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MPS MP4008 PCB design

Discussion in 'PCB Layout, Design and Manufacture' started by CommanderLake, Jun 3, 2019.

  1. CommanderLake

    CommanderLake

    189
    5
    Oct 2, 2012
    I've been designing a PCB for an MP4008 driven LED controller to power a CMA3090-0000-000Q0U0A40G from a car (approximately 13.5-14.5v) to 3.6A at up to 50V and was wondering if there are any experts here who could take a look at my design and point out any possible issues.

    I use DipTrace, the .dip file is in the attached zip.
    The large white rectangle represents the heatsink to which it will be mounted.
    The PCB will be mounted to the surface of the heatsink with 8mm standoffs with the GaNFETs underneath the PCB bolted to the heatsink.

    For dimming, rather than use the suggested PWM dimming circuit that seems inefficient, I'm doing this to adjust the current:
    An OPA197 and pot-resistor 10-1 adjustable amplifier for the feedback signal, MPS said doing this would be fine.
    A trimpot-resistor in parallel to the dimming pot-resistor to set a current limit.
    I have verified the low voltage single rail capability of the OPA197 to single digit mV and it performs very well.
    I have a 3-1 resistor divider to hold the PWM pin high.
    Here is a simulation to visualise how the OPA197 feedback amplifier will work using the Falstad circuit simulator: http://tinyurl.com/yybrjtb7

    For the 4 parallel switchers I'm using Transphorm TPH3206PSB GaNFETs
    For the diode I'm using an Infineon IDH20G65C6-DS SiC Schottky diode
    The input capacitors will be 4x 100μF 25v Wurth Electronics Inc. 870025574005
    For the output capacitor I have a 100μF 100V polyester AVX FFV34E0107K--
    The inductor will be a 10μH Wurth Electronics Inc. 7443641000
    U3 is an LM2940CT-12

    I am aware the GaNFETs should have 20-25Ω to the gate but the output of the MP4008 is limited such that extra resistance is likely not needed.

    Here is a link to a spreadsheet supplied by MPS for calculating the components for the MP4008 and similar devices filled with the values applicable to this application, see the "Basic Parameters" page: https://docs.google.com/spreadsheets/d/1VloYdCfMmE4kSOvmKdVUgzby0N3N9jzjAQ_L-XlGQok/edit?usp=sharing

    It doesn't have to be practical as its only a one off for me to use.
     

    Attached Files:

  2. CommanderLake

    CommanderLake

    189
    5
    Oct 2, 2012
    Thread obsolete.
     
  3. davenn

    davenn Moderator

    13,342
    1,773
    Sep 5, 2009
    why ?

    if you have updates, then add them for people to learn :)
     
  4. CommanderLake

    CommanderLake

    189
    5
    Oct 2, 2012
    davenn likes this.
  5. CommanderLake

    CommanderLake

    189
    5
    Oct 2, 2012
    Given up on the AL3353 because I cant figure out what should be on the COMP pin and it requires bigger shunts decreasing efficiency.
    I reduced the size a lot by replacing the output capacitor with a couple of 100uF ceramics and using the main heatsink for the diode next to the MOSFET with insulating thermal pads and washers.

    I like the specs on this MOSFET: ON Semiconductor FDP150N10A-F102
    I've had this heatsink for a long time so I'll use it for now: ABL 350AB1500B
    The input caps are now 2x Panasonic 20SEPF560M, I already have them.
    I also have the diode: Infineon IDH20G65C6XKSA1
    This is my digikey basket: www.digikey.co.uk/short/pbf3vb
    You can get the .dip from my server: http://commanderlake.net/MP4008.dip
    DipTrace Free: https://diptrace.com/download/download-diptrace/

    The green represents the heatsink
    PCB_front.png
    PCB_rear.png
     
  6. CommanderLake

    CommanderLake

    189
    5
    Oct 2, 2012
    Are there no PCB design experts here?
     
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