Inside most EV chargers, the electronics split into two printed circuit boards. The control board makes the decisions — it generates the pilot signal the car reads, watches the sensors and runs the display and communications. The power board does the mains-side work — driving the relay or contactor, powering the electronics and sensing the current. Where the two sides meet sits an isolation barrier, and that barrier is one of the most safety-relevant features on either board.
Key Takeaways
- The control board decides; the power board executes — and compact designs may merge both zones onto one PCB.
- Isolation is a physical barrier on the board, built with isolating components and verified creepage and clearance distances.
- User interfaces and communications belong on the isolated side of that barrier.
- Ask for board photos, coating confirmation, revision change control and the test report for the exact model.
Two Boards, Two Jobs
| Control board | Power board | |
|---|---|---|
| Main parts | Microcontroller, pilot-signal circuitry, display drivers, radio and RFID interfaces | Relay or contactor drive, AC-DC supply for the electronics, current sensing, protection front-ends |
| Works with | Low-voltage logic signals and the car’s control pilot | The mains supply and the switching device |
| Decides | How much current the car may draw, when to start and stop, what to display | Executes the switching and feeds measurements back to the control side |
Not every charger uses two physical boards. Compact portables often place both zones on a single PCB, separated into mains and low-voltage areas. The board count is a design choice; the separation between the zones is not.
The Signals the Boards Manage
- Control pilot: the signal telling the vehicle how much current is available; the board generates it and reads the car’s response.
- Connection and temperature sensing: inputs from the connector and temperature sensors, which can order a stop or a reduction.
- Residual-current sensing: the protection module’s signal arrives at the board, which trips the switching device.
- Metering input: voltage and current measurements that become the energy figures on a display or in an app.
None of these signals is decorative. A board fault shows up as a charger that will not start, stops early, or misreports a session — which is why board quality is a service-life question, not just a price question.
Isolation: The Barrier Between Mains and Low Voltage
Galvanic isolation means no direct electrical path between the circuits connected to the mains and the low-voltage circuits on the user side. On a charger PCB it is built with components such as optocouplers, isolation transformers and isolated DC-DC converters, and shows in the layout as a clear separation zone with defined creepage and clearance distances.
Those distances are set by the safety standard the charger is tested against, and the laboratory verifies them on the board as tested — one reason a board revision can matter for certification. Displays, RFID readers and network ports belong on the isolated, low-voltage side, so a mains-side fault has no path through them to the user.
What a Brand Buyer Can Ask For
- Board photographs, both sides, for the exact model and revision — the isolation zone should be visible.
- Whether boards are conformally coated against moisture, and over which areas. Ask; do not assume.
- The change-control rule: how PCB revisions are approved, and whether you are notified before one ships.
- The test report and certificate naming the model and configuration, covering the boards as tested.
Our explainers on UL and ETL listing and EV charger certifications set out what those documents attest.
EVDANCE Models and Board-Level Questions
Smart features live on these boards. The EV-ACT3204PE 22 kW wallbox (RFID and app control, CE) and the EV-AC03201T dual-connector station (OCPP 1.6J, RFID) depend on control and communications design as much as on their power stages; their stated specifications are on their product pages. EVDANCE is a Shenzhen manufacturer founded in 2011, exports to more than 30 countries, and offers private label from 100 units with a 3-year warranty. Board-level questions go through the OEM and private-label programme or contact us.
Frequently Asked Questions
Can an EV charger work with a single PCB?
Yes. Many compact chargers combine both zones on one board. What matters is the maintained separation between the mains and low-voltage areas, and that the tested configuration matches what ships.
What does conformal coating do?
It is a thin protective layer over the board that resists moisture and dust, which helps in damp or outdoor installations. It is a specification to confirm for the exact model, not a default to assume.
Does a PCB change need new certification?
It can. Changes to safety-relevant layout or parts may require the laboratory to re-evaluate the product. Ask the factory before accepting a silent revision change.
Related Reading
- RCD Protection for EV Chargers: Type A, Type B and 6 mA DC Detection Explained
- UL and ETL Listing for EV Chargers: How NRTL Certification Works
- EV Charger Certifications Explained: CE, UKCA, UL, ETL, CB and What Buyers Should Ask For
- OEM and Private-Label EV Chargers: A Complete Guide for Brands
