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LM3478: Non isolated Boost 24V to 180V

vemana shankar
Prodigy 30 points
Part Number: LM3478
Other Parts Discussed in Thread: LM5155

Hi,

I need to validate the below power supply design for our product 

Input voltage: 24V

Output voltage 180V

Topology: Boost non isolated

Ripple less than 50mV 

Output current: 200mA

Have Selected LM3478 and its associated parts mentioned below

PCB size within area of 70mm x 50mm

 

MOSFET: IPT60R125G7XTMA1

Diode: C3D02060E  

Inductor: 300uH (yet to select the part from wurth) with Sat current 1Amp

Output capacitor: B58035U5305M062 (3uF)  

Input capacitor : 10uF

 Regards

Vemana Shankar

  • 0
    TI__Mastermind 30895 points

    Hi Vemana,

    Thanks for using the LM3478. What is your switching frequency? Your selection of components will depend on that as well.

    Additionally, if you are not aware of it- the LM3478 has a next-gen variant called the LM5155, and I've attached a reference design using the Webench design tool.

    Thanks,

    Richard

  • 0 in reply to Richard Fu22
    Prodigy 30 points

    Hi Richard,

    Thank you for your immediate response 

    Can we use the same reference design for generating 300V @ 200mA output by just changing the feedback resistors.

    Next the reference design ripple is 300mV and our requirement for the product needs less than 50mV ripple. 

    The ripple voltage is higher is it because of the Cout of less value 1.3uF and 10nF. Need your advice on this.

    Regards

    Vemana Shankar

     

  • 0 in reply to Richard Fu22
    Prodigy 30 points

    Hi Richard,

    Actually our requirement is two different voltage sources of Vout1 is 300V at 200mA load and Vout2 is 180V at 200mA load. 

    with same input voltage 24V, can you send us two different webench reference designs. its used for the mass spectrometer voltages. 

    Regards

    Vemana Shankar 

  • 0 in reply to vemana shankar
    TI__Mastermind 30895 points

    Hi Vemana,

    You can access the Webench design here: https://www.ti.com/product/LM5155

    Unfortunately, I'm unable to completely provide the second reference design due to limitation with Webench tool and part limitation. You appear to have hit maximum duty cycle on the part for 300V output. What you could do instead is generate a 150V boost design, and then apply a doubler circuit at the output as shown here (please note this design has multiple stages of the doubler circuit). 

    If you wish to generate other voltage rails, you can take the above reference design, and modify the power-stage/compensation accordingly to generate your desired output. There is a boost quick-start calculator on the page attached here.

    Thanks,

    Richard