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LM5642X: Design help and clarification

Genius 14959 points
Part Number: LM5642X
Other Parts Discussed in Thread: LM5143, TPS5120, LM5642, LM25117

Hi Experts,

Good day. Asking assistance on this query:

I have a few questions related to part number LM5642x.
After going through the datasheet and I understand that configuring as a single parallel operating, the converter can drive a max load of 20A.

Question:
Can the converter handle to drive a load of for example channel1 with 15A and channel2 with 5A separately?

This is because I want to use this converted where,

supply input is Vin = 24V,
Channel 1 should drive 15V, 10A
and
Channel 2 should drive 5V, 2.5A.

Regards,
Archie A.

  • Hi Archie,

    Asymmetric loads shouldn't be a problem. Our latest dual-ouptut controller is the LM5143 - take a look as it has higher performance. A quickstart file is available to assist with component selection etc.

    Regards,

    Tim

  • Hello Tim,

    Thanks for your response and recommendation.

    With specific given below, the asymmetric load on LM5642x is applicable, correct?
    Vin = 24V

    LM5642x Outputs
    Ch1 out = 5V, 2.5A
    Ch2 out = 20V, 15A
    Of course, with suitable components of high ratings (inductors, FEt's, sense resistors etc).

    However, LM5143 which you have suggested is QFNP type which is not suited to my clients current machine set-up as it is designed for TSSOP or HTSSOP types.

    We would be more than happy if you can suggest a buck controller with dual output that can handle more than 20A load and TSSOP or HTSSOP types it would be great.

    Regards,
    Archie A.

  • Hello Tim,

    Thanks for your response and recommendation.

    With specific given below, the asymmetric load on LM5642x is applicable, correct?
    Vin = 24V

    LM5642x Outputs
    Ch1 out = 5V, 2.5A
    Ch2 out = 20V, 15A
    Of course, with suitable components of high ratings (inductors, FEt's, sense resistors etc).

    However, LM5143 which you have suggested is QFNP type which is not suited to my clients current machine set-up as it is designed for TSSOP or HTSSOP types.

    We would be more than happy if you can suggest a buck controller with dual output that can handle more than 20A load and TSSOP or HTSSOP types it would be great. Also, can this part TPS5120 work as well on this application?

    Regards,
    Archie A.

  • Hi Archie,

    The output current is determined more by the power stage, not really the controller. The load requirements sound fine here. You can use the LM5642 if a  leaded package is required. An alternative would be to use a converter (with integrated FETs) for the 2.5A output and then use a single -output controller for the 15A output, e.g. LM25117.

    Regards,

    Tim