Re: Balance resistor circuit for paralled linear mosfets?
shapirus on 01 Jun, 2024 07:32 in Beginners
Quote from: trilerian on 01 Jun, 2024 03:05If I am following this, that would be for a P channel mosfet? If I am using N channel, would the resistor go between the drain and gnd? And if so, that raises more questions. Nope. N-channel mosfets (when used as switches or, like your case, current controlling elements) are normally connected between load and ground: source to ground, drain to load, gate is the controlling pin. Controlling voltage is applied between gate and source, which is "by default" the same as ground.If you add a resistor between source and ground and still apply your controlling voltage between gate and ground, then the actual controlling voltage, Vgs aka gate-source voltage, that the transistor sees, will be a difference of the gate-ground voltage and the voltage drop across the resistor (the higher the current, the higher the voltage drop).To sense and control current, a current sense resistor (typically very small, like mΩ-small) is added typically between source and ground. It is selected to be small enough for the planned load current so as not to have a significant effect on Vgs. A balance resistor, on the other hand, should be large enough to affect Vgs when necessary.It's the reverse with P-channel mosfets. Their source connects (typically) to the positive power rail and drain goes to load (the other terminal of the load goes to ground).More details on this (basic) topic can easily be found on the internet, e.g. https://www.electronics-tutorials.ws/transistor/tran_7.htmlAt the same time, you said that you built a 80A current sink successfully, so now it's my turn to be confused, meaning... it's time to show your circuit!