LM74900-Q1: review the design calculator tool for ISO7637 pulse 5a/5b test

Henry Wang3

Part Number: LM74900-Q1
Other Parts Discussed in Thread: LM74900, LM74930-Q1

Tool/software:

Hi Sir,

My customer would like to use LM74900-Q1 to meet the load dump test(ISO7637 pulse 5a/5b test) and needs the reverse current function, could you please help to review their design calculator tool and advise some comments?

If the LM74900-Q1 could not meet the ISO7637 pulse 5a/5b test, please also advise the correct device. Thanks!

LM74900-Q1_ID_Design_Calculator_20250214.xlsx

7 months ago

0 Shiven Dhir 7 months ago

TI__Mastermind 48475 points

Hi Henry,

LM74930-Q1 will be a better pick to meet pulse5A.

Please consider it once and we can move to reviews.

Regards,

Shiven Dhir

0 Henry Wang3 7 months ago in reply to Shiven Dhir

Genius 3355 points

Hi Sir,

Could you please advise some comments after reviewing the below schematics and the design calculator tool again? Thanks!

May I remove those 0 Ohm resistances (R1749, R1750, R1753, R1755, R1756, R1757)?

LM74900QRGERQ1_schematics.pdf

LM749X0_ID_Design_Calculator_0217.xlsx

0 Shiven Dhir 7 months ago in reply to Henry Wang3

TI__Mastermind 48475 points

Hi Henry,

Please leave the pin25 floating otherwise reverse polarity protection will be lost.

Yes, 0ohms resistors can be removed. They are just placeholders for easier rework on board.

Rest, the schematic looks fine.

The design calculator is not filled correctly in section3. Startup SOA may not have much margin when load is turned on during startup.

Regards,

Shiven Dhir

Power management

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LM74900-Q1: review the design calculator tool for ISO7637 pulse 5a/5b test