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LM5157-Q1: LM5157-Q1 Boost Configuration in Inverting Mode

Meghla Maji
Prodigy 70 points
Part Number: LM5157-Q1
Other Parts Discussed in Thread: LM5157

Tool/software:

Hi, 

We want to use LM5157QRTERQ1 in our application where we need to convert 12V in Voltage to -13.5V output voltage with 2A current. 

Could you please tell if this is a right choice for this application ?

secondly can you please share spice model for this IC for simulation of 12V - -13.5V generation?

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Thanks & Regards,

Meghla

  • 0
    Prodigy 70 points

    Additionally I would want to confirm if availavle PSPICE model can be used to generate negative voltage ? 

    Also can this be use in LTSPICE?

  • 0 in reply to Meghla Maji
    TI__Genius 15765 points

    Hi Meghla,

    You can useLM5157 in Flyback configuration for example to achieve a negative output voltage. Or you can use it in CUK configuration.

    In the product folder on ti.com you can find the PSPICE model. This model is encrypted, so you cannot import it to LTspice.

    But you can use PSPICE for TI, which is available for free.

    Best regards

    Moritz

  • 0 in reply to Moritz
    Prodigy 70 points

    Hi Mortiz,

    Thank you for your previous response.

    We are using the LM5157 in a boost configuration to generate -13.5V from a 12V input. I have attached a snapshot of the schematic we designed for this purpose. Could you please review the design and confirm if it would work effectively in our application?

    Additionally, we are exploring simulation options in PSPICE for TI. According to TI’s application note, “Application Note - Working With Inverting Buck-Boost Converters,” most regulators’ PSPICE models are not compatible with inverting buck-boost (IBB) configurations due to internal global ground connections, which limit their use in generating negative outputs. Could you confirm if the LM5157 model available on the TI website can be used for negative voltage generation in PSPICE? If not, would you be able to share an alternative PSPICE model of the LM5157 specifically designed for an IBB application?

    Thank you very much for your assistance. We look forward to your guidance.

    Best regards,

    Meghla

  • 0 in reply to Meghla Maji
    TI__Genius 15765 points

    Hi Meghla,

    I recommend to use a buck converter for implementing the inverting topology.

    Please have a look at this reference:

    https://www.ti.com/tool/PMP31291

    Please start a new thred for help with a buck device.

    Best regards

    Moritz

  • 0 in reply to Moritz
    Prodigy 70 points

    Hi Mortiz,

    Thankyou for your previous response.

    Could you please share the PSPICE model of the recommended  buck converter LM70880RRXRQ1 for inverting topology.

    In Webench power designer, how can we draft the schematic for 12V input to -13.5V output using LM70880RRXRQ1.Or can you share any sheets for calculating the values of the components 

  • 0 in reply to Meghla Maji
    TI__Genius 15765 points

    Hi Meghla,

    Please start a new thread and refer to the LM70880RRXRQ1 in the title.

    Best regards

    Moritz