MCF8316A: Automotive Load Dump (58V)

Hi James,

Thanks for your question on the Motor Drives E2E Forum. 

One thing you might consider is using our new integrated BLDC gate driver IC MCT8329A: https://www.ti.com/product/MCT8329A

This is a 60V part that integrates sensorless trapezoidal control and a gate driver. This will cover the high transients you mentioned when operating at 32V. However, you will need an external power stage as the MCT8329A does not have integrated FETs. 

Can you tell me which features about the MCF8316A you like and which are non-negotiables if I were to recommend a new device?

Best,

Robert

Thanks for the reply.

This is for an automotive application (cost is the driver). The integrated FET's is what makes this part very attractive. Even if we have to add a fancy voltage cut-off circuit it should be cheaper than 6 (or 3 dual) external FET's.

I was hoping that somebody else has tested this device to automotive transients already that could provide feedback. The datasheet mentions nothing other than the 40V absolute max.

Hi James, 

Let me get back to you on this inquiry by the end of next week.

Best,

Robert

James Raymond said:

I was hoping that somebody else has tested this device to automotive transients already that could provide feedback. The datasheet mentions nothing other than the 40V absolute max.

Well, the devices are used in all kind of environment, so I don't expect the datasheet to cover the automotive load dump case. It states the absolute max 40v and so the users must deal with this limit and protect it. Load dump event can be long, so I don't think using TVS to limit the voltage of below 40v is the right choice. You should consider the load dump can last more than a few seconds, not a fraction of second as in ESD events. 

The car alternator load dump is a high current event and long, so TVS might not survive. 

Brian

Agree, load dump is a harsh pulse. In my case its 58V for 600ms, which is the standard requirement for new 24V battery systems. The more I dig in the more I’m thinking a TVS solution is not going to happen. My challenge is going to be adding a protection circuit that doesn’t add more cost than the IC its protecting…. 

Hi James,

Depending on where the cut off point is for the costs that you are trying to save, it may make sense to look at a higher voltage driver with external FETs until we have a suitable replacement for your application. I understand that the power stage may be more expensive than the protection circuit but we do not recommend exceeding 40V on this device, even in the case of a load dump transient spike. 

Here are some other part recommendations that may be suitable for your application.

If you need Q1 rating, DRV8343-Q1 (65V Abs Max) or DRV8300-Q1 (100V Abs Max).

If you do not need Q1 rating then I can recommend DRV8350/3 (100V Abs Max), DRV8300 (100V Abs Max), DRV8328/9 (60V Abs Max), or DRV8320/3 (60V Abs Max).

Best,

Robert

Thanks for the feedback Robert. The driver needs to be standalone and be "code free" so I think the MCT8329A would be my only other option, which is rated for 60V. But it requires external FET's which may cost more than the MCF8316A with an over voltage cutoff circuit. I may need to work on these in parallel until cost can be determined.