PCA9518DW - 5-Channel 400kHz I2C Hub | Texas Instruments
MPN: PCA9518DW ✓ نشطPCA9518DW نظرة عامة
An I2C hub is a specialized interface IC that buffers and divides one upstream I2C or SMBus segment into multiple downstream segments. The I2C protocol limits the total capacitance supported by a conventional bus to 400 pF, where the limit is determined by connected devices and cable length. The PCA9518 expands that usable bus by placing isolated buffer groups between the upstream pins and downstream channel pins, allowing additional devices to be connected without redesigning the upstream bus.
Key characteristics include five bidirectional downstream channels, operation across a 3 V to 3.6 V supply range, 400-kHz bus operation, and an expandable topology supported by the TI product family. Each downstream group buffers both clock and data in the forward direction while providing the return path required by the I2C protocol. The buffered arrangement also helps isolate capacitance between downstream segments rather than presenting every device directly to the upstream bus.
The PCA9518 is useful in systems where a host controller must reach multiple embedded subsystems, sensor boards, EEPROMs, power monitors, or other low-speed peripherals beyond the practical capacitance of one unbuffered bus segment. Because the device is a bidirectional buffer hub rather than a general-purpose GPIO expander, it does not add individual digital input or output ports. It preserves the two-wire serial protocol while changing the electrical segmentation of the network.
Typical uses include multi-board test equipment, industrial controllers, programmable instrumentation, server management boards, and modular sensor systems. The 20-pin SOIC package also supports conventional surface-mount assembly, although a footprint confirmation against the specific manufacturer ordering information is recommended before layout release because the verified data does not provide a complete pin table.
When laying out a design, treat every upstream and downstream SCL and SDA connection as a separate routed segment and place the hub close to the point where the bus must be divided. Keep stub lengths short on high-capacitance branches and follow the manufacturer layout guidance for pull-up placement. Because the verified sources describe the function, package, voltage range, frequency, and bus-capacitance segmentation but do not publish detailed pin assignments or timing tables, those specific values should be confirmed against the official PCA9518 datasheet before release.
بدائل مباشرة لـ PCA9518DW — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
الطرازات في هذه السلسلة
طرازات من نفس السلسلة متوافقة تمامًا مع PCA9518DW (نفس عامل الشكل والبصمة) — يختلف في Package.
PCA9518DWRG4
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
PCA9545ADGVRG4
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←PCA9518DW المواصفات
| Device Type | Expandable five-channel bidirectional I2C/SMBus buffer hub |
| Number of Downstream Channels | 5 channels |
| Supply Voltage Range | 3 V to 3.6 V |
| Maximum I2C Bus Frequency | 400 kHz |
| Protocol Support | I2C and SMBus |
| Signal Direction | Bidirectional |
| Maximum Bus Capacitance per Group | 400 pF |
| Bus Segmentation | Buffered SDA and SCL groups separated from the upstream bus |
| العلبة | 20-SOIC (0.295 inch, 7.50 mm width) |
| نوع التركيب | Surface mount |
| الفئة | Interface ICs - I/O expanders |
| عدد الدبابيس | 20 pins |
دليل تكوين أطراف PCA9518DW 20-soic (0.295 inch, 7.50 mm width)
تكوين الأطراف لـ PCA9518DW (حزمة 20-soic (0.295 inch, 7.50 mm width)). يتم تعريف ترقيم الأطراف والوظائف ومخططات التوصيل في ورقة البيانات الفنية من الشركة المصنعة. راجعها للحصول على البصمة الدقيقة وإرشادات اللحام.
لا تتوفر بيانات مفصلة لمخطط التوصيلات لـ PCA9518DW.
راجع ورقة البيانات للحصول على تكوين الأطراف الكامل.
التطبيقات النموذجية
PCA9518DW مناسب لـ 6 التطبيقs: Multi-Sensor I2C Bus Expansion, Programmable Instrumentation Backplane, Industrial Control Module Expansion, Server Management and Configuration Bus, Embedded Module-to-PCB Communication, Low-Speed Peripheral Isolation.
Multi-Sensor I2C Bus Expansion
The PCA9518DW fits systems that must connect several sensor groups beyond the capacitance of one conventional I2C segment. Its five bidirectional channels let a host communicate with separate downstream branches while the buffered SDA and SCL paths isolate each group from the full upstream bus. Because the device operates from 3 V to 3.6 V at up to 400 kHz, it suits 3.3 V pressure, temperature, acceleration, and environmental sensors that use standard I2C addressing. The design benefit is that each branch can be assessed against its own 400-pF capacitance limit instead of sizing the complete network as one segment. Short routed stubs, correctly placed pull-ups, and verification of the controller's bus timing remain necessary because five hub outputs do not remove loading from every attached peripheral.
موصى به
Programmable Instrumentation Backplane
The PCA9518DW is useful in modular test and measurement equipment where a controller must reach instruments across several circuit cards. Its five buffered downstream groups divide the I2C topology into separately managed segments, reducing the aggregate load presented to the controller side of the hub. The 400-kHz maximum bus rate accommodates standard I2C instruments and configuration interfaces, while the 3 V to 3.6 V supply range matches many mixed-signal and digital subsystems. A practical implementation places the hub near the backplane fan-out point and routes compact SDA and SCL branches to each card. Engineers should still calculate branch capacitance, select pull-up values for the actual rise time, and confirm the detailed pin and timing data in the official manufacturer datasheet before fabrication.
موصى به
Industrial Control Module Expansion
The PCA9518DW supports industrial control boards that connect distributed sensors, actuators, and identification circuits across a 3.3 V control domain. The buffered five-channel structure allows a controller to separate long or heavily populated cable branches rather than forcing all peripherals onto a single 400-pF-limited I2C segment. Its 400-kHz operation supports many common industrial peripherals, including temperature sensors, EEPROMs, ADC interface devices, and isolated monitoring components. Because industrial wiring often adds cable capacitance, keep downstream traces and connector stubs short, and place pull-ups only where required by the active segment. The hub does not provide galvanic isolation, so it should not be treated as a substitute for an isolated interface when common-mode voltage and ground-potential differences exceed the system budget.
موصى به
Server Management and Configuration Bus
The PCA9518DW can organize low-speed configuration traffic in server or storage management electronics, where a single management controller may need to reach several subsystems or peripheral cards. Five buffered I2C/SMBus groups help partition the topology and reduce the load seen on the upstream segment, while the 3 V to 3.6 V operating range aligns with common server-management logic. The 400-kHz limit suits EEPROMs, current monitors, sensors, and administrative controllers rather than high-throughput storage data paths. Place the hub near the physical bus split, route short branches to each subsystem, and avoid creating unnecessary stubs on unused channels. If a subsystem requires isolation, level translation, or substantially more bus bandwidth, use a dedicated interface for that portion of the system instead of overloading the hub's shared functional envelope.
موصى به
Embedded Module-to-PCB Communication
The PCA9518DW is appropriate when an embedded module communicates with several peripheral sections of a host PCB and the combined wiring exceeds the practical limits of one I2C branch. The device provides five bidirectional paths in a 20-pin SOIC package and operates at the standard 400-kHz fast-mode ceiling. This arrangement can shorten critical electrical distance by locating the hub close to the module connector, then dividing the load into downstream groups. Compared with adding software-configured GPIO for bit-banging, the buffered I2C approach preserves standardized clocking, addressing, and arbitration behavior. Layout quality remains decisive: verify pull-up values against segment capacitance and rise time, avoid long unbuffered stubs, and consult the official PCA9518 documentation for exact pin connections and layout guidance.
موصى به
Low-Speed Peripheral Isolation
The PCA9518DW can separate a host I2C segment from five groups of low-speed peripherals, reducing direct capacitive interaction between the upstream bus and downstream devices. This is valuable in systems combining long inter-board connections with short local sensor or memory branches, since each downstream group is buffered in both the clock and data directions. The bidirectional implementation preserves SMBus-style transactions, and the 3 V to 3.6 V supply range supports common embedded logic. It does not provide level shifting, galvanic isolation, or automatic bus-fault recovery beyond the behavior specified by the manufacturer. For noisy industrial environments or systems with different ground references, confirm that the hub remains within its absolute limits and add appropriate protection or isolation. Always check each segment's estimated capacitance against the 400-pF guidance before assigning devices.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ PCA9518DW — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | PCA9518DWRG4 | PCA9545AD |
|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 20-SOIC | 20-SOIC - same | 20-SOIC - same |
| Device Type | Expandable five-channel bidirectional I2C/SMBus buffer hub | Expandable five-channel bidirectional I2C/SMBus buffer hub | Four-channel I2C-bus switch with interrupt logic and reset |
| Downstream Channel Count | 5 channels | 5 channels | 4 channels |
أبرز الفروقات
- Provides five downstream buffered groups rather than four switch channels (مقابلPCA9545AD)
- Purpose-built expandable bidirectional buffer-hub architecture (مقابلPCA9545AD)
- Closest functionally identical listed ordering option (مقابلPCA9518DWRG4)
ملاحظات التصميم
Place the PCA9518DW close to the physical point where the I2C topology branches and keep each downstream SDA and SCL route short. The verified TI description states that buffered groups can operate within 400 pF, but this applies to each supported segment rather than to the complete network. Calculate device, connector, trace, and pull-up capacitance per branch, avoid long unused stubs, and confirm the actual branch configuration against the manufacturer's recommended layout before PCB release.
Route the 3 V to 3.6 V supply to the device with low-impedance planes or traces and place bypass capacitance close to the supply pins in accordance with the official datasheet. Do not rely on the I2C hub's buffered signal paths to remove supply noise; the SDA and SCL lines remain sensitive to voltage noise and excessive loading. Because the verified excerpts do not provide the specified bypass value, decoupling capacitance, current consumption, or absolute maximum ratings, obtain those values from the official PCA9518 datasheet before layout.
Do not treat the PCA9518DW as a GPIO expander or a level translator. It buffers and segments a bidirectional I2C/SMBus network but does not add discrete input or output ports, change logic voltage domains, or provide galvanic isolation. Also verify the exact ordering suffix and pin configuration: the supplied verified results identify a 20-SOIC package but do not include the complete pin table. Confirm upstream pins, downstream channel assignments, supply pins, enable behavior, and any unused-pin requirements directly from the manufacturer datasheet.
معلومات الامتثال
The verified excerpts identify the manufacturer, package, electrical function, voltage range, and bus frequency, but they do not contain explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals declarations. These fields remain unknown rather than being inferred.
