Smart Meter / Grid-Tie CT Reference Design
An illustrative reference design for three-phase smart meters (anti-backflow / grid-tie metering) in the PV & ESS management and communication layer: three-phase voltages pass a divider and three-phase currents pass external grid-tie CTs into the metering IC, which reports power direction and energy in real time to the inverter and EMS over isolated RS-485 per DL/T 645 / Modbus; Modbus TCP models add Ethernet. The meter is powered by its internal AC/DC. The power-frequency metering CTs are external standard parts; this page marks the VOOHU parts available on the meter's communication board.
Illustrative PCB ⇄ Schematic
Illustrative top-side view arranged by functional zone (not the actual layout). Red numbered dots mark positions VOOHU can supply. Click a component on the board, an entry in the index below or a part in the schematic to see recommended parts and package pinouts on the right.
Illustrative metering topology: three-phase currents enter terminal J1 through the secondary leads of the external grid-tie CTs and pass sampling resistors into metering IC U2; three-phase voltages enter the metering IC through terminal J2 and divider network RN1; the MCU reads power direction and energy over SPI. One phase of each is drawn; all parts in this chain are non-VOOHU positions, and the power-frequency metering CTs are external standard parts.
Board bill of materials
Summarized by position; click any row to locate it on the board above.
| No. | Zone | Position | Ref. | VOOHU category | Recommended part | Availability |
|---|---|---|---|---|---|---|
| 01 | A Voltage / current sampling | External grid-tie CT input terminal | J1 | — | — | Non-VOOHU |
| 02 | A Voltage / current sampling | 3-phase metering IC | U2 | — | — | Non-VOOHU |
| 03 | A Voltage / current sampling | 3-phase voltage input terminal | J2 | — | — | Non-VOOHU |
| 04 | A Voltage / current sampling | Voltage divider network | RN1 | — | — | Non-VOOHU |
| 05 | B RS-485 ×2 (isolated) | RS-485 terminals ×2 (inverter / EMS) | J3 | — | — | Non-VOOHU |
| 06 | B RS-485 ×2 (isolated) | RS-485 GDT ×2 | GDT1 | GDT | WHGT090V1P0A | VOOHU |
| 07 | B RS-485 ×2 (isolated) | RS-485 CMC ×2 | L1 | Signal Line Common Mode Chokes | WHAC-4532A-510U0 | VOOHU |
| 08 | B RS-485 ×2 (isolated) | RS-485 ESD / TVS ×2 | D1 | TVS ESD | WHALD30E2B | VOOHU |
| 09 | B RS-485 ×2 (isolated) | Isolated RS-485 transceiver ×2 | U3 | — | — | Non-VOOHU |
| 10 | B RS-485 ×2 (isolated) | Push-pull driver + rectifier / LDO | U4 | — | — | Non-VOOHU |
| 11 | B RS-485 ×2 (isolated) | Push-pull isolation transformer | T1 | Push-Pull Transformers | WHST06K02A0 | VOOHU |
| 12 | C Ethernet (optional) | RJ45 (Modbus TCP models) | J4 | RJ45 Connector | WH56A31882021103 | VOOHU |
| 13 | C Ethernet (optional) | Ethernet (opt) GDT | GDT2 | GDT | WHGD090V1P0B | VOOHU |
| 14 | C Ethernet (optional) | 10/100 LAN transformer (high isolation) | T2 | LAN Transformers | WHSH16F01D4 | VOOHU |
| 15 | C Ethernet (optional) | Ethernet port ESD array (optional) | D2 | TVS ESD | WHALD03G4U | VOOHU |
| 16 | C Ethernet (optional) | 10/100 PHY | U5 | Ethernet PHY | JL1101BR-NI | VOOHU |
| 17 | D Control core | MCU (protocols + anti-backflow logic) | U1 | — | — | Non-VOOHU |
| 18 | E 12 V power | 12 V (in-meter AC/DC output) | J5 | — | — | Non-VOOHU |
| 19 | E 12 V power | Input power-line common-mode choke | L2 | Power Line Common Mode Chokes | WHAL-7060A-102T0 | VOOHU |
| 20 | E 12 V power | Buck converter (12 V → 5 V) | U6 | — | — | Non-VOOHU |
| 21 | E 12 V power | Buck converter (5 V → 3.3 V / core) | U7 | — | — | Non-VOOHU |
| 22 | E 12 V power | Molded inductors ×2 (DC-DC) | L3 L4 | Molded Inductors | WHYT0630 Series | VOOHU |
Resources & downloads
Board bill of materials
Reference designators, zones, VOOHU categories, recommended parts and availability for all 22 positions. Opens directly in Excel.
Datasheet collection
Datasheet PDFs for the VOOHU parts recommended on this board.
Design files & footprint library
Schematic, PCB, and VOOHU part footprints and 3D models.
Coming soonRequest the smart meter / Grid-Tie CT reference design full package
Includes the full-board position list, datasheets for the recommended VOOHU parts and position-by-position selection notes. For selection advice tailored to your wiring (three-phase four-wire / three-wire), CT specifications or communication protocol, please include it in your requirements. We reply within 24 hours on working days.
