Placement Review

Owned by Farris Matar
Sept 01, 2022
3 min read

5V Buck Converter:

  • Move these components closer to the IC. Additionally, move the bulk capacitor (C301) to be next to the IC, to the right of R302/R303, as it will help maintain the input voltage better when it’s closer

  • Move C305 up above the IC so that it’s closer to the BOOST pin. Additionally, bring C306 down to be next to the VCC pin. Decoupling caps work best when they’re as close as possible to the pins they’re decoupling

  • Move the feedback resistors (R305 and R307) up above the inductor, next to C310. The VFB line is a very sensitive signal and so it needs to be further away from the inductor

  • Fix the buck IC footprint so EPAD is numbered 17 instead

  • Otherwise, placement is excellent, nice work

17V Buck Converter:

  • Same comments as above for the capacitors (C201, C205, C206). Move them to match the comments on the 5V buck and have them close to the IC

  • You can bring these components much closer to the IC, they don’t need to be so far away

  • Swap Q202 and Q201 around. Q201 is the high side MOSFET, so it needs to be above Q202 since the VBAT power input is coming from above

  • Otherwise all looks good

Schematic Comments: Minor changes to the schematic to fix some things up and make layout easier

  • Remove net names on wires that are connected to power ports. This messes up the names of the power rails in the layout, which can make layout confusing. The net names you need to delete are:

    • BURST_EN_17V (pin 4 of the buck IC in BOTH buck converter schematics, currently it renames the GND net)

    • VIN 17V and VIN 5V (currently they rename the VBAT_FUSED net)

    • SENSE- 17V and SENSE- 5V (currently they rename the 17V and 5V nets)

  • In the 17V buck converter schematic, D201 still needs to be updated to match the new symbol

  • I just noticed this now, but R308 in the 5V buck is too small for the amount of current that’ll be going through it. Since 10A will be going through this resistor, let’s swap it with a resistor that’s rated for at least 1W and has a bigger footprint

  • On the Power page, bring the GND port to the bottom of the 2 connectors, it’s good practice to have everything connect to GND at the bottom

  • Add a 1k resistor on the IN line here, it will limit the current that goes to GND when we turn the switch off