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LM3488: LM3488 as boost convertor for optimum performance

Anand M Tripathi
Prodigy 10 points
Part Number: LM3488

Hi team,

I was designing a boost convertor using IC LM3488 for :

Vin=12V

Vout=100V

Iout=30mA

Voutripple=10V 

Kindly comment whether the selection of the discreetes in my application circuit as in Input capacitor, Output capacitor , Inductor is correct or not.

Due to limitation I cannot go ahead with electrolytic capacitors and in this design I have used MLCC(Multi layer Ceramic capacitor) for input and output.

The 22uF capacitor used in circuit has voltage rating of 100V so two are kept in series.

Kindly confirm whether the following circuit will give optimum performance and reduced noise.

/cfs-file/__key/communityserver-discussions-components-files/196/SCHEMATIC1-_5F00_-5_5F00_RF_5F00_Power_5F00_Supply.pdfThanks in advance.

  • 0
    TI__Guru 58641 points

    Hi Anand,

    thank you for using the E2E forum.

    For the component selection please follow the guidance in the datasheet section 8.2

    With a boost factor of > 8 this is very sensitive and you should carefully check the max duty cycle and also the Diode (esp. reverse recovery Qrr).

    For the capacitors using MLCC is OK but consider the DC Bias for selecting the amount of Capacitors you need.

    Also check the saturation current of the inductor - this can reach up to 540mA - so with some margin a saturation current of 700mA would be good.

    Not sure how you have selected the compensation network but please check this as well - see : https://www.ti.com/lit/pdf/snva067

    Best regards,

     Stefan

  • 0 in reply to Stefan Schauer
    Prodigy 10 points

    Thanks Stefan for the guidance kindly comment whether the Cout vales are ok not . I have put 4 parallel channels where each channel has two 22uF (100V) in series. Can we go ahead with the same or a higher value of Cap is reccomended.

  • 0 in reply to Anand M Tripathi
    TI__Guru 58641 points

    Hi Anand,

    you can stack the Caps but need to consider a high margin due to the tolerances of the Caps.

    With 2 times 100V and an output voltage of 100V this should be OK.

    Best regards,

     Stefan