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LMR36015-Q1: Inductor Inquiry

Part Number: LMR36015-Q1

Hi, 

Good day. I hope you are doing fine. 

Our customer wants to use the LMR36015-Q1 in their ECU and he has a question regarding the inductor value for his design. They intend to use this to step down the 24V to 12V/1.5A, 400kHz. On the datasheet, table 3,  they noticed that the suggested inductor is 27uH however they want to know if they can use a 22uH or 33uH inductor for this application as this is readily available on their inventory. Furthermore, they want to know the risk/effect of using the 22uH or 33uH inductor on their circuit. If this is possible, which one would be better in their target application. 

Looking forward to your response. Stay safe and have a great day. 


Regards, 

Cedrick

  • Hello,

    For greater than 50% duty, worry is for subharmonic oscillation. This presents lower bound.

    Lower bound can be determined by equation 5 in d/s.

    Controller needs to see some slope on the inductor current for proper regulation.As a rule-of-thumb, the minimum inductor ripple current must be no less than about 10% of the device maximum rated current under nominal conditions.

    That would be the upper bound, but often cost and size of inductor trumps this calculated upper bound.