LM5575: output inductor selection

Srinivasu V

Part Number: LM5575

Hello,

Due to non-availability of high (68uH or 47uH) value with high current inductors in our database, we are planning to reduce the inductor value to 33uH by increasing the Ip-p. to 1.2A

As per the calculation, only output capacitor value I have to increase.

My question is:

is there any impact on the efficiency or any other functions?

I have consider below.

Vout : 15V

Output Ripple : 100mV

Iout : 0.6A

Fsw : 260Khz

Kindly clarify.

over 4 years ago

0 Arief Hernadi over 4 years ago

TI__Mastermind 23815 points

Hi,

It looks like the at 75V input your current ripple will be roughly 1.2A peak to peak.

Operation wise, it should be ok. Efficiency will get affected for sure.

Is it an option to put 2x33uH in series?

Thanks

-Arief

0 Srinivasu V over 4 years ago in reply to Arief Hernadi

Intellectual 360 points

Hello Arief

Please find the below our design details.

Vin : 18 to 32V

Vout : 15V

Iout : 0.6A and peak 1.5A short time (1mS)

Fsw : 260Khz

as per calculation, recommended inductor value is more than 68uH. as our customer wanted to 33uH inductor.

is it ok, if we use 2 inductors in series?

Thank you,

Srinivasu

0 Arief Hernadi over 4 years ago in reply to Srinivasu V

TI__Mastermind 23815 points

Hi,

Yes, you can use 2 inductor in series especially if it is the same inductor, therefore it will have the same saturation current.

Thanks

-Arief

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LM5575: output inductor selection