0
\$\begingroup\$

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

Thanks!

Update: Second layer is a ground plane.

Schematics

Schematics

Variant 1 (Filled Zones)

Variant 1

Variant 2 (Traces)

Variant 2

\$\endgroup\$
10
  • 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\$
    – Marcus Müller
    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\$
    – Marcus Müller
    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

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.