 2019, 03:46:00 pm
content: I am trying to PWM a Mosfet STP55NF06, gate resistor is 2.2ohm and drain voltage is 12V.The gate is being driven by a driver MIC4422.The driver has a supply voltage of 12V too. And the pulse frequency is 250Khz with duty cycle 50%.I want to eventually drive a inductive load but currently testing out with a 1K resistor.While probing the drain voltage with a scope I find that the turn on is razor sharp but turn off is like i ramp.I have attached a picture. I hope someone can shed some light on this.Regards,

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: April 21, 2019, 04:10:15 pm
content: Ok, I put a stronger load like 150ohm and the turn off now seems sharper not razor sharp though.

author: ogden
author_rank: Super Contributor
timestamp: April 21, 2019, 05:28:18 pm
content: Quote from: ZeroResistance on April 21, 2019, 04:10:15 pmMOSFET has significant Drain-Source capacitance - that's why you see sawtooth waveform. Waveform quite well agree with t=RC for 1KOhm and 1300pF (input capacitance of mosfet you use). Even with 150 Ohms RC constant (65% of 12V reached) is quite long 0.195 microseconds. Test with 5A current or so - then capacitance of transistor itself does not play significant role anymore.

author: David Hess
author_rank: Super Contributor
timestamp: April 21, 2019, 06:48:37 pm
content: Exactly, the load impedance is too high. Either use a lower load impedance or use a transistor with lower capacitance.
Mosfet output protections - outdoor applications - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: June 06, 2019, 05:47:36 am
content: HelloI wanted to build a 24V DC + 1-Wire network for outdoor applications. The wires could be quiet long, like 30m.I'm planning to use a PCB with MOSFET on it to drive on and off the different channels (actually I'm using TPS2482 efuses).Now the question I have is about the DC protections I needed to add on the output of the mosfets. In case of lightning I could imagine that there could be huge amount of overvoltage induced in those cables.If I add GDT/MOV/TVS on the output of the mosfet I think it would be ok in the case of the mosfet is on. The overvoltage passes to the ground line and it would be at max be at the same potential as the V+ (which is connected through the mosfet to the circuit).Now, if the output of the mosfet is switched off, the same will happen, but because the V+ isn't connected to the circuit anymore (mosfet off), the ground could be at a higher potential as the V+ (PCB side). In other words the components will probably burn.I'm wrong?How should I protect the output of the mosfets???Thank you

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 06, 2019, 06:50:50 am
content: Just stick on a TVS (say SMAJxxA size), to protect against overvoltage. Lightning induced surge over that length shouldn't be a big deal, assuming there isn't a ground reference at the far end that is.Tim
Mosfet performs below my expectations. - Page 1
Forum section: electronics / beginners

author: liviu.gelea
author_rank: Contributor
timestamp: December 15, 2020, 02:44:17 pm
content: I think I'm missing some knowledge about how mosfets behave.I have the following circuit using anIPP029N06NThe problem is I expected the voltage drop over DS to be waaay smaller than the 3V it is.Now my current understanding is that at 5V through the gate, the source-drain should act like a few miliohm resistor but even at 15v I still get a 3.2v drop.Could someone please shed some light as to what I'm wrong about? Initially I paired 10 of these in parallel hoping to drive enough amps to weld nickel strips. I ended up buying a working device insteadThanks

author: wraper
author_rank: Unknown
timestamp: December 15, 2020, 02:51:33 pm
content: You cannot use a MOSFET like that. It will not fully open, as once current starts flowing through it, GS voltage will drop. If you place a resistor in series with drain, not source, it will work properly.QuoteAnd there will be way less than 5V with your circuit.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 15, 2020, 02:51:42 pm
content: MOSFET is controlled by Vgs (voltage between gate and source).When current is flowing through your resistor, what is your Vgs?

author: liviu.gelea
author_rank: Contributor
timestamp: December 15, 2020, 03:07:53 pm
content: OH, I'm terrible. Every time I read "Vgs" I thought about the potential of the gate relative to the ground, which in this case is tied to DRAIN, not source.Thanks a lot for your time.PS I'm surprised anything turned on since my Vgs was basically 0.

author: wraper
author_rank: Unknown
timestamp: December 15, 2020, 03:12:06 pm
content: Quote from: liviu.gelea on December 15, 2020, 03:07:53 pmIt was not 0, It was slightly above VGS(TH)
MOSFET power calculation - Page 1
Forum section: electronics / beginners

author: r4r
author_rank: Contributor
timestamp: December 19, 2019, 03:07:25 pm
content: Hello everyone!I need to limit current with MOSFET IRF4905PBF to -20A. Datasheet says max current -70A and Rds(on) is 0.02Ohm.Not really sure how to calculate Rds and power dissipation for -20A and, let's say, -18V? Vgs = -4.7V.Rds = 18/20 = 0.9 OhmP = 20^20*0.9 = 360W?Is it correct?

author: Ice-Tea
author_rank: Super Contributor
timestamp: December 19, 2019, 03:31:39 pm
content: Your calculation is right but you took a bit of a detour. Just U*I works just fine.Also: forget about dissipating 360W in that FET. It has a Junction-to-Case thermal resistance of 0.75°C/W. So, your die will sit at 270°C above ambient even if you cool the case with a generous helping of pixie dust and hail marys.

author: r4r
author_rank: Contributor
timestamp: December 19, 2019, 06:18:55 pm
content: Thank you, Ice-Tea! =)Maybe I should use two IRFs in parallel?Don't have any other idea...

author: Ice-Tea
author_rank: Super Contributor
timestamp: December 19, 2019, 06:59:11 pm
content: I suggest you look into a topology that doesn't have you dissipate 300W. Perhaps you should start by telling us exactly what you are trying to achieve..

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 19, 2019, 10:26:43 pm
content: A switching current limit will dissipate a whole hell of a lot less power... but isn't much of a beginner project.Does it have to be continuous, or can it be intermittent? Controllers like TPS2491 can be used to handle this, with a constant-power characteristic that optimizes on-time within thermal limits. You still only get 10s of ms though.Tim
mosfet problem - Page 1
Forum section: electronics / beginners

author: LagStorm
author_rank: Newbie
timestamp: September 23, 2022, 09:41:49 pm
content: Hello, I had a problem with a TV power supply, an ME4542-M943 mosfet exploded, but I couldn't find the reference, does anyone know where I could find it, or what to replace it with?

author: Zero999
author_rank: Super Contributor
timestamp: September 23, 2022, 10:14:35 pm
content: Just search for ME4542. The rest is just the package date code.https://www.force-mos.com/uploads/product/tw/ME4542%20V4.1_SPEC.pdfThey're available on ebay, but I wouldn't know whether they're real or fake. My guess is second hand is most likely. If the price and risk is acceptable, go for it.

author: LagStorm
author_rank: Newbie
timestamp: September 24, 2022, 02:31:45 pm
content: Thank you for your help I will order some
MOSFET question - Page 1
Forum section: electronics / beginners

author: rexxar
author_rank: Frequent Contributor
timestamp: February 14, 2014, 04:24:56 am
content: I'm designing a circuit that will drive an RGBW LED from a single LiPo. I'm using MOSFETS to drive them with a PWM signal. The FET I chose from Mouser (I've not ordered them yet) is aPSMN022-30BL,118, and it says it operates at logic level. If I'm reading fig. 6 on the datasheet correctly (p.6), it will pass ~7A at 3Vgs?My question is, will this be suitable for driving about 500mA from a single LiPo cell? I've got about 2 sq in of PCB heatsinking for four FETs. I'm concerned that I won't be able to drive them into saturation and heat will be an issue. (That's all the space I could afford; it's a very small board)I only understand the basics of how MOSFETs work, and I don't understand a lot of the values in the datasheet. Advice on this project and recommended reading for MOSFETs would be greatly appreciated.

author: Kremmen
author_rank: Super Contributor
timestamp: February 14, 2014, 07:26:33 am
content: Checking the same datasheet (Fig 9) one can estimate the on-state resistance @3Vgs to be something around 100 mohm or so (the value is outside the chart making it a bit hard to estimate. The dissipation @500 mA would be just 25 mW so you should have no problems even though the switch is not properly in saturation.
Mosfet Recovery Time requirements - Page 1
Forum section: electronics / beginners

author: rentner
author_rank: Regular Contributor
timestamp: May 15, 2013, 11:30:32 am
content: Hello folks. I will keep that very simple. I want to switch a mosfet at 200kHz with PWM as exact, as possible. I would like to use a mosfet with a recovery time of 570ns. Is this acceptable for 200kHz with PWM? (It should not be distorted more than 2% under ideal gate driving conditions.)PW will reach from 1% to 95%.Is a recovery time for that of 570ns enought, or what would you recommend?Thanks.

author: Kremmen
author_rank: Super Contributor
timestamp: May 15, 2013, 07:53:56 pm
content: Recovery time? MOSFET? Err.. that does not compute...FETs don't have a recovery time as such, instead they have gate charge and apparent gate capacitance that you need to charge/discharge. The gate drive circuit determines the timing to a large extent, subject to the properties of the FET naturally.In itself 200 kHz is an entirely reasonable switching requency but you need to pay attention to the specs of the FET you plan to use. Properties like gate charge should be below average already. If your application operates by hard switching there will be inevitable power losses during switching events. The alternative would be some kind of resonant or semi-resonant zero voltage or current switching but that is advanced stuff at these frequencies.

author: rentner
author_rank: Regular Contributor
timestamp: May 16, 2013, 01:27:59 pm
content: I built a gate driver, that would charge a Gate with 1uF capacity so fast, that at 100kHz it still is a very clean square wave.Well, I need to charge or discharge the Gate very fast. But anything else? Is that enough?

author: Kremmen
author_rank: Super Contributor
timestamp: May 16, 2013, 06:56:30 pm
content: If your gate timing is OK then you are basically done. You sould be aware though, that overdriving the gate heavily is prone to cause oscillations in the 10s to 100s MHz range. These have a nasty tendency radiate as EMI into the environment and cause other kinds of unpleasantness as well. So you might want to watch out for that.

author: SeanB
author_rank: Super Contributor
timestamp: May 16, 2013, 07:53:56 pm
content: You probably will need a ferrite bead on the gate or drain lead to suppress oscillations with very fast drive. Will not damp totally but can stop it killing the device instantly.
MOSFET Regions of Inversion - Page 1
Forum section: electronics / beginners

author: fourierpwn
author_rank: Regular Contributor
timestamp: April 10, 2017, 06:02:45 am
content: Hi all,I am trying to wrap my head around the concept of inversion regions in a MOSFET; weak, moderate, strong.I think that I get the general gist of them however all of the theory that I have read is fairly heavily math/physics involved and I am losing my train of thought.Is someone able to explain these regions in laymen's terms for me?

author: danadak
author_rank: Super Contributor
timestamp: April 10, 2017, 10:32:37 am
content: Quite a few videos, applets, on web and Youtube describing MOSFEToperation, inversion.....Regards, Dana.
Mosfet Replacement What to Look For? - Page 1
Forum section: electronics / beginners

author: SteveO
author_rank: Newbie
timestamp: February 27, 2013, 11:09:11 pm
content: HiSome of you might have seen my thread on Desoldering the Transistor. I need to ask some more Advice. I need to look for a replacement for the AOD472 that I buggered up.What are the important matching elements I need to find on a replacement? I am very new to Mosfet in general so any simple advice will be welcome.Full Data Sheethttp://www.alldatasheet.com/datasheet-pdf/pdf/135810/AOSMD/AOD472.htmlThanksSteveO

author: Kremmen
author_rank: Super Contributor
timestamp: February 28, 2013, 07:10:50 am
content: Apart from the maximun voltage, current and power dissipation, you should consider the following, not necessarily in this order:- Vgs (gate-source voltage) needed for turn-on. Especially important in switching applications to ensure the device is fully conducting. There are logic-level fets that turn on with lower Vgs than the "regular" ones.- Rdson (main channel resistance when fully on) This figure defined the minimum achievable power loss during saturated conduction- Qg (total gate charge) - as the name says, this defines the charge you need to pump back and forth to fully charge / discharge the gate. This cycle must repeat once for every switching cycle. Recalling that electrical current is nothing but movement of charge, you get from this to the gate current when you know the switching frequency.These will get you a long way. Then there are more intricate details like subdivision of gate charge into separate components Qs and Qd, and similar. But when you get so far that you need that info, you will already know their significance.

author: ftransform
author_rank: Frequent Contributor
timestamp: February 28, 2013, 11:40:04 am
content: lead free chirstmas tree? who would have thought