What are the essential elements of a good schematic design document?

Besides common component symbols, we need symbols fully representing devices and their functions. All ICs and components of similar complexity are well-described in datasheets. Manufacturer representatives usually make a good job when creating symbols used in datasheets. We can inspire ourselves from their work.

An important thing to consider in labeling components in a schematic, which I found very important when dealing with the huge complexity of a satellite or particle detector design, is an "object-oriented" naming. When dealing with complex systems on PCBs, it may be that multiple PCBs are used on the same system, or more domains on the same board (RF, Analog, Digital, High Voltage, Etc..). i.e. RF_R1, RF_C2... ANALOG_C4, ANALOG_L5... Choosing a naming system that can work as object programming, i.e. identifying where a component comes from, can have a huge impact on routing and debugging. Additionally, the naming can imply the physical position of the component in the system. WEST_R8, EAST_IC2, T_L9 (top layer).

A good schematic design document in architecture should include conceptual sketches, floor plans, and elevations. It should articulate spatial relationships, preliminary materials, and proposed systems. It should cover the design intent, basic building shape, size, and circulation. Key features like site analysis, initial cost estimates, and sustainability goals should also be outlined for clarity.

Don't fall in this beginners' trap: a symbol is a functional/electrical representation, drawing a symbol following the component package is a non-sense. Especially when you want to re-use the symbols for other packages! IEC 60617 and IEEE 315 standards can help you normalize everything. Well-drawn symbols lead to good quality schematics, just like good footprints are the foundations for great PCBs.

Essential elements of a good schematic design document: 1. Clear Labels: Use consistent and descriptive component names and net labels. 2. Readable Layout: Keep the design neat, with components organized logically. 3. Component References: Ensure each component has a unique designator. 4. Pinouts and Connections: Clearly show all connections and pin assignments. 5. Power and Ground Nets: Label power and ground connections for easy identification. 6. Signal Flow: Arrange components to follow the signal path logically. These points ensure a clear, accurate, and professional schematic design document.

The hierarchical and left-to-right schematic flow are big helpers with comprehension. All ground symbols should point downward while all power supply symbols should point upward. These little details matter.

Good points from Petr below - I would suggest that negative supply rails would typically connect "downwards". Another thing that was drummed into me as a junior engineer is that nets should never be joined in a "cross", instead using two separated "Tee" connections makes it clearer.

A good schematic layout starts with high-level block diagrams, power architecture, and revision history. Organize the schematic by function, such as power, analog, and communication sections. Include PCB layout considerations like mounting holes, fiducials, and PCB stack information. Use proper sheet titles and maintain a left-to-right flow (input to output) for clarity. This approach enhances readability and ensures a logical structure, making it easier to understand and follow the circuit design.

A schematic flows left to right. Individual pins of connectors should be at the edges; reference designators would eliminate cumbersome long lines. Orientation examples: analog feedback components are horizontal, and digital pull-up components are vertical. Power supply voltage symbols and grounds are vertical. More subtle: a voltage divider could be drawn with R1 horizontal and R2 vertical. Components inside dual op-amps, quad gates, resistor packs, and similar should be distributed where used. The designator should imply which physical IC or package they are a part of. Page breaks should have logical demarcation points. Bonus: A functional block diagram! Dashed boxes in the schematic encompass each block. Add test points!

Adopting a hierarchical design approach is a highly effective practice for creating clear and organized schematic design documents. E.g. Altium has an inbound feature to use Sheet Symbols to establish parent-child relationships. It makes the design maintaining a logical flow, making it easier to understand and navigate. Hierarchical designs enhance readability by guiding signals from a child sheet up to a matching ports on the parent sheet.

Textual comments and well-chosen signal labels are used to describe the circuit function to our colleagues, firmware developers and manufacturer’s representatives.

Important signals, power lines, and ground should be labeled (e.g., VCC, GND, RESET). Naming nets improves readability and helps in debugging.

Don't hesitate to also add images, screen captures and links to documentation if appropriate. Modern ECAD software are able to handle them.

Annotations and comments in schematics provide crucial extra details. Annotations, like reference designators for components, help prevent confusion and ensure consistency. Inconsistent or missing annotations can lead to mistakes, so clear labeling is essential. For instance, block-based annotations (e.g., R_BUCK1_1) or numeric prefixes (e.g., Rx0001) can aid in identifying sections. Comments offer valuable insights, such as layout guides, design notes, calculations, and variant management. They enrich the schematic with configuration information, variant details, and system-relevant notes, ensuring a comprehensive and clear design.

For Schematic Debugging I will high recommend using Navigator Panel in Altium Designer: View -> Panels -> Navigator The Navigator panel in Altium Designer is like a map for your electronic design. It helps you explore the different parts of your project, showing the connections between them. This panel lets you look at either one specific part or all the parts together. It uses a model that's created when you compile your project, making it easier to find your way around. You can also use it to check out the different components, connections, and pads on the actual circuit board. It's a handy tool for navigating through your project and understanding how everything is connected.

Always run an ERC (Electrical Rules Check) at the end! This is what the compiler is to software programming. It can save you from manufacturing a faulty design!

For schematic capture, it's crucial to use properly configured tools and ensure consistent settings, especially when multiple people are involved. Capturing the schematic from left to right (input to output) provides a clear understanding of the design flow. Running a Design Rule Check (DRC) after capturing helps identify open connections and unconnected nets. Verification should focus on both functionality and tool-based checks. After completing the schematic, netlist verification and functionality-wise simulations are essential to ensure correctness and accuracy. These steps are vital for a reliable and error-free design.

Below I am listing all the Key Docs you can prepare Before, During and After Finishing your Electronics Hardware Design Project: 1. Project Specification Document 2. System Architecture Blocks 3. Hardware Requirements Specification (HRS) 4. Power Budget and Thermal Analysis (We do that before Layout and After Layout) 5. Schematic Notes, BOM, Manufacturer Notes, Production Data. 6. Risk Analysis Document 7. Cost Estimate Document 8. Board Bring Up (Power Off, Power On, With and Without Firmware) 9. Bugs and Mitigations 10. Revision Control and Change Log

Proper naming in documentation is crucial, and establishing a baseline of the documents is very important. Key documents include HWRS, HDD, schematic, layout input file, WCCA, layout, library files, and Gerber data. Providing a comprehensive revision or review history, including all comments, aids in future reference. Establishing version-controlled files, like using Git or SVN, is vital for audits. While working with different formats can be challenging, using third-party importers/exporters may cause issues. It's better to use a well-set environment suite with all the necessary tools for the design cycle. If multiple people are involved, ensure consistent formats across the team.

Must-to-check 1.Symbol verification w.r.t. datasheet 2.BoM verification 3.DRCs & netlist verification 4.Check for unused pin termination 5.Power sequencing is as per power tree 6.If any special requirements are mentioned in datasheet check if they are followed. 7.PU & PD wherever required 8.Default state for critical signals should be provided 9.Voltage should be same for a net on driving & receiving end Good-to-have: -Block diagram -Major Revision history -Highlight PWR & GND nets, to avoid any shorting -Give appropriate net name -Mention current ratings & directions on power nets, impedance for high-speed and differential signals, and other imp layout notes for layout review. -TP for imp PWR & GND (preferable TH or one on top and bottom)

A good schematic should have the below line items 1. High Level Block Diagram of the system. 2 Manufacturer approved stackup. 3 Crtical Signals labelled with required impedance, clock speed and reference link for datasheet if any layout guidelines are recommended from manufacturer. 4 Power Tree with current rating for all voltages. 5 Any specific DFA/DFM guidelines from manufacturer. 6 Test points placement instructions (Top/Bottom side). 7 BOM can be optional 7 Compliance and Regulatory information

1. EMI-EMC tests 2. DFM analysis 3. FCC test plan 4. Critical components assembly instructions 5. High level Block diagram 6. Power tree 7. Accessories requirements - cables, connectors, shield, enclosures

A well captured schematic should be self-explanatory: - the comprehension of the signal and power flows must be straightforward - the calculations of component values, cut-off frequencies, etc. should be written next to the function/component - the needed additional documentation should be linked/mentioned Sometimes, being clear and concise takes some more time. And space: don't hesitate to take much space on the page to make things clear.

A schematic should aid understanding by design engineers and add value to service technicians, but it is primarily a conceptual diagram if we read it to understand functionality. It is often a trade-off of conceptual vs. physical, i.e., "understanding" vs. "repairing". Regardless, there is value to the upfront work to provide clarity as there are time savings for the many engineers and technicians who would read it later. Ultimately, we are trading preparation time for overall usefulness. Let's also say we can create many rules or tips, but consistency over the entire schematic creation is the most important.