BMS Battery Monitoring Unit (BMU) Reference Design
An illustrative module-level battery monitoring unit design for C&I and residential energy storage: 16S cell voltage and temperature sensing with passive balancing, an isoSPI daisy chain up to the master BCU, and an independent isolated supply on the BMU side from a push-pull transformer. This page covers the function, selection notes and available VOOHU parts for all 18 component positions on the board.
Illustrative PCB ⇄ Schematic
The illustrative PCB shows placement and component positions; the schematic shows where VOOHU parts sit in the circuit. Both views share the same position numbers: 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 16-series cell sense lines enter the board through connector J1 with a fuse on each line, pass an RC filter and then the VOOHU sense-line common-mode chokes L1–L3 (WHLC-2012A-121T1), which suppress common-mode noise picked up on the long harness; the AFE inputs are clamped by the VOOHU ESD arrays D1/D2 (WHTA5V01P2C). Only two adjacent sense lines are drawn; how many lines the chokes and ESD arrays cover and the R/C values depend on your design.
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 Sense inputs | Sense-line connector + fuses | J1 | — | — | Non-VOOHU |
| 02 | A Sense inputs | Sense-line RC filter | RC1 | — | — | Non-VOOHU |
| 03 | A Sense inputs | Sense-line common-mode choke | L1 L2 L3 | Signal Line CMC | WHLC-2012A-121T1 | VOOHU |
| 04 | A Sense inputs | Sense-line TVS / ESD | D1 D2 | TVS / ESD | WHTA5V01P2C | VOOHU |
| 05 | B Sensing & balancing | AFE sensing & balancing IC | U1 | — | — | Non-VOOHU |
| 06 | B Sensing & balancing | Balancing resistor array + balancing MOSFETs | RB1 Q1 Q2 Q3 Q4 Q5 | — | — | Non-VOOHU |
| 07 | B Sensing & balancing | NTC temperature sensing interface | J2 | — | — | Non-VOOHU |
| 08 | C isoSPI isolated comms | isoSPI transceiver | U2 | — | — | Non-VOOHU |
| 09 | C isoSPI isolated comms | isoSPI isolation transformer (upstream) | T1 | BMS Isolation Transformers | WHS06601A0 | VOOHU |
| 10 | C isoSPI isolated comms | isoSPI isolation transformer (downstream) | T2 | BMS Isolation Transformers | WHS06601A0 | VOOHU |
| 11 | C isoSPI isolated comms | isoSPI differential-line common-mode choke | L4 L5 | Signal Line CMC | WHAC-3225B-201U4 | VOOHU |
| 12 | C isoSPI isolated comms | Daisy-chain port TVS / ESD | D3 D4 | TVS / ESD | WHALD30E2B | VOOHU |
| 13 | C isoSPI isolated comms | Daisy-chain connectors (upstream / downstream) | J3 J4 | — | — | Non-VOOHU |
| 14 | D Isolated power | Isolated power transformer (push-pull) | T3 | Push-Pull Transformers | WHST06K14A0 | VOOHU |
| 15 | D Isolated power | Isolated DC-DC controller | U3 | — | — | Non-VOOHU |
| 16 | D Isolated power | Output-filter molded inductor | L6 | Molded Inductors | WHYT0630 Series | VOOHU |
| 17 | E Local power | Input EMI filter (power-line common-mode choke) | L7 | Power Line CMC | WHAL-4520A-900T0 | VOOHU |
| 18 | E Local power | Current transformer (optional) | CT1 | Current Transformers | WHPT-EP070-020 | VOOHU |
Resources & downloads
Board bill of materials
Reference designators, zones, VOOHU categories, recommended parts and availability for all 18 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 BMU reference design full package
Includes the full board BOM, datasheets for the recommended VOOHU parts, and position-by-position selection notes. For selection advice tailored to your module's series count and topology, describe them in the requirements field. We reply within 24 hours on business days.
