LM74900Q1EVM: Modifying EVM to push 30A through board

Part Number: LM74900Q1EVM
Other Parts Discussed in Thread: LM74900

Tool/software:

Hi Team,

I'm working with an engineer that would be interested in pushing 30A through the LM74900, but would like to test it first using the EVM. On our EVM, we note that you can only pass 10A max current through the current setup, so I wanted to understand if the 10A Max current is due to the components (MOSFET, Rsense, other passives, PCB traces, etc...), or if this board can be modified to pass 30A of current?

Anything more than 10A would help, so any guidance or feedback here is appreciated.

Thanks,

4 months ago

0 Shiven Dhir 4 months ago

TI__Mastermind 19000 points

Hi JP.

Welcome to E2E!

The current is limited on the EVM because of the construction of the board (traces, Vias etc.) You can push 30A for short duration like ~100ms. You can go for 15A DC also.

I would not recommend going beyond this.

Regards,

Shiven Dhir

0 Russell Haskell 4 months ago

Prodigy 60 points

This EVM

0 Russell Haskell 4 months ago in reply to Russell Haskell

Prodigy 60 points

This EVM has pads for uninstalled Q1, Q2 & R1 which are in parallel with Q3, Q4 & R2. If I install these parts in parallel can I double the current rating (from 10A to 20A)? Could I then go to 30A for short pulses? OR, am I still limited by PWB traces? Not sure why those parts would be designed into the board unless it was to increase the current rating.

0 Shiven Dhir 4 months ago in reply to Russell Haskell

TI__Mastermind 19000 points

Hi Russel,

You are limited by PCB traces to do so. 30A occasional pulses are fine.

15A DC is also fine.

Regards,

Shiven Dhir

0 Russell Haskell 4 months ago in reply to Shiven Dhir

Prodigy 60 points

So, it doesn't buy me anything to add Q1, Q2 & R1 then. I am still limited to the same Max current because of PCB Traces. Simulation shows that with the 10A jumper in place the Overload trip is approximately 12A. If I add R1 in parallel with R2 that trip point increases to 24A. I guess I should do that so I can run this at a steady state 15A, with short pulses above that. I will also use the 1ms overload trip delay setting. Does this sound OK?

0 Shiven Dhir 4 months ago in reply to Russell Haskell

TI__Mastermind 19000 points

Hi Russel,

Yes, you can add R1 in parallel to R2. If a sense resistor is hard to find,

You can change resistor R20 or R19 to set a higher threshold.

And change R3 to set higher SCP threshold.

Regards,

Shiven Dhir

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LM74900Q1EVM: Modifying EVM to push 30A through board