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can boost converters cause gate loop ringing

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Zak28

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MOSFETs can be very inefficient with insufficient Vgs even if peak current is coming from a capable gate driver but at insufficient voltage.

Would a high frequency switcher such as this MT3608 cause gate loop ringing or other issues for supplying a gate driver which would output ~5amps peak and ~40mA RMS?
View attachment MT3608.pdf

An electrolytic or larger MLCC can be added to the gate driver supply rail across the recommended 22uF MLCC filter to handle peak currents.
 
Last edited:

Hi,

A gate driver delivering too low voltage is simply "unsuitable" independent of it's current capabilities.
Choose another, suitable driver.

As the MT3608 is non isolating, you can just use it for a low side MOSFET.
The use of it makes no sense in my eyes.
It's input is DC, it's output us DC and both are connected via GND...thus (the DCDC part) it should not be included in the gate loop.
(Only the output capacitor)

RMS is not useful here, better use "average" ... and average current should be rather low. It should be equal to
Q_gate_tot x frequency.

I assume any electrolytics - with it's high ESR - is not suitable to support the 22uF MLCC.
Any additional MLCC will not bring much benefit ... because of the low Q that is drawn by every switch ON.

Klaus
 

To discuss "gate loop" ringing, we should look at the gate driver circuit, not a boost converter data sheet.
 

Hi,

A gate driver delivering too low voltage is simply "unsuitable" independent of it's current capabilities.
Choose another, suitable driver.

As the MT3608 is non isolating, you can just use it for a low side MOSFET.
The use of it makes no sense in my eyes.
It's input is DC, it's output us DC and both are connected via GND...thus (the DCDC part) it should not be included in the gate loop.
(Only the output capacitor)

RMS is not useful here, better use "average" ... and average current should be rather low. It should be equal to
Q_gate_tot x frequency.

I assume any electrolytics - with it's high ESR - is not suitable to support the 22uF MLCC.
Any additional MLCC will not bring much benefit ... because of the low Q that is drawn by every switch ON.

Klaus

I meant the mt3608 for lowside switching and didn't include that in the original description.

It should serve fine for supplying low side NMOS gate driver?
 

I meant the mt3608 for lowside switching and didn't include that in the original description.

It should serve fine for supplying low side NMOS gate driver?

PIN #1 (SW) of the MT3608 is a Low Active MOSFET only, it does not source any current - it is not a Gate Driver - it is the "PWM switch".
I assume you are trying to add an external MOSFET?
Please, post a schematic.

And then clearly explain ...
How you are going to use the MT3608 to Source current into & Sink current from the Gate of the external MOSFET, without adding a GATE DRIVER?
 

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