Which of the two following PCB layouts for the given schematics (7805 voltage regulator) is better? Do filled zones affect filter/decoupling capacitors negatively?


Update: Second layer is a ground plane.



Variant 1 (Filled Zones)

Variant 1

Variant 2 (Traces)

Variant 2

  • 2
    \$\begingroup\$ That schematic and this questions tell me you take decoupling serious. So, don't use an ancient voltage regulator. Modern voltage regulators have better regulation, and hence achieve cleaner / stabler output voltage with less capacitors. The heatsink, and the 12 V input voltage tells me that for the price of your capacitors, you could realistically have built a switch-mode step-down supply, to, say, 6V, and followed that with a lower-voltage drop linear regulator that's lower noise than the LM7805, thereby saving your the thermal problems you'll have. \$\endgroup\$ Feb 22, 2021 at 16:31
  • \$\begingroup\$ Regarding the traces: unless your 12 V is really really unreliable, your capacitors are overkill and slightly thicker traces would work exactly as well as a plane, no clear preference. \$\endgroup\$ Feb 22, 2021 at 16:31
  • \$\begingroup\$ I don't see how these are equivalent, how in the "zones" one are you handling grounds? Are we only looking at the power rails and you are handling ground as a continuous plane on the bottom? \$\endgroup\$
    – Ron Beyer
    Feb 22, 2021 at 16:32
  • 3
    \$\begingroup\$ To be honest, I think this decoupling/bulk capacitance is a bit overkill. One bulk capacitor (maybe 10-100uF depending on the application) and two local capacitors on the input (0.33uF) and output (0.1uF) of the regulator should be perfectly adequate for the current handling capabilities of a basic linear reg. \$\endgroup\$
    – DerStrom8
    Feb 22, 2021 at 16:38
  • \$\begingroup\$ Yeah. That's overkill. You can find 200A motor drivers with 1/4 that capacitance. \$\endgroup\$
    – DKNguyen
    Feb 22, 2021 at 17:02


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