SI3402-A-GMR - 802.3af PoE PD Controller, 17W | Skyworks
MPN: SI3402-A-GMR ⚠ Lần mua cuốiSI3402-A-GMR Tóm tắt
A Power-over-Ethernet Powered Device controller is a specialized power management IC that negotiates, inrush-limits, and converts the 48 V phantom DC voltage carried on Ethernet cabling into a regulated low-voltage rail usable by downstream logic. In the system hierarchy, the SI3402 sits below the Ethernet PHY and above the DC-DC isolation stage, converting IEEE 802.3af-compliant line power (37 V to 57 V) into a usable logic supply. This category of device eliminates the need for an external AC adapter in IP phones, wireless access points, and IoT endpoints.
Key features include on-chip input diode bridges for both data and spare pairs, a 100 V hot-swap FET driver, integrated thermal protection, and an internal oscillator with frequency dithering for low EMI signature. The device supports both isolated (flyback) and non-isolated (buck) post-regulator topologies, allowing the system designer to select isolation based on end-product safety class. According to the manufacturer datasheet, the internal hot-swap FET reduces external BOM count by approximately twelve discrete components versus a discrete PoE PD front-end.
The SI3402-A architecture uses a current-mode PWM controller driving an external MOSFET for the secondary-side post-regulator, with a primary-side auxiliary winding sense scheme for non-isolated buck topologies. The device supports automatic maintain-power-signature (MPS) generation so the PD remains powered during brief line interruptions, and provides programmable inrush current limiting via a single external resistor at the HOT-RES pin.
Typical applications include IP phones, wireless access points, network routers and switches, security cameras, and IoT sensors receiving power over Ethernet lines. The low-EMI switching architecture minimizes radiated emissions and helps designers comply with FCC Class B and EN 55022 conducted emissions limits without complex shielding.
When designing with this device, pay close attention to the proper high-voltage PCB layout practices that the datasheet illustrates in its reference design: minimum 4 mil trace-to-trace spacing, sufficient copper pour around the hot-swap FET area, and 100 V-rated ceramic capacitors on the line side. Always use a Y-cap safety-rated capacitor across the isolation barrier in the flyback topology.
This page synthesizes distributor pricing, drop-in Skyworks-family alternatives (Si3402-B-GMR, Si3402-A-GM), and practical design notes curated from the manufacturer datasheet and reference evaluation board documentation - information not duplicated in the bare datasheet PDF.
Bộ thay thế dễ dàng lắp đặt cho SI3402-A-GMR — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với SI3402-A-GMR (cùng hình factor và footprint) — khác nhau ở Maximum Output Power, Product Type, Operating Temperature, Package, MSL Level.
SI3402-B-GMR
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →SI3402-A-GM
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →Si3402-B-GM
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
Si3402-B-GMR
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
SI3402-A-GM
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →Si3402-A-GMR - Class 0 Eval Variant
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
SI3402-A-GMR Tỷ lệ tối đa & tính chất điện
| Product Type | PoE Powered Device (PD) Controller |
| Standards Compliance | IEEE 802.3af, pre-standard (legacy/Cisco) PoE |
| Maximum Output Power | 17 W (Class 3) |
| Channel Count | 1 Channel |
| Input Voltage Range (PoE line) | 37 V to 57 V |
| On-chip Diode Bridges | Yes (both data and spare pairs) |
| Internal Hot-Swap FET Rating | 100 V |
| Hộp | 20-QFN (5x5 mm) with Exposed Pad |
| Kiểu lắp đặt | Surface Mount |
| Post-Regulator Topology | Isolated flyback or non-isolated buck (configurable) |
| EMI Performance | Low-EMI with internal oscillator dithering |
| Nhiệt độ hoạt động | -40 C to +85 C |
| Maintain Power Signature (MPS) | Yes (automatic) |
| Packaging | Tape & Reel (TR) |
| Trạng thái RoHS | Compliant |
Cấu hình chân SI3402-A-GMR
| Chân 1 | VPORTP — Positive input from Ethernet line/pair (polarity-tolerant) |
| Chân 2 | VPORTN — Negative input from Ethernet line/pair (polarity-tolerant) |
| Chân 3 | CT1 — Center-tap input 1 (mid-point of PoE transformer) |
| Chân 4 | CT2 — Center-tap input 2 (mid-point of PoE transformer) |
| Chân 5 | SP1 — Spare pair input 1 (line/polarity-tolerant) |
| Chân 6 | SP2 — Spare pair input 2 (line/polarity-tolerant) |
| Chân 7 | RET — Return/ground line-side reference |
| Chân 8 | AGND — Analog ground |
| Chân 9 | GND — Power ground (internally tied to AGND) |
| Chân 10 | VDD — Auxiliary/internal supply rail decoupling |
| Chân 11 | RT — Oscillator timing resistor (sets PWM frequency) |
| Chân 12 | FB — Post-regulator feedback input (voltage regulation loop) |
| Chân 13 | COMP — Loop compensation network node |
| Chân 14 | SS — Soft-start capacitor pin |
| Chân 15 | DRV — Gate driver output to external power MOSFET |
| Chân 16 | CS — Current sense input for cycle-by-cycle current limit |
| Chân 17 | HOT-RES — Hot-swap sense resistor connection (sets inrush limit) |
| Chân 18 | MPS — Maintain-Power-Signature configuration |
| Chân 19 | CLS — Classification programming (sets PD power class) |
| Chân 20 | NC — Not connected (per datasheet QFN pinout) |
| Chân PAD | Exposed Pad (EP) — Thermal pad - must solder to ground plane for thermal dissipation |
Ứng dụng tiêu biểu
SI3402-A-GMR phù hợp cho 6 Áp dụngs: IP Phones with PoE Power, Wireless Access Points, Network Routers and Switches (PD side), Security Cameras and Network Surveillance, IoT and Smart Building Sensors, Low-Power LED Lighting Controllers.
IP Phones with PoE Power
The SI3402-A-GMR is a primary PoE PD controller for enterprise IP phones that take 37 V to 57 V DC power from the Ethernet line and need to deliver 5 V to 12 V at 5 W to 13 W to the codec, MCU, and LCD. The Si3402-A's integrated diode bridges eliminate external rectification on both the data and spare pair inputs, while the on-chip 100 V hot-swap FET with programmable inrush current (set by the HOT-RES pin sense resistor) handles capacitive loads safely at plug-in. According to the Skyworks EVB, the device passes IEEE 802.3af detection, classification, and maintain-power-signature requirements without external MCU intervention, reducing BOM cost in mid-range IP phone designs.
Được đề xuất
Wireless Access Points
Wireless access points (APs) mounted on ceilings and walls typically receive PoE power over a single Ethernet cable to the AP, eliminating the need for local AC adapters. The SI3402-A-GMR supports this application by providing Class 3 (up to 17 W) power budget, with the post-regulator delivering 12 V or 5 V to the AP's RF front-end, baseband processor, and Ethernet PHY. According to Skyworks documentation, the device's low-EMI PWM controller with frequency dithering helps AP designs meet FCC Part 15 Class B conducted emissions without complex shielding. The 5x5 mm QFN package occupies minimal board area - critical for ceiling AP enclosure constraints.
Được đề xuất
Network Routers and Switches (PD side)
Small-form-factor network routers and switch peripherals that receive PoE power use the SI3402-A-GMR to convert the 48 V Ethernet line input into a regulated logic supply. The Si3402-A handles both isolated flyback (for SELV compliance) and non-isolated buck configurations, allowing the design to choose isolation based on whether the router has an RJ-45 port serving end users vs. an interior connection. According to the Skyworks datasheet, the integrated diode bridges and hot-swap controller reduce external BOM from 25+ discrete components to fewer than 10, enabling compact router PCB layouts. The 17 W capability supports Class 3 router and small switch designs.
Được đề xuất
Security Cameras and Network Surveillance
Outdoor PoE security cameras receive both data and 13 W to 17 W of power over a single Cat5e/Cat6 cable, using the SI3402-A-GMR to manage the 48 V line input and deliver a clean 12 V or 5 V rail to the image sensor, ISP, and PTZ motors. The Si3402-A's integrated hot-swap FET with inrush current limiting (programmable via HOT-RES) protects the camera's bulk input capacitor at hot-plug events - critical when cameras are reconnected after maintenance. According to Skyworks documentation, the device's -40 C to +85 C operating range tolerates outdoor enclosure thermal stress, and the auto-MPS function keeps the camera online during momentary line drops.
Được đề xuất
IoT and Smart Building Sensors
PoE-powered IoT endpoints such as smart building sensors, HVAC controllers, and smart lighting nodes use the SI3402-A-GMR to harvest up to 13 W from a building's structured Ethernet cabling. The Si3402-A's compact 5x5 mm QFN-20 package fits within the small form-factor sensor enclosures typical of building automation, and the low-EMI PWM signature helps the device coexist with RF sub-GHz or BLE radios in the same product. According to the Skyworks EVB documentation, the design scales down to sub-1 W non-isolated buck topologies for sensors, reducing BOM cost vs. each having its own AC adapter.
Được đề xuất
Low-Power LED Lighting Controllers
Connected LED lighting fixtures in office and industrial spaces use PoE power for both data (lighting control) and supply (the LED driver). The SI3402-A-GMR provides the PD interface and isolates or non-isolates the LED driver topology, with the device's 17 W budget supporting a single LED node or a small array. According to the Skyworks datasheet, the part's frequency-dithered PWM signature reduces EMI that could otherwise interact with nearby lighting control wireless systems. The integrated hot-swap controller handles the large LED bulk capacitors without overcurrent faults at plug-in.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho SI3402-A-GMR — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | SI3402-B-GMR | SI3402-A-GM | Si3402-B-GM | Si3402 (base, no suffix) |
|---|---|---|---|---|---|
| Brand | Skyworks Solutions, Inc. (formerly Silicon Labs) | Skyworks Solutions, Inc. | Skyworks Solutions, Inc. | Skyworks Solutions, Inc. | Skyworks Solutions, Inc. (Silicon Labs) |
| Package | 20-QFN (5x5 mm) with Exposed Pad | 20-QFN (5x5 mm) - same | 20-QFN (5x5 mm) - same | 20-QFN (5x5 mm) - same | 20-QFN (5x5 mm) - same |
| Maximum Output Power | 17 W (Class 3) | 17 W (Class 3) | 17 W (Class 3) | 17 W (Class 3) | 17 W (Class 3) |
| Standards Compliance | IEEE 802.3af + pre-standard PoE | IEEE 802.3af + pre-standard PoE | IEEE 802.3af + pre-standard PoE | IEEE 802.3af + pre-standard PoE | IEEE 802.3af + pre-standard PoE |
| Lifecycle Status | Last-Time-Buy / End-of-Life | Active | Last-Time-Buy | Active | Discontinued |
| On-Chip Diode Bridges | Yes (both data and spare pairs) | Yes (both pairs) | Yes (both pairs) | Yes (both pairs) | Yes (both pairs) |
| On-Chip Hot-Swap FET Rating | 100 V | 100 V | 100 V | 100 V | 100 V |
| Operating Temperature Range | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Packaging Format | Tape & Reel (TR) - 2500 pcs | Tape & Reel (TR) | Tray (GM suffix) | Tray (GM suffix) | Varies by order |
Bảo phân biệt quan trọng
- Only pin-compatible Si3402 family upgrade with active lifecycle status (vsSi3402-A-GM)
- Pre-Standard (legacy/Cisco) PoE support for non-802.3af legacy switches (vsTI TPS2378)
- Single-chip 802.3af solution reduces BOM vs. discrete PSE bridge + hot-swap (vsSi3402-B-GM)
Ghi chú thiết kế
Estimated: the Si3402-A PoE hot-swap front end operates between 37 V and 57 V, so the PCB layout around the VPORTP/VPORTN/VRET inputs must use a minimum 4 mil (0.1 mm) trace-to-trace clearance per IPC-2221 and place a 100 V-rated ceramic capacitor (e.g., 0.1 uF X7R 100 V) within 2 mm of the VPORT pins. Per the Skyworks datasheet section 7, do not run low-voltage digital traces under the line-side rectifier area to avoid noise coupling into the feedback loop.
At 17 W output with 90% efficiency, the Si3402 + external MOSFET lose roughly 1.5 W to 2 W. Estimated: assuming theta_JA of 40 C/W on a 1 square inch top-layer copper pour, junction temperature rise above ambient is 60-80 C. The exposed thermal pad MUST be soldered to a continuous ground plane that spans at least 100 mm^2 area; per datasheet section 8, multiple thermal vias under the EP are required for designs derating >3 W of internal dissipation.
Three common pitfalls with the SI3402-A: (1) Forgetting to populate the RT resistor (oscillator fails to start, no output voltage); (2) Using standard 0805 capacitors on VPORT instead of 100 V-rated parts - these will arc over at 57 V line events; (3) Omitting the inrush current-limiting resistor at HOT-RES leads to the upstream PSE tripping its current limit at plug-in. The device DOES NOT include internal short-circuit protection on the post-regulator output - add a fuse or PTC in the secondary loop.
The Si3402-A's PWM controller uses ~250 kHz switching frequency; to meet EN 55022 Class B conducted emissions, add a pi-filter (10 uF + 1 uH + 10 uF) on the output. According to the Skyworks EVB schematic, the input common-mode choke and Y-cap safety capacitor across the isolation barrier are required to meet both conducted and radiated emissions; consult the EVB layout for guard-trace routing around the line-side bridge.
Thông tin tuân thủ
RoHS compliant per Skyworks product page. Not AEC-Q100 qualified - the SI3402 is intended for commercial/industrial PoE PD applications, not automotive. Halogen-free status not explicitly stated in the verified data.
