# Tag Info

## New answers tagged gate-driving

4

Some FET circuits, with various parasitic capacitances (including inside the FET) and inductances (including the FET packaging) and lumped loads, WILL OSCILLATE. Having gate resistances (as an option) provides a means to dampen the circulating energy, if the C_gate_drain or C_gate_source is in the resonant loop.

2

No, you do NOT requires a pulldown resistor for the gates. This is already built into the driver and the driver when powered on will immediately have a defined state. You MAY require a series resistor since the the driver is rated for only 1.5A maximum. The series resistor is used to limit maximum current and reduce parasitic ringing which may increase ...

1

A resistor in series between the MOSFET gate and driver give you the chance to adjust the speed of your MOSFET switching. A pull down at the gate of the MOSFET, may or may not needed. You can refer to here.

8

Maybe. The MC34152 datasheet pp.8 on shows a series Rg to damp oscillations, and reverse-bias Schottky diodes for catching negative ringing spikes at the driver. Wouldn't hurt to have these in your layout. You could stuff zero-ohm for Rg if you don't need damping, and no-stuff the diodes if you find the ringing isn't too bad. Have one resistor/diode per FET, ...

4

You might not need a gate resistor but if this is a custom PCB, you should make space for one and just jumper it if it is not needed. Gate resistors slow down the rise time which can result in EMI, ringing, and damaging spikes. Ferrite beads can also be used instead of resistors. You want one resistor per gate and you want the resistor close to the gate. ...

1

If you never wanted the load current to go to zero this would be a good way to do it, a little odd because generally mosfets should be in the on or off state, not in between as they dissipate a lot of power. A circuit like this might be useful for a hit and hold on solenoid or something like that. If you want to use this circuit, make sure you check the ...

1

In a switching converter this is desirable because it means that it lets the current in the inductor never fall to zero which lets you run in continuous mode instead of discontinuous mode which produces less ripple and noise (I think...it's something like that). In a motor this is desirable because you don't throw away all the energy put into building up ...

1

You typically choose a PWM frequency high enough to limit the ripple in the current through the motor to prevent torque oscillation and audible noise, and so the current during the off period won't decay to zero except at very low duty cycles. At 50% duty cycle, the motor will be running at about half full speed, and the current through the freewheeling ...

0

How can I find Gate charge of the mentioned mosfet gate driver? You won't. The gate charge is a characteristic of the device you are driving. To turn it on you must transfer that charge to the gate, to turn it off you must remove that charge. How fast you want to do this (your switching frequency) will determine the current that will flow. The peak current ...

1

(96V - 12V) across 470 ohms is 180mA through your zeners. That is 12V * 180mA = 2.16W dissipated in the zeners. I don't know what zeners you have but that's probably near the zener's limit so you probably do want to increase the resistors. Your resistors are also dissipating power so they also will heat up more unless you increase resistance. About Four ...

1

To properly measure the fall time of Vout you need to connect something to that point that will pull the voltage down...the PMOS transistor can only pull Vout high. With just an oscilloscope probe connected to Vout the fall time will be very slow, because the oscilloscope probe is intentionally designed not to alter the circuit voltage. If you just want to ...

1

Companies that make MOSFET devices often publish useful papers called application notes (or white papers, or bench notes, etc.) to help engineers better understand these devices. Listed below are three examples. I also recommend an Internet search using keywords like "MOSFET switch capacitive load". Texas Instruments Application Report SLVA883 Timing of ...

2

With this arrangement D4 clamps negative Vgs and the other diodes provides a load impedance above Vgs(th) if less than 1.8V , then you can drive it with a current source with pull up or a voltage source or even a capacitor with diode negative clamping with PWM if you thought this was an advantage for isolated DC driving of the gate at some different ground ...

3

In such cases, it is useful to redraw the circuit: as @Oldfart says in their comment, we have the following situation simulate this circuit – Schematic created using CircuitLab The source of the power MOSFET is connected to the ground via three of the four diodes $D_1, D_2, D_3, D_4$ packaged as a couple of double diodes: the resistors $R_{21}$ ...

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