I'm working with a bootstrap gate driver circuit in a project right now. It's for an inverter.

Should the PWM signal be coming from the cathode to the anode?

 

Please post a schematic. You can see " cathode to the anode " and we can not see anything.

 

Yes, schematic would be best in order to help you.

 

Are you working with a reference design? And not a full fledged design?

 

I'm working with an HCPL-3120 Opto Driver IC.

HCPL-3120

The HCPL-3120 2.5A gate drive optocoupler will drive IGBTs and MOSFETs. Applications include AC and brushless DC motor drive, switching power supplies and induction cookers.

www.broadcom.com

Thanks.

 

Michael Mayorkas
It is hard to know what your question is. This schematic is in the data sheet for the 3120. What " cathode to the anode " ?

 

It is generally recommended to drive the gate of a MOSFET with a PWM signal from the anode to the cathode, as this will reduce the conduction time of the MOSFET and minimize power loss. This is known as "forward conduction" and is the normal operating mode for MOSFETs in inverters.

However, it is also possible to drive the gate of a MOSFET with a PWM signal from the cathode to the anode, which is known as "reverse conduction" or "drain-source reversal." This can be useful in certain applications, such as when driving a motor in both forward and reverse directions. However, it is generally not recommended for use in inverters, as it can result in increased power loss and reduced efficiency.

It is important to note that the polarity of the PWM signal should be carefully considered when designing a bootstrap gate driver circuit, as the polarity of the signal will determine the direction of current flow through the MOSFET and will affect the performance of the circuit.