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Original question:

PMP9484: PMP9484

PMP9484: Design clarification on reference design PMP9484

SREERAG TR
Prodigy 40 points
Part Number: PMP9484
Other Parts Discussed in Thread: TPA3110D2, LM5122

Hi

In the reference design( pdf file name : tidras4 ) there are five 0.009  resistors(R42-R46) kept in between the output of Boost converter (LM5122M) and the class D Power amplifier.(TPA3110D2). But there is no mention of the same in the BOM.Could you please share the specification of the same?

Also what is the purpose of these resistors ? Can we connect the output of the boost converter directly to the Class D power supply input.

In our automotive application we are using 24V battery as the input to boost converter. please suggest any changes required.? We are using TPA3118 class D amplifier instead of TPA3110D2

  • 0
    TI__Guru 68725 points
    Hi Sreerag,

    Thank you for your interests. Let me check with the original designer and get back to you soon.

    Best Regards,
    Youhao Xi, Applications Engineering
  • 0 in reply to Youhao Xi
    TI__Guru 68725 points
    Hi Sreerag,

    I got the answer from the designer: These were actually 0 Ohm on the final board. The intention was to have direct connection between the VOUT and VSupply on final PCB in real applications, so they are not included as must have in the BOM.

    Hope this clarifies.

    Thanks,
    Youhao
  • 0 in reply to Youhao Xi
    Prodigy 40 points

    Thank you Youhao,

    So its not needed in the final design right? In the schematics VOUT and VSupply can be directly shorted ?

    Also can we supply 24V DC at the input of this LM5122 switcher IC? As the input range as per data datasheet is 4.5 to 65 V. We are planning to use the same design in our automotive application in which the vehicle is having 24V battery. Could you please confirm?

  • 0 in reply to SREERAG TR
    TI__Guru 68725 points
    Hi Sereeraj,

    Yes, those resistors are not needed for final product, and VOUT and VSupply should be directly shorted.

    I think you can use 24V for the input. The only thing needs to pay attention is the voltage rating of the components tied to the input line. I checked the BOM and they all >24V. So it is safe to use 24V.

    Please double check to make sure I haven't miss any.

    Thanks,
    Youhao
  • 0 in reply to Youhao Xi
    Prodigy 40 points

    Thank you Youhao.

    I will double confirm the same. This resolved my issue.