Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [gate-driving]

Interfacing between control signals and power switches, like MOSFETs and IGBTs; charging the gate capacitor of a transistor to the voltage required to make it switch while supplying enough current to make it switch at the required speed.

Recommended reading:

Microchip application note AN786: Driving Power MOSFETs in High-Current, Switch Mode Regulators

TI application note SLUA618: Fundamentals of MOSFET and IGBT Gate Driver Circuits

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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 electronic load circuit that must be able to step…
scanny
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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 free wheeling). What is the criteria behind…
raforanz
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Why have both: BJT and FET transistors on IC output?

This is the structure of FAN3100 gate driver IC: (taken from its datasheet) As you can see - there are two ouput switches: CMOS and BJT. Why they put them both?
Roman Matveev
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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 I don't understand is the high-side driver…
Dan Laks
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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 considered bad, wasting energy and shortening the…
piojo
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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 for M1, and the microcontroller is able to turn it on and…
Phil Frost
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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 compatibility? What are the essential differences…
hkBattousai
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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 can I get the Vout to be more trapezoidal? Or…
hassan789
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How does this PNP transistor improve the switching performance of MOSFET?

My guess is PNP transistor might ensure fast turn off by shunting the gate capacitance (ie, when diode is reverse biased and the PNP is on.) Additional questions: Why is the gate current limiting resistance not present? What is the role of R1 in…
Divya K.S
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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. L is the trace inductance between the MOSFET gate and the output of the MOSFET driver. C is the…
hkBattousai
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Bootstrap circuit function

I have some question about the bootstrap capacitor on a gate driver. First, the bootstrap capacitor is used because the voltage on the high-side driver's gate needs to be about 10-15 V higher than the voltage on its drain. However, if my input…
sean900911
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Using a miniature BNC connector on a PCB to measure high-frequency content with an oscilloscope

I am a power electronics engineer in R&D and often measure fast switching waveforms, specifically high bandwidth MOSFET gate signals. When connecting oscilloscope probes in the past I have found that the ground clip often induces unwanted HF content…
Jono Moran
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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 MOSFET. Now let's look at the structure of the GPIO…
Roh
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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 low side MOSFETS independently. However, my control…
hkBattousai
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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 application circuit from its datasheet: And its…
hkBattousai
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