Power supply design is one of the most critical — and most failure-prone — modules in PCB design.
Have you ever experienced these situations?
The power supply overheats as soon as it powers up?
The routing looks clean, but there's always interference?
You can't understand the datasheet's recommended layout, and don't know where to place components?
In reality, power supply design isn't as complex as you might think. Master the key principles, understand the schematic, and half the design is done.
This guide breaks down switching power supply and LDO linear regulator PCB design techniques — from layout to copper pour, from GND handling to via placement.
A typical switching power supply module consists of the following parts:
| Component | Function |
|---|---|
| DC-DC Converter Core | Responsible for power conversion |
| Output Sampling Circuit (R1, R2) | Samples voltage and feeds back to the comparator |
| PWM Error Amplifier & Driver Circuit | Controls output voltage by adjusting duty cycle |
The feedback resistors compare the output voltage with the reference voltage Ur. The PWM controller adjusts the duty cycle, thereby regulating the output.
Referencing the manufacturer's recommended layout is critical — especially the placement of input/output capacitors, inductors, and MOSFETs.
Keep the main current path clear; prioritize core routing:
Center the layout around the switching chip and its pins
Avoid placing input and output filter capacitors side by side to prevent input noise coupling to the output
Reserve sufficient copper pour and via space
Arrange components in a consistent direction
Minimize connection length and via count
Core filter capacitors must be close to the pins — don't place them randomly!
Compact layout = small parasitics + low EMI + good heat dissipation
Common ground and power input/output lines must be wide or copper-poured
Signal interconnect traces should be at least 10 mil (most engineers recommend 12–15 mil)
Route high-current loops on the top or bottom layer to prevent layer breaks
| Pin | Routing Requirement |
|---|---|
| SENSE Line | 0.5mm trace width, connect to the output capacitor terminal, avoid power components; do not route directly from the chip pin |
| GATE Drive Line | Keep it short and thick; do not route close to high-frequency signals |
| INTVCC Filter Capacitor | Must be placed close to the chip to provide the GATE current supply path |
No routing beneath the chip and inductor — add thermal vias
All chips with a Power Pad require opening + copper pour + thermal vias
No signal lines beneath the inductor to prevent magnetic interference coupling
For multi-output designs, place adjacent inductors perpendicular to reduce mutual interference
Do not fully connect! Leave a "thermal relief path" for soldering
Large copper areas should not rely on a single via for grounding — use a via array
Copper pour without thermal relief can cause cold solder joints, solder bridging, and tombstoning
LDO stands for Low Dropout Regulator.
Suitable for: 3.3V → 1.8V, 5V → 3.3V, and other low-voltage step-down applications
Features: Simple structure, fast power-up, low ripple, stable output
Limitations: Step-down only; output current generally does not exceed 2A
Input/output capacitors close to the chip pins
Place the large capacitor first (e.g., 10µF), then the small capacitor (e.g., 0.1µF)
Main current path should be straight and thick
Use the shortest path possible to avoid additional voltage drop
GND main return routing
GND pins should connect to a large copper area to increase conduction area
Place multiple vias — quantity based on input/output routing
Connect input and output grounds together to form a closed loop
Master these, and power supply design won't be a concern!
| Design Aspect | Switching Power Supply | LDO |
|---|---|---|
| Control Method | Duty cycle control | Linear control |
| Input/Output Layout | Inline layout, close to chip | Large capacitor first, then small |
| High-Current Routing | Copper pour or ≥20 mil | Widen the main path |
| GND Handling | Single-point ground + multiple vias | Large copper area + multiple vias |
| Thermal Recommendation | Thermal ground vias + opening | Generally no additional heat dissipation needed |
Need Power Module PCB Design or Manufacturing Support?
AnyPCBA has extensive experience in power module PCB design and manufacturing, covering switching power supplies, LDO linear regulators, and multi-rail power distribution. Our manufacturing capabilities cover 2-64 layers, including HDI, rigid-flex, heavy copper, and high-frequency hybrid processes. Our engineering team provides DFM/DFA design reviews before production to help identify potential issues in loop layout, grounding strategy, and thermal design.
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