48V Low-Voltage Servo Drive Reference Design
An illustrative 48V low-voltage servo drive mainboard design for AGV / AMR drive wheels, collaborative robot joints and small automation equipment: DC 24 ~ 48V input, driving a 400W-class permanent-magnet synchronous servo motor, with an EtherCAT dual-port slave, an RS-485 absolute encoder interface, an isolated RS-485 debug port, a Type-C tuning port, STO safe torque off and optocoupler-isolated I/O. This page covers the function, selection notes and available VOOHU parts for 31 component positions.
Illustrative PCB ⇄ Schematic
The illustrative layout shows placement and component positions; click any position to see its selection notes, recommended parts and package. The board view is an illustration neatly arranged by functional zone (not the actual layout); the EtherCAT ports, encoder, I/O and motor / power terminals sit along the bottom edge, and the servo motor is an external node.
The EtherCAT IN and OUT ports are identical, so the diagram shows 1 port and 1 differential pair (the other 10/100 pair is the same). J1 is a dual RJ45 with integrated magnetics and common-mode chokes; the PHY-side pairs are clamped by ESD arrays D1 / D2 and go to the JL1111BI-NI (EtherCAT-version PHY), which connects over MII to the slave controller (ESC); the ESC connects to the servo MCU over PDI. Center-tap wiring, termination and crystal load capacitor values per the PHY datasheet.
Board bill of materials
Click any row to jump to that position and view its selection notes
| No. | Zone | Position | Ref. | VOOHU category | Recommended part | Availability |
|---|---|---|---|---|---|---|
| 01 | A EtherCAT ports | Dual RJ45 (integrated magnetics, EtherCAT IN / OUT) | J1 | RJ45 Connectors | SYT212B579CD2A4D | VOOHU |
| 02 | A EtherCAT ports | Ethernet ESD array ×2 | D1 D2 | TVS / ESD | WHALD03G4U | VOOHU |
| 03 | A EtherCAT ports | EtherCAT 10/100 PHY ×2 | U1 U2 | Ethernet PHY | JL1111BI-NI | VOOHU |
| 04 | A EtherCAT ports | PHY 25MHz crystal | Y1 | — | — | Non-VOOHU |
| 05 | B Encoder · Comms | Encoder interface / RS-485 debug port | J2 J3 | — | — | Non-VOOHU |
| 06 | B Encoder · Comms | Bus ESD ×2 | D3 D4 | TVS / ESD | WHALD30E2B | VOOHU |
| 07 | B Encoder · Comms | Bus signal-line CMC ×2 | L1 L2 | Signal Line CMC | WHAC-3225B-510U0 | VOOHU |
| 08 | B Encoder · Comms | Encoder RS-485 transceiver | U3 | — | — | Non-VOOHU |
| 09 | B Encoder · Comms | Isolated RS-485 transceiver | U4 | — | — | Non-VOOHU |
| 10 | C I/O · Tuning | I/O · STO terminal | J4 | — | — | Non-VOOHU |
| 11 | C I/O · Tuning | Digital I/O optocoupler | U5 | — | — | Non-VOOHU |
| 12 | C I/O · Tuning | STO safe torque off circuit | U6 | — | — | Non-VOOHU |
| 13 | C I/O · Tuning | USB Type-C tuning port (USB 2.0 only) | J5 | USB / Type-C | WHTCAX01167303 | VOOHU |
| 14 | C I/O · Tuning | USB ESD array | D5 | TVS / ESD | WHTA5V01P2C | VOOHU |
| 15 | D Power stage · Motor | Three-phase gate driver | U7 | — | — | Non-VOOHU |
| 16 | D Power stage · Motor | Three-phase bridge MOSFET ×6 | Q1 Q2 Q3 Q4 Q5 Q6 | — | — | Non-VOOHU |
| 17 | D Power stage · Motor | Phase current sensing (shunt resistors + current amplifier) | U8 R1 R2 R3 | — | — | Non-VOOHU |
| 18 | D Power stage · Motor | DC bus capacitor bank | C1 | — | — | Non-VOOHU |
| 19 | D Power stage · Motor | Motor UVW · brake terminal | J6 | — | — | Non-VOOHU |
| 20 | E Core | EtherCAT slave controller (ESC) | U10 | — | — | Non-VOOHU |
| 21 | E Core | Servo control MCU | U9 | — | — | Non-VOOHU |
| 22 | E Core | Parameter storage Flash | U11 | — | — | Non-VOOHU |
| 23 | E Core | MCU crystal | Y2 | — | — | Non-VOOHU |
| 24 | E Core | Core supply filter molded inductor ×2 | L3 L4 | Molded Inductors | WHYTA0420 Series | VOOHU |
| 25 | F Power | DC 48V input terminal | J7 | — | — | Non-VOOHU |
| 26 | F Power | Input fuse + TVS | F1 D6 | TVS / ESD | WHTB058VA | VOOHU |
| 27 | F Power | Power line common-mode choke (EMI) | L5 | Power Line CMC | WHAL-1513A-301T0 | VOOHU |
| 28 | F Power | Synchronous buck ×2 (48V→12V→3.3V) | U12 U13 | — | — | Non-VOOHU |
| 29 | F Power | DC-DC molded inductor ×2 | L6 L7 | Molded Inductors | WHYT1030 Series | VOOHU |
| 30 | F Power | Push-pull isolated power transformer | T1 | Push-Pull Transformers | WHST06K14A0 | VOOHU |
| 31 | F Power | Push-pull driver + isolated-side LDO | U14 U15 | — | — | Non-VOOHU |
Resources & downloads
Board bill of materials
Reference designators, zones, VOOHU categories, recommended parts and availability for all 31 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 servo drive reference design full package
Includes the BOM, datasheets for the recommended VOOHU parts and position-by-position selection notes. For selection advice tailored to your bus voltage, motor power or fieldbus protocol, please include it in your requirements. We reply within 24 hours on working days.
