Analyze Power Nets

When this skill is invoked, perform a full AI-powered analysis of the PCB to identify power nets and recommend track widths.

Step 1: Load and Extract Components

from analyze_power_paths import ( analyze_pcb, get_components_needing_analysis, classify_component, trace_power_paths, get_power_net_recommendations, format_analysis_report, ComponentRole )

components, pcb_data = analyze_pcb("path/to/file.kicad_pcb") unknown = get_components_needing_analysis(components)

Step 2: Auto-Classify Obvious Components

These are already handled automatically - no AI needed:

Prefix Role Reason

R (resistor) SHUNT Pull-ups, voltage dividers

C (capacitor) SHUNT Decoupling caps

L (inductor) PASS_THROUGH Series filter element

FB (ferrite bead) PASS_THROUGH Series filter element

F (fuse) PASS_THROUGH Series protection

LED CURRENT_SINK Consumes current

SW (switch) PASS_THROUGH Power switching

Step 3: AI Analysis for Unknown Components

For each component in the unknown list, you MUST:

3a. Identify What It Is

Use WebSearch to look up the component:

WebSearch: "<part_value> <footprint_hint> datasheet"

Examples:

• "DB9 connector pinout"

• Is it signal or power?

• "1N4004 diode datasheet"

• Rectifier vs signal diode

• "3906 transistor datasheet"

• Power switch or signal amp?

• "LT1129 regulator datasheet"

• Voltage regulator specs

• "MCF5213 power consumption"

• IC current requirements

3b. Determine Its Role

Based on the datasheet/search results, classify as:

Role Criteria

POWER_SOURCE Supplies current to the board: power jacks, battery connectors, regulator outputs, USB power inputs

CURRENT_SINK Consumes significant current: ICs, MCUs, CPLDs, FPGAs, motor drivers, high-power LEDs

PASS_THROUGH Current flows through it: power switches, transistors used as switches, protection diodes in series

SHUNT Branches off the power path: ESD protection diodes, TVS diodes, signal connectors

3c. Estimate Current Rating

From the datasheet, find:

• For ICs: Total supply current (ICC, IDD)

• For regulators: Maximum output current

• For connectors: Expected load current

3d. Apply Classification

classify_component(components, 'J201', ComponentRole.POWER_SOURCE, current_rating_ma=1000, notes="DC barrel jack - main power input")

Step 4: Key Components to Analyze

Focus AI analysis on these component types:

Power Input Connectors (J*, P*, TB*, CN*)

• Question: Is this a power input or signal connector?

• Look for: Connection to power nets, barrel jack footprints, terminal blocks

• Classify as: POWER_SOURCE if it brings power onto the board

Diodes (D* followed by digit)

• Question: Protection diode, rectifier, or LED?

• Look for: Part number (1N4004 = rectifier, BAT54 = Schottky, LED = LED)

• Classify as:

• SHUNT if reverse protection (cathode to power, anode to GND)

• PASS_THROUGH if series rectifier in power path

• CURRENT_SINK if LED

Transistors (Q*)

• Question: Power switch or signal amplifier?

• Look for: Connections to power nets, gate/base drive signals

• Classify as: PASS_THROUGH if switching power, SHUNT if signal

ICs (U*)

• Question: How much current does it consume?

• Look for: ICC/IDD in datasheet, number of I/O pins

• Classify as: CURRENT_SINK with appropriate current rating

• Note: Regulators are auto-detected by power_out pins

Voltage Regulators (VR*, or U* with regulator part number)

• Question: What is the maximum output current?

• Look for: Output current spec in datasheet

• Classify as: POWER_SOURCE with max output current

Step 5: Trace Power Paths

After classifying all components:

paths = trace_power_paths(pcb_data, components) recommendations = get_power_net_recommendations(pcb_data, components, paths)

Step 6: Generate Report

print(format_analysis_report(pcb_data, components, paths, recommendations))

Provide the user with:

• Summary of component classifications

• Traced power paths showing current flow

• Recommended power nets and track widths

• Ready-to-use --power-nets command line arguments

Example Analysis Session

When analyzing a board like kit-dev-coldfire-xilinx_5213:

• J201 (JACK_2P): WebSearch "DC barrel jack 2.1mm" → POWER_SOURCE, 1000mA

• TB201 (CONN_2): Terminal block on same net as J201 → POWER_SOURCE, 1000mA

• D201 (1N4004): WebSearch "1N4004 datasheet" → Rectifier, but connected cathode-to-power → SHUNT (reverse protection)

• Q101 (3906): WebSearch "2N3906 PNP transistor" → Emitter on +3.3V → PASS_THROUGH (power switch)

• U102 (MCF5213): WebSearch "MCF5213 power consumption" → CURRENT_SINK, 200mA

• U301 (XCR3256): WebSearch "XCR3256 CPLD power" → CURRENT_SINK, 150mA

Output Format

Power Net Analysis for board.kicad_pcb

AI-Classified Components

Power Paths Traced

TB201 (power input) → SW_ONOFF201 → F201 → VR201 → +3.3V → U102 (MCU)

Recommended Power Nets

Routing Command

--power-nets "GND" "+3.3V" "/VDDPLL" "/VCCA" "Net-(TB201-P1)" --power-nets-widths 0.5 0.5 0.3 0.3 0.5

Important Notes

• Do not rely on component reference prefixes for ICs, connectors, or transistors - always look up the actual part

• Check net connections - a connector on a power net is likely a power connector

• Trace upstream - if a component feeds into a known power net, its input is also a power net

• Ground nets are always power nets - include GND, GNDA, AGND, VSS, etc.