pmos won't switch off cleanly

Started by panfilero in sci.electronics.design9 years ago 20 replies

I'm trying to switch a p-channel mosfet on and off, I've hooked up a functi= on generator to the gate, it's going from 0 to 10V, I've got the...

I'm trying to switch a p-channel mosfet on and off, I've hooked up a functi= on generator to the gate, it's going from 0 to 10V, I've got the Source pul= led up to 10V, and a load resistor of 5k on the Drain... it turns on quick!= I see my full voltage across the load, no problem... ohhhh but that turn o= ff is ugly... and it starts acting this way at around 10Hz, I've driven it = to 200kHz ...


Fast buffer idea

Started by bitrex in sci.electronics.design5 years ago 133 replies

Diamond buffers are kind of cool, emitter feedback makes them linear and they don't have much phase shift, but they kind of suck balls whenever...

Diamond buffers are kind of cool, emitter feedback makes them linear and they don't have much phase shift, but they kind of suck balls whenever you want to actually move appreciable current with them which unfortunately is exactly what you'd want to do with a buffer. I came up with this thing that uses a sort of MOSFET-BJT Sziklai pair input-thing to drive boosting transistors to pump m...


opamps coming off the rail

Started by John Larkin in sci.electronics.design9 years ago 27 replies

I need to drive a mosfet in current-sink mode. It's similar to...

I need to drive a mosfet in current-sink mode. It's similar to this circuit https://dl.dropboxusercontent.com/u/53724080/Circuits/Current_Sources/Mirror2.JPG but V- will be ground and I'll run the opamp off +8 or +10 or something, whatever drive the fet needs to sink 150 amps. I'd prefer to not have a negative power supply. At zero requested current, I want the current to be really...


Is This Spice Model Accurate?

Started by rickman in sci.electronics.design7 years ago 15 replies

This model for a PMOSFET shows VTO=1.00. The data sheet shows VGS(th) as -1.0 to -0.45 volts. I'm guess these are two different specs? One...

This model for a PMOSFET shows VTO=1.00. The data sheet shows VGS(th) as -1.0 to -0.45 volts. I'm guess these are two different specs? One is where the current is at a specified level and the other is where the current starts to change from the cut off condition? Here is the model for this part. *SRC=DMP2240UDM;DI_DMP2240UDM;MOSFETs Enh;20.0V 2.00A 0.150ohms Diodes Inc MOSFET .M...


physics question

Started by John Larkin in sci.electronics.design9 years ago 19 replies

If one had a power mosfet with really hunky source and drain connections, would the thermal conductivity from source to drain depend on the...

If one had a power mosfet with really hunky source and drain connections, would the thermal conductivity from source to drain depend on the gate voltage? -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom t...


Hacking a depletion MOSFET model

Started by Phil Hobbs in sci.electronics.design3 years ago 48 replies

The LND150 model predicts IDSS of about 2.4 mA, whereas the actual parts cluster very tightly around 1.6 mA. Here's the model--what should I...

The LND150 model predicts IDSS of about 2.4 mA, whereas the actual parts cluster very tightly around 1.6 mA. Here's the model--what should I adjust to fix it? .MODEL LND150 NMOS (LEVEL=3 RS=150.00 NSUB=5.0E13 +DELTA=0.1 KAPPA=1.O TPG=1 CGDO=2.1716E-12 +RD=40.0 VTO=-2.0 VMAX=1.0E8 ETA=0.1 +NFS=6.6E10 TOX=1.0E-7 LD=1.698E...


Unknown MOSFET logo

Started by Phil Hobbs in sci.electronics.design2 years ago

Hi, all, I'm trying to identify this part, which is probably an N-FET: Octopart, LCSC, and the usual datasheet sites come up...

Hi, all, I'm trying to identify this part, which is probably an N-FET: Octopart, LCSC, and the usual datasheet sites come up dry. Anyone recognize the logo and/or part number? Thanks Phil Hobbs (Sorry for the multipost--I've been pitching in on the basics group for a bit) -- Dr Philip C D Hobbs Principal Consul


an Alibaba seller comes through, again.

Started by Winfield Hill in sci.electronics.design3 years ago 18 replies

In 2012 Hitachi introduced the RJK6024, a small-die super-junction low-capacitance DPak 600-volt MOSFET, and its datsheet plot showed Crss =...

In 2012 Hitachi introduced the RJK6024, a small-die super-junction low-capacitance DPak 600-volt MOSFET, and its datsheet plot showed Crss = 0.65pF at 100V. I badly wanted a bunch for making faster high-voltage amplifiers. But I could never get any in the US, not even a sample. Eventually when I learned that Hitachi Renesas had discontinued the part, I thought perhaps they had ne...


Faux MOSFET... Behavioral Modeling

Started by Jim Thompson in sci.electronics.design8 years ago 5 replies

For sometime now I have been trying to build a behavioral model of logic gates that was consistent with real-world behavior when mixed into an...

For sometime now I have been trying to build a behavioral model of logic gates that was consistent with real-world behavior when mixed into an Analog environment. (Existing logic models, such as those in PSpice and LTspice are state machines and do not behave properly when used for Analog applications, such as when you build a crystal oscillator around a 74HCU04.) So I now invite you to ...


SOT-23 at 1.5 watts

Started by John Larkin in sci.electronics.design5 years ago 22 replies

I'm designing an LDO to drop 1.8 volts to 1.0, to power an FPGA core. We have a SOT23 n-channel mosfet in stock, IRLML6344. IR rates it at 1.3...

I'm designing an LDO to drop 1.8 volts to 1.0, to power an FPGA core. We have a SOT23 n-channel mosfet in stock, IRLML6344. IR rates it at 1.3 watts power dissipation, and I was skeptical, because a SOT23 is usually good for maybe 300 mW and IR is notoriously optimistic in their power specs. But it can dissipate 1.5 watts somehow. https://dl.dropboxusercontent.com/u/53724080/Parts/Fets...


High power 2kHz DC-DC with iron toroid - success with MOSFET drivers!

Started by P E Schoen in sci.electronics.design9 years ago 1 reply

I posted awhile back about a DC-DC converter I built which took 12V from = a=20 battery and boosted it to 320VDC for a VFD, and I was able to...

I posted awhile back about a DC-DC converter I built which took 12V from = a=20 battery and boosted it to 320VDC for a VFD, and I was able to use it to=20 drive a small tractor, as shown in my YouTube video:=20 http://youtu.be/y0qWY4bVnEA. It provided up to about 200-250 watts, = assuming=20 12 volts and 15-20 amps. It's a 2HP motor so this is barely tickling it. Since then, I made a moni...


AoE x-Chapters, 45 years of power MOSFETs

Started by Winfield Hill in sci.electronics.design2 years ago 23 replies

A new section from the AoE x-Chapters book, for you to read, enjoy, and make comments. A 30-Year MOSFET Saga, The next 15 years, and Four...

A new section from the AoE x-Chapters book, for you to read, enjoy, and make comments. A 30-Year MOSFET Saga, The next 15 years, and Four kinds of power MOSFETs. https://www.dropbox.com/s/0qh8dxgielrkqvq/chap-3x.11_MOSFET-saga_2019-07-19.pdf?dl=0 -- Thanks, - Win


SiC

Started by Tim Williams in sci.electronics.design10 years ago 4 replies

Has anyone used SiC semiconductors before -- JFETs, MOSFETs or schottkies? Specs look good on Cree's 20A, 1200V, 80mohm MOSFET -- better than...

Has anyone used SiC semiconductors before -- JFETs, MOSFETs or schottkies? Specs look good on Cree's 20A, 1200V, 80mohm MOSFET -- better than silicon, and at that voltage, the $50 price tag isn't even that bad compared to the three $15 silicon MOSFETs you'd need to achieve the same conduction losses. Switching losses in the datasheet aren't that great for high frequency use (> 100kHz),


Spice model suggestions, ping Jim?

Started by Clifford Heath in sci.electronics.design8 years ago 3 replies

Jim, Since you said you were interested in suggestions for Spice models, so here's two: SA612/SA602. There are models around, but I have...

Jim, Since you said you were interested in suggestions for Spice models, so here's two: SA612/SA602. There are models around, but I have no way of knowing how good they are. BF904R. This strange dual-gate MOSFET is NLA, but was the secret sauce in some interesting RF front-ends because of its ability to run very high gain or attenuation (+-70dB in one example I'm aware of) with ...


PCB transmission line transformer

Started by John Larkin in sci.electronics.design7 years ago 54 replies

We've used transmission-line transformers to drive mosfet gates. We've wound them from micro-coax on ferrite toroids, with the shield being...

We've used transmission-line transformers to drive mosfet gates. We've wound them from micro-coax on ferrite toroids, with the shield being the primary and the inner conductor the secondary. Sub-ns speed and low leakage inductance. But it's labor intensive. So I was thinking about doing it on a multilayer PCB, like a 6-layer. Layers 1/3/5 could be one to three layers of spiral trace, pr...


capacitor gets hot in a HF-HV resonant circuit

Started by blisca in sci.electronics.design6 years ago 28 replies

Hi i was asked to help some friends in a task that is unusual for me: I have to generate a 100 Vpp -150 KHz ringing on a single turn of a...

Hi i was asked to help some friends in a task that is unusual for me: I have to generate a 100 Vpp -150 KHz ringing on a single turn of a transformer secondary. I generate an adjustable PWM with a microcontroller,then a driver drives a N MOSFET connected to VDD via a couple of turns(the primary of the transformer),paralleled by a capacitor** With a pulse width of about 7us i have ...


Dumb LTSpice question - subckt model

Started by Anonymous in sci.electronics.design7 years ago 12 replies

I've never used a mfr model that was a subckt before; I've always added the .MODEL to the LTSpice library file, or edited an existing...

I've never used a mfr model that was a subckt before; I've always added the .MODEL to the LTSpice library file, or edited an existing device. This Vishay MOSFET has a more complex model though, and she ain't loadin' Jim. LTSpice says it can't find the model for M1. I even tried putting the definition right in the .asc, still no joy. I followed the LTSpice help info, as best I could. A...


Soldering to glass

Started by Piotr Wyderski in sci.electronics.design2 years ago 22 replies

I have recently conducted some research on binding SMD components with glass and ceramic substrates using pure indium and indium alloys. The...

I have recently conducted some research on binding SMD components with glass and ceramic substrates using pure indium and indium alloys. The results are very satisfactory, and the technique may find some applications in HV and high power density solutions. One can directly solder a MOSFET to a ceramic heatsink or a string of HV resistors to an insulating glass plate without prior metalis...


inductor for HV flyback supply

Started by Winfield Hill in sci.electronics.design5 years ago 71 replies

I've created all kinds of HV circuits in the last 5 years,** and each one needs an external HV supply. So I really need some simple...

I've created all kinds of HV circuits in the last 5 years,** and each one needs an external HV supply. So I really need some simple HV-supply circuits to plop onto these PCB's to make them self-sufficient. Today's circuit is a basic flyback, to convert a 12V,1A wallwort source to 500V max, at 5-10W load. I used a UC3843B running at 100kHz driving a MOSFET switching a 47uH indu...


MOSFET selection for boost converter problem

Started by John Nagle in sci.electronics.design5 years ago 30 replies

I've been working on a power supply for antique Teletype selector magnets. These need 120VDC 60mA for the first 2ms or so of each bit time,...

I've been working on a power supply for antique Teletype selector magnets. These need 120VDC 60mA for the first 2ms or so of each bit time, but the sustain voltage needed is only 3-4V. So I've built an isolated boost supply and interface board, all powered from a USB port. The whole project is on Github: https://github.com/John-Nagle/ttyloopdriver where there's an explanation of how...