Isolated SPI
Controller
Like any integrated circuit the controller will need some peripheral components to make it run properly
Common Mode Filter
On differential datalines, a CMC filters common mode noise without affecting the useful signal.
MLCC - Multilayer Ceramic Chip Capacitor 50 V
This Capacitor increases common mode rejection by balancing the center tap of the transformer. Depending on the PHY’s architecture, the circuitry around the termination resistors can be different.
Signal Transformer
The Signal Transformer has two functions in this application. First, the single-ended signal is transformed to a balanced System to improve Immunity. Second, the participating systems are electrically isolated from each other to avoid potential equalization. Depending on your Application we can offer different isolation and working voltages.
Modular Jack
Wählen Sie SMT-, THT- oder THR-Typen für eine optimierte Verarbeitung. Zudem haben wir 45°, vertikale und horizontale Varianten. Angepasst an Ihre Anforderungen bieten wir unserere Modular Jacks in ungeschirmt, halbgeschirmt und vollgeschirmt an. Ein breites LED Angebot rundet unser Portfolio ab.
D-SUB Steckverbinder
Wir können Sie mit dem bekannten D-Sub-Steckverbinder unterstützen. Weibliche und männliche Varianten und auch abgewinkelte und nicht abgewinkelte Typen können angeboten werden. Das Portfolio wird durch passende Kabelvarianten abgerundet.
Rundsteckverbinder
Steigen die Anforderungen an den Steckverbinder führt oft kein Weg an Rundsteckverbinder vorbei.Diese sind in der Industrie, besonders in der Mess- und Steuerun0gstechnik, sowie in der Leistungsversorgung zuverlässige Verbindungen in vorallem schwierigen Umgebungen.
Terminal Blocks
Um auch unsere Kunden im industriellen Umfeld bestmöglich unterstützen zu können, bieten wir eine breite Auswahl an Terminal Blocks an. Fertigungstechnologien wie THT, THR und SMT werden von unseren Produkten abgedeckt.
Short Introduction to Isolated SPI
To transmit data between ICs within a system, on-board interfaces like I²C or SPI are well suited. However, if the communication is conducted over several boards, or even over longer distances, a galvanically isolated, differential solution is required. Isolated SPI offers a simple and low effort solution for this.
In case there is a high potential difference between transmitter and receiver, i.e. in battery management systems, then there are higher requirements for the galvanic isolation between the devices. For these use cases we can offer special signal transformers.
Learn More About Isolated SPI
Transformer for Battery Management Systems With Integrated Common Mode Choke
Transformer for Battery Management Systems With Integrated Common Mode Choke
The WE-BMS series isolates the serial-connected components of the battery pack and the following BMS controllers from each other, suppressing any voltage differences and EMI that may occur. The design from Würth Elektronik provides a much larger physical creepage distance as opposed to other competitors, following market requirements for this kind of applications.
By maintaining the physical distance through the innovative design regardless of coated traces, high system safety and reliability can be achieved through special robustness against dryness or heat. Fully insulated wires are used for flat design and even better isolation properties.
Thanks to the innovative construction, a larger physical creepage distance can be achieved with the same size as with the conventional design.
The included transformers and common mode chokes ensure BMS isolation and suppress electromagnetic interference for reliable signal transmission.
The WE-BMS series supports serial Daisy Chain, isoSPI, SPI and other signal isolations. Single and dual transformer for one or two channels are available.
BMS Layout Guidelines
The signal lines should be kept as short as possible and the transformer should be as close as possible to the isoSPI cable connector. A distance of <2 cm is suggested.
IC should be placed between 1-2 cm from the transformer to avoid magnetic coupling.
For four-layer or multilayer PCBs, the area around the BMS traces, the BMS socket and the transformer should be exposed in all layers. The distance around this area to copper surfaces and traces should be at least 4 mm, depending on the system working voltage.
From the Smallest to the Largest Applications
The transformers with 1000 VDC working voltage are suitable for smaller energy storage systems such as consumer energy storage and for applications with lower voltages such as 600 VDC
BMS transformers with a working voltage of 1500 VDC and a test voltage of 6400 VDC are available for applications with large battery packs, such as in energy storage systems for solar and wind farms.
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![Graph that shows how a battery management system works]( "WE-BMS Block Diagram")
A BMS is an electronic system that manages a rechargeable battery with the goal to make it safe and reliable.
Functions of a BMS:
- Protecting the battery from operating outside its safe operation area
- Monitoring its state of charge and state of health
- Calculating secondary data and reporting that data
- Controlling its environment
- Authenticating it and/or balancing it
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![Graph that explains why a transformer is needed in a BMS]( "Why is a transformer needed in a BMS?")
The individual cells in a battery pack are connected in series as well as the following BMS controllers. Between the components or PCBs connected in series, voltage differences and electromagnetic interference can occur. A transformer can be used to insolate the components from each other and suppress EMI interference. Therefore, WE-BMS transformer supports the BMS isolation and EMI noise suppression for a safe and reliable operation.
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![WE-BMS Partial Discharge Test]( "WE-BMS Partial Discharge Test")
Partial discharges are localized dielectric breakdowns. Fixed insulation in which partial discharges occur during operation is not permitted in the long term.
To ensure the long term reliability of the insulation, Würth Elektronik carries out the partial discharge test in accordance with IEC 60664-1.
The test is passed if the quantity of partial discharges is below a limit value of 10 pC (pico coulomb).
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![Graph that explains the isoSPI and SPI relation with a middle pin]( "WE-BMS Transformer Center Tab")
The Würth Elektronik product portfolio offers transformers with and without a center pin. In addition to the integrated common mode choke in the transformer module, the center pin contributes to the suppression of common mode interference. For this purpose, a bypass capacitor is connected to the center pin, which provides a low impedance ground connection for common mode interference and thus diverts it towards earth. This leads to an improvement in isoSPI performance. Please refer to the IC manufacturer's data sheet for the selection of capacitors.
