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LM43603: decrease slew rate with resistor in Serie with Cboot

Jon Bilbao
Intellectual 1425 points
Part Number: LM43603

Hi,

Is it true that you can decrease the output slew rate by adding a resistor in serie with Cboot? 

Slew rate of customer is too high, and they want to decrease because of EMI.

If yes, what are the disadvantages of this?

is there a problem of adding 10-20 Ohm in serie with Cboot?

If you have any documentation about this please let me know.

Regards,

Jon

  • 0
    TI__Guru**** 191445 points
    I cannot comment specifically on LM43603, but a series resistor with the BOOT capacitor will slow down the rising edge of the SW node to some degree. When I design with a BOOT resistor using other devices, I usually use a value between 4.87 and around 24.9 ohm. 10 ohm is probably a good starting point. Some devices are very sensitive to having a BOOT resistor with regard to BOOT charging and BOOT UVLO detection. Also Efficiency is worse due to increased switching losses and the small loss in the BOOT resistor itself.