Power rails

board "02-power-rails"

# 12 V bench input to a catalog 5 V regulator.
part U1 = catalog C310413 as "L7805"
# ST DS0422 section 6.1 recommends at least 0.33uF at a remote supply input.
# Use 1uF nominal here; qualify effective capacitance and input-loop placement.
part C1 = cap 1uF 50V
part C2 = cap 1uF 50V
# The flat output model does not enforce the L7805's 5 mA minimum load.
# This sourced bleeder supplies it throughout the required output window.
part R1 = res 470R as "minimum load" lcsc C844786
part GND = ground as "GND" lcsc C0
part J1  = pin_header rows 1 positions 3 pitch 2.54mm labels "VIN" "GND" "OUT" as "breakout"

net VIN { U1.INPUT, C1.1, J1.1 }
net GND { U1.GND, C1.2, C2.2, R1.2, GND.P, J1.2 }
net VOUT { U1.OUTPUT, C2.1, R1.1, J1.3 }

# Authored contact-current ceilings: OUT feeds the external load; VIN and GND
# also carry the bleeder and the regulator's ground current behind it.
interface J1 contacts "OUT" each current max 50mA
interface J1 contacts "VIN" "GND" each current max 75mA

rail "VIN" 12V
power J1.VIN from "VIN"

# Check the regulator's output; a second rail would impose a source instead.
require voltage U1.OUTPUT within 4.75V..5.25V

# State the installation environment for voltage-dependent clearance.
spacing external uncoated

# Rated to 65 C: with the full 50 mA output load the regulator drops about
# 7 V into the 1s0p fixture below, and at 70 C its junction bound passes 125 C.
ambient 0C..65C

# Construction premise requiring qualification. The L7805 thetaJA row lacks
# a named fixture; layer count alone establishes no thermal equivalence.
thermal fixture jedec 1s0p

outline fit
text "L7805 5V Reg" 1.0mm at center 0mm 4mm

emit vocab 1 producer 2 -> "02-power-rails.json"

layout
# Route supply nets at the declared width, then finish other connections.
netclass power nets { VIN, VOUT } width 0.5mm
route netclass power
route remaining
finish connectivity
finish drc

Source saved with this render · 17 Oct 2026