kushal nandanwar
Full Member level 3
I am using IRFB4110PbF MOSFET , how can I calculate current required by MOSFET gate at 5kHz frequency.
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find Qg parameter in fet datasheet
current needed for gate drive is f(sw) * Qg
ensure your gate drive voltage is same as the datasheet conditions, otherwise it wont be the right formula that you see above.
Remember that Q=CV, where v is the gate voltage that you are driving up to, and Q is the charge needed to get it there, and c is the capacitance seen by the gate drive, which is a combo of gs cap and dg cap...especially with the miller effect
Hi,
Qg in datasheet is given for testconditions. They will not meet the conditions of your application.
But for a raw estimation of average current it may be OK.
Klaus
that is instantaneous current not average current, the fet needs a zap of current to bring it on quickly
Typically you use bootstrap circuits with capacitors 100nF. .. 1uF. They have the same job, with the same gate currents...Obviously I am the capacitor overkill kind of guy so I will give each driver a 470uF cap right next to it which will take care of all surges etc.