CM4 94V‑0 Schematics — Full Write-up

2. How to Identify Your Specific Board

Since many manufacturers use the "CM4" label and the "94V0" mark, you must look for the Manufacturer Logo or a specific Model Number printed on the PCB (usually in white silkscreen).

Common Manufacturers & Naming Conventions:

• Waveshare: Look for a logo that resembles a sound wave. Model numbers often look like CM4-IO-BASE-A, CM4-IO-BASE-B, or CM4-NANO-A.
• Geekworm: Look for the Geekworm logo. Model numbers often start with x (e.g., x1200, x1300).
• Seeed Studio: Often rebrands the "reComputer" or Odyssey series carrier boards.
• Generic/Amazon/AliExpress: If the board has no logo, it is likely a generic carrier board. These usually follow the standard Raspberry Pi Pi 4 Model B pinout layout.

7) Closing / next steps

• Start from the official CM4 reference schematics; adapt power and IO sections to your application while preserving recommended routing and decoupling.
• Validate your carrier board with an early prototype and measure power rails, signal integrity on high-speed lanes, and verify boot behavior before mass production.

If you want, I can produce a concise BOM, power‑rail schematic checklist, or sample symbol/pin mapping for a specific CM4 variant (specify RAM/boot/eMMC/wireless options).

Here’s a practical, useful post for engineers or hobbyists working with the CM4 (Raspberry Pi Compute Module 4) on a 94V-0 rated PCB (flame-retardant board, common for commercial products).

Part 7: From Schematics to Certified Product – The 94V0 Path

Having a great schematic is only half the battle. To achieve UL94 V-0 certification for your final CM4 product:

1. Design – Follow the rules above.
2. PCB fabrication – Order from a UL-approved supplier (e.g., PCBWay, JLCPCB, Advanced Circuits) with explicit 94V0 series number.
3. Assembly – Use 94V0-compliant solder mask and legend ink.
4. Testing – Perform a vertical flame test per UL94 (or request a lab test for certification).

Cost impact: 94V0 FR-4 adds ~5-10% to board cost compared to non-rated material – negligible for production runs.

1. 94V-0 Doesn’t Change the Schematic – But Does Change Layout

• 94V-0 is a PCB flame rating (UL94), not an electrical spec. Your schematic remains identical to a standard CM4 carrier.
• However, 94V-0 often implies higher creepage/clearance requirements (e.g., for AC mains or battery-powered products). Plan for wider traces/spacing early – it affects component placement.

B. If it is a Raspberry Pi Official IO Board

If your board is large, black, and officially branded Raspberry Pi:

• Schematic Location: The official schematics are hosted on the Raspberry Pi website under "Compute Module 4 IO Board".

Clearance and Creepage

A schematic destined for a 94V0 PCB must have explicit "net classes" for high voltage.

• Example: If your carrier board accepts 24V industrial power (stepped down to 5V), the 24V nets must have a clearance of 1.5mm to 3.0mm from low voltage nets.
• Schematic Annotation: You will often see a note in professional schematics: "Design meets IEC 60950-1 / UL 94V-0. Maintain 1.2mm creepage between Primary and Secondary sides."