PCB Design for Fog Generator
Worked
Stopped by execution credits before I could finish the full schematic update or run ERC.
Completed so far:
- Removed obsolete 14 V parallel ideal-diode mux parts: U10/U11, Q10/Q11, C1/C2, R1–R4.
- Removed old TPS563200 17 V buck section: U3, L1, C5–C9, R5–R7.
- Removed old pump MOSFET driver and 2-pin pump connector: Q2, R16, R17, D2, J4.
- Renamed global power nets:
+14V_BUS→+28V_BUS+14V_MUX→+28V_OR_PRE_FUSEVBAT_A_IN→VBAT_SERIES_INPUMP_PWM→STEPPER_STEP
- Added main new 28 V architecture parts:
- U_BB LM5175PWPT buck-boost controller
- U3 TPS54561DPRT wide-VIN 3.3 V buck regulator
- J12 logical 6-pin LEMO input connector
- J4 5-pin JST-XH stepper pump connector
- U_DIODE_1/U_DIODE_2 LM74700-Q1 ideal-diode OR controllers
- Q_DIODE_1/Q_DIODE_2/Q_BB1–Q_BB4 using TSM170N06CP_ROG 60 V / 38 A MOSFETs as library substitutes because FDP18N40 was not found
- L_BB 47 µH / 15 A generic inductor placeholder
- Added and partially wired:
- LEMO input filter caps
- LM5175 bootstrap, soft-start, compensation, RT, UVLO, and feedback passives
- LM74700 1 µF VCAP bypass caps and gate networks
- TPS54561 input/output caps, bootstrap cap, feedback divider, EN/UVLO, SS, RT, and compensation placeholders
- Stepper connector pins for
+28V_BUS,GND,STEPPER_STEP,STEPPER_DIR,STEPPER_ENABLE
- Updated existing metadata:
- C3 to 4700 µF / 50 V bulk
- C4 to 50 V HF bypass
- F1 marked 25 A / 50 V minimum requirement
- J3 heater label/role updated for 28 V 200 W
- Q1 metadata updated to the 60 V MOSFET substitute
Important unresolved items:
- ERC has not been run after these edits.
- LM5175 datasheet correction: LM5175 VIN max is 42 V, not 60 V. It may still work for a 28 V system, but it is not a 60 V input controller.
- The exact LEMO EGG.1B.306 library footprint was not found; J12 is currently a logical 6-pin connector placeholder.
- The LM5175 current-sense implementation is only placeholder-wired; the proper high-power current-sense resistor/network still needs detailed design.
- INA226 monitor wiring is not fully resolved after the architecture change; U6B/R21 are still in an intermediate/orphaned state and need reconnection to the intended +28 V measurement point.
- PCB layout is now invalid for this revised architecture and will need a fresh placement/routing pass after the schematic is cleaned.
Clean unresolved issues
Run ERC/DRC
Find 60V controller
Find LEMO footprint
Design current sense
Refine this doc
Ask about this doc
DMX-512 Interface Notes
Block Added
- U5: MAX3485ESA+ 3.3 V half-duplex RS-485 transceiver.
- C21: 0.1 µF local bypass from U5 VCC to GND.
- J7: DMX IN XLR-5 harness representation for Neutrik NC5FD-LX-B.
- J8: DMX THRU XLR-5 harness representation for Neutrik NC5MD-LX-B.
- R24 + SJ1: 120 Ω selectable DMX termination, normally open unless SJ1 is bridged.
- R25 + C22: shield isolation network from XLR pin 1 shield/chassis to PCB GND using 100 Ω in series with 10 nF.
MAX3485 Connections
Table
| MAX3485 Pin | Net | Function |
|---|---|---|
| RO | DMX_UART_RX | Drives ESP32 GPIO18 |
| ~RE | DMX_DIR | Receiver enable, tied with DE |
| DE | DMX_DIR | Driver enable, tied with ~RE |
| DI | DMX_UART_TX | Driven by ESP32 GPIO21 |
| GND | GND | Logic ground |
| B | DMX_B | RS-485 inverting / DMX Data- |
| A | DMX_A | RS-485 non-inverting / DMX Data+ |
| VCC | +3V3 | Logic supply |
DMX-512 Polarity Confirmation
DMX-512 5-pin XLR primary data pair uses:
- Pin 1: Shield / common
- Pin 2: Data- connected here to DMX_B / MAX3485 B
- Pin 3: Data+ connected here to DMX_A / MAX3485 A
- Pin 4: NC in this design
- Pin 5: NC in this design
This matches the standard DMX512-A primary pair convention: pin 2 is data negative and pin 3 is data positive. Note that some RS-485/fixture documentation may use confusing A/B naming; this schematic treats
DMX_A as Data+ and DMX_B as Data- per the user's requested net naming.Connector Library Note
The exact Neutrik NC5FD-LX-B and NC5MD-LX-B parts were not available in the library. J7 and J8 are represented electrically by 5-position connector symbols for the off-board panel connector harness. Replace their footprints/mechanical parts with the exact Neutrik panel connectors during mechanical/layout integration if available.
Validation
ERC review after wiring reported no open errors or warnings for the DMX block.
Block Added
MAX3485 Connections
DMX-512 Polarity Confirmation
Connector Library Note
Validation
