Questions tagged [gate-driving]

MOSFET and IGBT gate driving

32
votes
6answers
10k views

Designing a *linear* MOSFET driver stage

I'm looking for a MOSFET driver circuit that can be placed between an op-amp and a power MOSFET to operate the transistor as a linear amplifier (as opposed to a switch). Background I'm developing an ...
23
votes
2answers
33k views

Criteria behind selecting pwm frequency for speed control of a dc motor?

I'm working on a speed control circuit for a brushed dc motor (24v, 500rpm, 2A, 4kgcm). The main components that I plan to use are PIC16f873, 4n25 optocoupler, IRFZ44N MOSFET, BY 500 - 800 diode(for ...
15
votes
6answers
3k views

Is it okay to use a MOSFET in its resistive region with a heat sink?

Using transistors in with limited gate (or base) voltage will make them limit current, which will introduce a significant voltage drop across the transistor, causing it to dissipate energy. This is ...
14
votes
2answers
33k views

Bootstrap circuit for high-side MOSFET driver

I am very familiar with the operation of bootstrap drivers on MOSFET driver ICs for switching an N-channel high-side MOSFET. The basic operation is covered exhaustively on this site and others. What ...
12
votes
2answers
9k views

What is MOSFET gate drive capability and why do I care about it?

Someone told me that this circuit has "poor gate drive capability": simulate this circuit – Schematic created using CircuitLab What exactly does that mean? I tested it with an LED as a load ...
12
votes
2answers
3k views

What is the difference between driving a MOSFET gate and an IGBT gate?

Can I use an suitable IGBT gate driver for driving the MOSFET, and vice versa? Which parameters (threshold, plateau, and turn on voltage ratings, gate capacitance, etc) must be the same for this ...
9
votes
4answers
15k views

How can I slow down the switch time of a MOSFET?

I have an NMOS that is switching too fast for my application. Into the gate I am sending a logic-level square wave (PWM). Unfortunately for me, as expected, the output is also a near square wave. How ...
9
votes
3answers
2k views

Paralleling Mosfets: Can I use a common gate resistor, or do I have to use a separate one for each mosfet?

When calculating gate resistor for a single mosfet, first I model the circuit as a series RLC circuit. Where, R is the gate resistor to be calculated. ...
7
votes
3answers
3k views

Do we need a resistor to discharge capacitor of MOSFETs while connected to MCU?

I have an STM32 MCU at home. I was thinking of controlling a load with this MCU and a MOSFET. Let's assume this is my circuit: In this circuit, we use a resistor (R2) to discharge the gate of the ...
6
votes
2answers
1k views

Should I gate SCRs on when reverse-biased?

I've been told that it's a bad idea to gate SCRs on when reverse-biased. Is that accurate? I'm reasonably confident that the SCRs won't actually conduct reverse-biased whether gated or not; are there ...
5
votes
2answers
2k views

Why is my power MOSFET heating up when on?

I'm switching a 12V 500mA resistive load (LED strip) with a IRF540 MOSFET and it's getting very hot when it's on and conducting. This confuses me as MOSFETs are ...
5
votes
4answers
675 views

Constant current source with MOSFET, OPAMP and Instrument Amp

UPDATE Based on the information from everyone answering below, I have modified my circuit and the oscillation has completely vanished! I started performing small modifications in order of easiest to ...
5
votes
2answers
8k views

Is it possible to use P-MOSFET at the floating high side of a MOSFET driver?

I need to use a MOSFET driver in my circuit. I have read some MOSFET driver datasheets. As far as I have seen, always an N-MOSFET is used at the high side. For example, consider FAN7842. Typical ...
5
votes
2answers
1k views

Does this use of IR2183 as high-side n-channel gate driver work?

I'm building a switching power supply taking 12V to 19V at 3A max out. I've already built one of these using a Schottky diode for the rectifier, but this time I'm thinking of trying a high-side-...
5
votes
1answer
102 views

How to speed up level shifter?

I have a level shifter that uses a transistor to control the gate of a high voltage P-channel MOSFET, like this: simulate this circuit – Schematic created using CircuitLab This is designed to ...
4
votes
3answers
17k views

Bootstrap circuit function

I had some question about the bootstrap capacitor on gate driver. First, the bootstrap capacitor is used because the voltage on the high side drivers gate need to be about 10-15 volts higher than the ...
4
votes
3answers
6k views

Driving high and low inputs of a MOSFET driver with a single PWM signal

(A typical circuit from FAN7390 datasheet.) I have high-side and low-side MOSFETs to drive. I read dozens of MOSFET driver datasheets, all of them have two separate inputs for controlling high and ...
4
votes
2answers
103 views

Mosfet gate driver have no direct connection to ground

This picture shows some part of a high frequency (about 250kHz) MOSFET gate driver circuit.I searched for various types of gate drivers in google and didn't encounter anything like this. Can someone ...
4
votes
2answers
7k views

Internal structure of MOSFET gate driver integrated circuts

As far as I know, a typical MOSFET is driven by a circuit like below. I read several MOSFET driver IC datasheets. It looks like they have a more complicated internal structure. For example, the ...
4
votes
2answers
232 views

Level shifted PMOS driver operation

simulate this circuit – Schematic created using CircuitLab Having some confusion this gate driver. It can be found in Design and Application Guide For High Speed MOSFET Gate Drive Circuits. ...
3
votes
2answers
1k views

Why do MOSFET drivers need so much current?

I'm using a MOSFET driver to drive a 6 MOSFET H-bridge, with a 40V supply. At 25 KHz, the driver gets very hot, almost too hot to touch. The MOSFETs have a gate charge of 350 nC. Why does it take so ...
3
votes
2answers
2k views

AC coupled gate drive

I am trying to get a MOSFET/IGBT driver to work for almost a year. The last efforts utilizing a bipolar Totem pole driver failed without mercy. For some time I studied alternatives and came to AC ...
3
votes
1answer
6k views

MOSFET Gate-Source protection question

I have seen different schemes in the three phase motor inverter design when people try to protect gate-source from high voltage as shown in the picture. I understand the usage of zener diode to limit ...
3
votes
2answers
371 views

MOSFET Miller effect: length of the gate voltage flat area

As per Miller effect the gate voltage stops to grow at the threshold level until some certain moment: This can be explained as the drain to gate capacitance drives current through the gate. However - ...
3
votes
4answers
305 views

Power MOSFET blew up when increased duty cycle from 5% to 10%

First, these are the components I'm using on my PCB, click on them to see the datasheets: U7: Infineon 1EDI60N12AF MOSFET Gate driver Q6: Infineon IRF250P224 Power MOSFET D5: Fairchild (ON ...
3
votes
1answer
554 views

Half Bridge Gate Drive Transformer - Extra winding?

I've been experimenting on a lot of half-bridge-based PC PSU schematics. There's one thing I cannot understand: As can be seen from above, there's an extra winding in series with the high side ...
3
votes
2answers
361 views

What does this IGBT data sheet mean by “transient” gate voltage?

I'm using IXGH45N120 to discharge some capacitors. The gate voltage is derived from the capacitor voltage, through some resistors and a zener. The circuit has worked fine for a long time, many ...
3
votes
1answer
2k views

MOSFET gate transformer noise issue

I have built the following circuit. I am using a microcontroller via 3 transistors to drive the transformer and applying a 50% duty cycle 15kHz PWM signal. With 18V applied to the VIN header input, I ...
3
votes
0answers
56 views

Alternate uses for Gate Driver - Driving a Load without External IGBT or FET

What issues would one encounter by using a gate driver IC to directly drive a load instead of using it to drive transistors? For consideration would be the very affordable Infineon 2EDN752x series ...
3
votes
1answer
2k views

Purpose of anti-parallel diodes in isolated gate driving circuit?

I've come across this high voltage 'modulator' circuit and the MOSFET gate drive circuit is shown below. The floating wire on the bottom connects to a duplicate of this circuit at the MOSFET drain (...
2
votes
5answers
6k views

Microcontroller incapable of driving MOSFET

I am using attiny45 microcontroller for switching MOSFET at 40kHz. I have the following circuit set up: simulate this circuit – Schematic created using CircuitLab If I measure the signal ...
2
votes
2answers
717 views

IGBT transistor with auxiliary emitter

Recently I discovered, that some IGBT transistors in IGBT modules have the second pin for an emitter, called auxiliary emitter. In the picture above 2nd and 4th pins are auxiliary emitters. This is ...
2
votes
1answer
139 views

Why is it better to use this Opto-coupler to drive the gate of a FET than using other methods?

My question is what significant advantage does using this HCPL3180 opto-coupler have to drive the gate of an FET over using other methods, such as using an op-amp or BJTs ??? and also does it have ...
2
votes
1answer
313 views

How to detirmine if I need a gate driver for MOSFET or not?

I want to design a BLDC motor controller and I am still collecting some info about the components that I will use, of course main components will be MCU and MOSFETs. I have seen some designs that use ...
2
votes
2answers
2k views

Is it safe to “top up” bootstrap capacitors using a charge pump?

This document from TI describes a method to allow use of bootstrapped N-Channel MOSFETS at high duty-cycles, by keeping the bootstrap capacitor "topped up" with an external charge pump, separate from ...
2
votes
3answers
1k views

Why gate drive transformer is not connected directly to the gates in this App Note?

Here’s a circuit from TI App Note SLUA323, which shows a synchronous rectification in a current doubler circuit. U2 is a gate driver. Transformer T2, which looks very much like a gate drive ...
2
votes
3answers
1k views

Boost converter for high side Mosfet

I recently came across an article explaining how to drive a high side MOSFET using a "separate isolated power supply whose ground and the ground of the MOSFET-based circuit are isolated". However ...
2
votes
2answers
328 views

Gate Driver IC question?

Refer to this Question: MOSFET Gate Driver Simulation Problem My Gate Driver datasheet: http://www.irf.com/product-info/datasheets/data/ir2104.pdf May I ask why there are two capacitors instead of ...
2
votes
3answers
7k views

How do I drive a MOSFET working under high voltage while keeping it insulated from the rest of the circuit?

I want to drive a MOSFET with a 50Hz, 50% duty cycle clock pulse. The voltage to be switched is as high as 300V DC. The section inside the dashed lines will stay electrically isolated from the rest of ...
2
votes
1answer
377 views

E.V. Motor Driver (DC). How to protect parallel MOSFETs and the driver?

Overview: I have an electric quad that I have heavily modified. The motor will need to be replaced every now and then because I am driving a 48 volt motor with a 72 volt supply that can give extremely ...
2
votes
1answer
3k views

PMOS Gate Driver using BJT

I'm (again) looking at high-side load-switching. The load shall be switched on with a controlled rise-time (=limited inrush current) and be switched-off quickly when a controller (not shown) detects ...
2
votes
1answer
3k views

High side N-Channel IGBT/Mosfet drive methods

According to this paper http://www.fairchildsemi.com/an/AN/AN-9742.pdf "However, a transformer may cause half bridge crossconduction due to the offset voltage of gatepulse deadtime stage." ...
2
votes
2answers
240 views

LDO to regulate bootstrap voltage

I am designing a BUCK converter 24V/12V, 80A, 300kHz switching freq. It will be used for stepping down battery voltage, so it can be expected for input voltage to vary from 22 to 30 volts. I am ...
2
votes
1answer
149 views

Gate Driver Voltage drifting?

I am using below circuit to differentially drive ultrasonic transducer. It works almost as expected. However, I notice strange phenomenon if i observe the output at the transducer with dual gate ...
2
votes
1answer
4k views

Charge Pump for driving NMOS

I was looking for a way to drive the gate of a power NMOS. Since I've already have a small FPGA available at a independent backup-3V3 rail, I was thinking I could use it's internal oscillator to build ...
2
votes
1answer
351 views

Isolated Gate Driver Consistent Failure

I have a Tesla coil driver, designed around a UCC21520 isolated gate driver. It is operating as a fixed 50% duty cycle half bridge switcher. The frequency is varied from 150kHz to 250kHz. It is ...
2
votes
1answer
140 views

Why does a triac trigger with gate current in either direction?

I've been coming up to speed on thyristors, and triacs in particular. I've found detailed material on them a little hard to find, in particular on the device physics. Horowitz & Hill is silent on ...
2
votes
1answer
839 views

Using cascaded totem-pole structures to supply more current for gate driving

simulate this circuit – Schematic created using CircuitLab I want to drive a totem-pole structure with a logic gate. The problem is, the logic gate can only supply 8.8mA output sink/source ...
2
votes
1answer
1k views

What must be rated maximum voltage of the boot-strap capacitor of a high-side MOSFET driver?

What is the maximum voltage that appears on a boot-strap capacitor? For example, in this circuit, does \$C_B\$ ever charge to a voltage level near \$600V \pm V_{cc}\$ ? Or does it charge to \$V_{cc}\$ ...
2
votes
0answers
51 views

Sizing the input current of a isolated standalone MOSFET gate driver for a stable output

After a suggestion from my previous question I'm planning to use this Photovoltaic isolated MOSFET gate driver to trigger a trigger input of this DAQ. It seems these devices do not require an ...