LM74910-Q1: How to let MCU control EN if MCU use the output power after two mosfet?

Jass Jin

Part Number: LM74910-Q1

Tool/software:

Hi expert,

My customer want to achieve ASIL-B level for overcurrent and overvoltage protection using MCU ADC channel. However they also want that MCU can be protected by LM74910, so MCU use the power from VOUT.

They use two VBATT/cable and the same VOUT for redundance to realize system ASIL-D.

If EN is pull-up to pin C(6-36V) by default, how to control EN pin by MCU if MCU need to turn off one of the LM74910 for some protection?

7 months ago

0 Shiven Dhir 7 months ago

TI__Mastermind 46170 points

Hi Jass,

If EN has to be controlled by MCU, MCU needs to be active and cannot be placed after Q2.

Regards,

Shiven Dhir

0 Jass Jin 7 months ago in reply to Shiven Dhir

TI__Intellectual 2465 points

Hi Shiven,

My customer has two paralleled LM74910-Q1, MCU will only shut down one of the LM74910, is that OK to put MCU after Q2.

0 Jass Jin 7 months ago in reply to Jass Jin

TI__Intellectual 2465 points

Hi Shiven,

The default setting for EN is pull up to pin C, I think MCU can use an NPN transistor to pull low the EN pin and shut down one of the LM74910 because the other LM74910 is still working. There won't be a case that need turn-off both LM74910. Is that OK?

My customer needs to realize ASIL-B at least using LM74910-Q1, if this not work, may consider change solution.

Do you have any recommendation? Thanks!

+1 Shiven Dhir 7 months ago in reply to Jass Jin

TI__Mastermind 46170 points

Hi Jass,

Yes, if output is always powered, MCU can be placed after Q2.

Regards,

Shiven Dhir

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LM74910-Q1: How to let MCU control EN if MCU use the output power after two mosfet?