LM74502: Paralleling FET's

Supira Medical

Part Number: LM74502

Hi,

What are the considerations for paralleling MOSFET's if high current control is desired? In this case, I would use the common-source B2B configuration. I'm looking to control 100 A in a 12-volt system, with unsuppressed load dump protection. If you have recommendations for specific FET's, that'd be much appreciated.

Thanks!

7 months ago

0 Shiven Dhir 7 months ago

TI__Mastermind 21160 points

Hi Supira,

When paralleling the FETs, the turn on time will increase as you will need to scale up your charge pump cap as well. Since charge pump cap is bigger, it needs time to reach certain threshold (6.6V).

Also, you can add ~5-10ohms gate resistor at each FET gate to dampen oscillation due to parasitic.

Regards,

0 Supira Medical 7 months ago in reply to Shiven Dhir

Prodigy 160 points

Hi Shiven,

Thanks for the response. In my application, the response time won't be an issue. A second question - for a 12 volt system, what should the maximum voltage be as a design constraint? The ISO pulse test suggests the maximum is between 79 and 102 volts. The datasheet for the LM74502 uses 200 volts because of a 24 volt system.

Thanks!

0 Rakesh 7 months ago in reply to Supira Medical

TI__Guru** 103241 points

Hi Supira,

If you need to design 12V system for suppressed load dump then it is only 35V. For unsuppressed 102V case, you need to consider configuration like Figure 9-8 in the data sheet.

Best Regards,

Rakesh

0 Supira Medical 7 months ago in reply to Rakesh

Prodigy 160 points

Thanks!

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LM74502: Paralleling FET's