UCC27524A: Output pulse current capability and top metal pad function

Hi Zhenyu,

Thanks for your interest in our driver, my name is Mamadou Diallo from the High Power Drivers group, I will help address your questions.

1. The 5A/0.5us abs max specification means that the max source capability of the driver is 5A and the driver can only sustain that much
peak sourcing current for 0.5us. From a sink current perspective however, you may want to be careful, we do not recommend operating the device outside of the recommended operating conditions specified in datasheet. The driver might not be able to sink 6A of current even for a very short duration. DO you really need that much source/sink current capability? What application is this for?

2. Yes, a heatsink-PCB ground connection is feasible if necessary. I am not sure what the switching frequency and load are but if you may not need heatsinks.

Regards,

-Mamadou

Hi Mamadou,

This is industry application which has high requirement on power efficiency. It is desired to turn off MOSFET as fast as possible to increase power efficiency. Thus the gate driver sink current can exceed 5A for tens of nano seconds in estimated worst case. Can you explain how the 5A/0.5us criterion is decided? What are the limiting factors? I can then decide how to proceed. 

Is the top pad as effective as the bottom pad regarding heat dissipation? 

Thanks,

Zhenyu

Hi Zhenyu,

The drive current of our devices are design parameters therefore attempting to sink 6A of current through the driver may (over time) present reliability issues given that you're stressing the internal pulldown FET Rol highlighted below which may not be able to sustain over time.
From I've seen in most applications with this driver, the bottom pad along with external gate resistance are generally sufficient to adequately help dissipate power away from the driver.

You may also want to consider as an alternative 2 single-channel drivers like UCC27511A more than capable of sinking up to 8A of current and sourcing 4A to the MOSFET more than adequate for your application needs with board space for trade-off.

Please let us know if you have further questions or press the green button if this addressed your questions.

Regards,

-Mamadou

Hi Mamadou,

I see in another post that TI doesn't think 5.9A sink current is a problem: e2e.ti.com/.../584790

I wasn't talking about the bottom pad. I want to know about the exposed metal area on the top of the device. Is the top pad thermally effective for heat dissipation? Is it electrically safe to connect the top pad to GND potential?

Thanks,

Zhenyu