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| How to match Mosfet Gate Driver with Mosfet |
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| jmelson:
--- Quote from: ZeroResistance on August 28, 2018, 06:49:40 pm ---OK so maybe I worded it wrongly, however I checked the datasheet and saw that the rise time of the IRF540N is around 35nS @ 50V /16A with a gate resistor of 5 ohm. BTW I do f ind a CL = 1000pF mentioned in the IR2111 datasheet. --- End quote --- Giving a rise time without specifying the gate driver is just meaningless! I seriously doubt you will get any 35 ns risetime with a 200 mA gate driver. I was getting 400+ ns risetimes with a similar triple half-bridge driver all in one package. I then changed to using 3 separate driver chips with a 2A spec, and cut the risetimes to 100 ns or so. Jon |
| ZeroResistance:
So, let's say I use a typical logic level Mosfet, and I don't use a driver and directly drive it from a pin of a microcontroller(Arduino) say with 5V logic and the pin can source a max current of 25mA. How much time can I realistically expect for the mosfet to turn on in? Second point, if the mosfet is connected to a high drain voltage lets say above 80V, will switching drain inductive loads, need any extra circuitry to protect the logic level gate drive? |
| T3sl4co1l:
Switching an inductive load without protection, will require much more robust drive circuitry, to account for when the transistor fails in a three-way short, dumping some fraction of Vds into the gate terminal. You'll most likely just put a TVS diode from ground to drain, to deal with that. Tim |
| ZeroResistance:
--- Quote from: T3sl4co1l on September 01, 2018, 06:55:48 pm ---Switching an inductive load without protection, will require much more robust drive circuitry, to account for when the transistor fails in a three-way short, dumping some fraction of Vds into the gate terminal. You'll most likely just put a TVS diode from ground to drain, to deal with that. Tim --- End quote --- Okay! Thanks for your valuable inputs. Having said that are there mosfet packages available with built in driver? preferably say a Mosfet Half bridge with high side + low side driver. Or even a mosfet full bridge with integrated gate drivers. I have seen lots of motor drivers with mosfet h bridges however they seem to have extra pins for current sensing etc. I am just looking for a plain old H bridge with integrated drivers. |
| blundar:
There are a plethora of such parts on the market. It's going to boil down to how much current you need to switch. Some of my favorite half bridges: ST VNH5019AH Infineon BTN8962A BTN8982A Some of my favorite full(ish) bridges: ST VNH7013AH Infineon IFX007 All of these parts are designed to drive a decent amount of current with an inductive load more or less direct from a MCU. They feature drivers, protection circuitry, integrated FETs and sometimes current sensing and/or diagnostics. They're designed to be an "easy" button for designers compared to using a gate driver, discrete FETs and thinking. |
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