Quad BLDC Drone ESC Design

flux

Recorded the new constraint: all boards must fit within about 60 mm × 200 mm max.
Updated:
Impact:
  • The 60 mm width is tight but workable if the high-current bus runs lengthwise.
  • I now recommend reserving a 40–50 mm effective copper/busbar corridor for aggregate 6S current and keeping logic/regulator/ADC routing outside that corridor.
G

gunny59

are both the power management PCB and ESC PCB ready to be modelled in your PCB viewer?

flux

I’ll quickly check the schematic/layout readiness state for the ESC and power-management sections, then tell you whether they’re ready for PCB modeling or what must be fixed first.

flux

Not yet. The PCB viewer can show a rough layout now, but the ESC PCB and power-management PCB are not ready for meaningful PCB modeling/layout release.
Main blockers:
  • Current board outline is 160 mm × 100 mm, not your required ≤60 mm × 200 mm.
  • ESC schematic is incomplete: MOSFET power stages, gate-drive support, current sense, bulk capacitance, MCU↔DRV8308 control wiring, reset/boot/debug, and decoupling still need completion.
  • ERC still has many unfinished MCU/DRV8308 floating-pin warnings.
  • PM board is closer, but still has one known ERC issue: U7 NC tied to SW, which is datasheet-guided but tool-flagged.
  • Placement is congested around motor connectors/drivers and needs a deliberate split/placement plan.
Recommended next steps:
  1. Decide board partition: separate ESC PCB + PM PCB, or one combined board within 60 × 200 mm.
  2. Finish the ESC schematic power stages and support passives.
  3. Set the board outline(s) to the 60 × 200 mm limit.
  4. Then run structured PCB placement for PM high-current corridor, four motor stages, MCUs, connectors, and thermal sensors.
Choose separate boards
Finish ESC schematic
Set board outlines
Fix PM ERC
Plan component placement
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Schematic

Layout

Preview

ESC Power and Current Sizing Notes
User-Declared Motor Current
  • Maximum motor current: 36 A per motor.
  • Four motors total: 144 A aggregate worst-case if all motors hit max simultaneously.
Immediate Design Implications
  • Treat 36 A as the power-stage design input until continuous current and burst duration are known.
  • Each motor inverter needs MOSFETs, phase copper, connectors, current-limit sense path, and local bulk capacitance sized for at least the 36 A channel maximum with thermal margin.
  • The main ESC battery input path and power-management output feeding the ESC must be evaluated for up to 144 A transient aggregate current, unless firmware/current limiting intentionally prevents simultaneous maximum draw.
  • A single shared PCB trace is unlikely to be appropriate for the full aggregate current without very wide copper pours, heavy copper, bus bars, or distributed power entry.
Protection and Distribution Notes
  • Each downstream board output from the power-management board should have its own surge/current protection path.
  • ESC output protection must be sized separately from lower-current flight-controller and E/O camera outputs.
  • For the ESC path, protection device choice depends heavily on whether 36 A is continuous, burst, or stall current.
Open Inputs Needed Before Selecting MOSFETs/Connectors/Protection
  1. Continuous current per motor.
  2. 36 A burst duration and duty cycle.
  3. Motor voltage rating, KV, pole count, maximum RPM, and winding resistance if available.
  4. Cooling assumptions: prop wash airflow, enclosure, copper weight, heatsink allowance.
  5. Battery pack C-rating and expected maximum pack current.
  6. Whether firmware should enforce total current limiting across all four channels.

  • User-Declared Motor Current

  • Immediate Design Implications

  • Protection and Distribution Notes

  • Open Inputs Needed Before Selecting MOSFETs/Connectors/Protection