SI3402-A-GM - 17W PoE PD Controller, 802.3af | Skyworks
MPN: SI3402-A-GM ⚠ Lần mua cuốiSI3402-A-GM Tóm tắt
A PoE PD controller is the front-end IC in an IEEE 802.3af/at powered device that accepts the 44-57 V DC voltage delivered over the spare or data pairs of a 10/100/1000BASE-T Ethernet cable and converts it to a regulated low-voltage rail (typically 3.3 V, 5 V, or 12 V) for downstream circuitry. Within the power management IC hierarchy, the Si3402 sits at the interface between the PoE PHY front-end and the host DC-DC conversion stage, replacing dozens of discrete components with one IC plus a small magnetic output inductor and input capacitor bank.
Key features include 802.3af Type 1 (Class 3) signature compliance, integrated diode bridges on the Ethernet pairs, an internal hot-swap FET with inrush current limiting, a 100 V abs-max transient-tolerant input stage, low-EMI PWM switching with frequency dithering, and an auxiliary supply support input (SP1/SP2). The 20-QFN package offers a low-profile 5x5 mm footprint with thermal pad, suitable for compact IoT and IP-terminal designs.
The Si3402 architecture combines detection, classification, isolation hand-shake, and synchronous rectification in a single die. The internal hot-swap MOSFET eliminates the external pass device, and the integrated bridges remove the need for four discrete diodes. This minimizes BOM count, PCB area, and overall system cost while maintaining >85% end-to-end conversion efficiency.
Typical applications include VoIP phones, wireless access points, IP cameras, IoT gateways, industrial sensors, and small-form-factor Ethernet-powered appliances. The device also fits point-of-sale terminals and security access controllers where single-cable power-and-data is desirable. Compared to TI's TPS2375 and Maxim's MAX5960, the Si3402's integrated bridges reduce BOM by approximately 15 components.
When designing with this part, ensure the RJ45 connector's center-tap or signal-pair routing matches the CT1/CT2 or SP1/SP2 pins per the EVB reference design, and provide adequate thermal copper on the EP pad. Note that the SI3402-A revision is end-of-life - the pin-compatible Si3402-B-GMR is the recommended successor.
This page synthesizes distributor pricing, A/B-revision comparison, and practical PoE layout guidance not found in the manufacturer datasheet alone.
Bộ thay thế dễ dàng lắp đặt cho SI3402-A-GM — 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-GM (cùng hình factor và footprint) — khác nhau ở Maximum Output Power, Package, Product Type, Operating Temperature, Input Voltage Range (PoE).
SI3402-B-GMR
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →SI3402-B-GM
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →SI3404-A-GMR
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
SI3402-A-GM Tỷ lệ tối đa & tính chất điện
| Product Type | PoE Powered Device (PD) Controller with integrated switching regulator |
| PoE Standard | IEEE 802.3af (Type 1, Class 3) |
| Maximum Output Power | 17 W |
| Input Voltage Range (PoE) | 37 V to 57 V DC |
| Input Voltage Transient Tolerance | 100 V absolute max |
| Điện áp đầu ra | Adjustable (typical 3.3 V, 5 V, 12 V via external components) |
| Switching Topology | Synchronous buck PWM with low-EMI frequency dithering |
| Integrated Diode Bridges | Yes (on-chip) |
| Integrated Hot-Swap FET | Yes (internal pass device) |
| Number of Channels | 1 |
| Nhiệt độ hoạt động | -40 C to +85 C |
| Hộp | 20-QFN (5x5 mm) with exposed pad |
| Kiểu lắp đặt | Surface Mount |
| Cấp MSL | 2 |
| Trạng thái RoHS | Compliant |
Cấu hình chân SI3402-A-GM
| Chân 1 | CT1 — Center-tap 1, positive Ethernet pair input |
| Chân 2 | CT2 — Center-tap 2, negative Ethernet pair input |
| Chân 3 | AGND — Analog ground |
| Chân 4 | SP1 — Spare-pair 1 input |
| Chân 5 | SP2 — Spare-pair 2 input |
| Chân 6 | PGND — Power ground |
| Chân 7 | VCC — Internal supply decoupling |
| Chân 8 | CLASS — Power classification setting resistor |
| Chân 9 | DET — Detection signature resistor |
| Chân 10 | FB — Feedback for output voltage regulation |
| Chân 11 | COMP — Compensation network node |
| Chân 12 | SS — Soft-start programming |
| Chân 13 | AUX — Auxiliary supply support input |
| Chân 14 | RT — Switching frequency setting resistor |
| Chân 15 | SW — Buck switch node |
| Chân 16 | SW — Buck switch node |
| Chân 17 | BST — Bootstrap for high-side gate drive |
| Chân 18 | VDD — Gate driver supply |
| Chân 19 | NC — Not connected (per datasheet) |
| Chân 20 | NC — Not connected (per datasheet) |
Ứng dụng tiêu biểu
SI3402-A-GM phù hợp cho 6 Áp dụngs: VoIP Phones and Unified Communications, Wireless Access Points, IP Cameras and Surveillance, Industrial IoT Gateways and Sensors, Point-of-Sale Terminals, Security Access Controllers.
VoIP Phones and Unified Communications
The SI3402-A-GM's 17 W Class 3 PoE capability and integrated diode bridges make it ideal for VoIP phone mainboards where PCB area is at a premium. Typical designs use the IC to deliver 5 V at 2-3 A to the audio codec, display backlight driver, and Ethernet switch. Its low-EMI PWM with frequency dithering eliminates audible noise in the handset receiver, and the on-chip hot-swap FET handles 802.3af inrush without an external pass device.
Được đề xuất
Wireless Access Points
Wi-Fi access points and small business APs benefit from the SI3402-A-GM's single-cable power-and-data simplicity. The device accepts 37-57 V PoE input and produces 3.3 V or 5 V rails for the Wi-Fi SoC, PA, and LEDs. Its integrated bridges remove the need for discrete rectification, allowing compact AP designs where the Ethernet jack and PoE controller occupy less than 200 mm² of board space. End-to-end efficiency above 85% keeps thermal rise manageable in sealed enclosures.
Được đề xuất
IP Cameras and Surveillance
Indoor IP cameras using the SI3402-A-GM can deliver 5 V or 12 V output for the image sensor, SoC, and IR LED illuminator array. The 17 W Class 3 budget covers 4 MP cameras with 5-10 m IR illumination. The integrated bridges and low-EMI switching minimize conducted emissions that could couple into the image sensor's analog front-end, preserving image SNR. The 5x5 mm QFN package fits compact dome-camera PCBs where vertical clearance is constrained to 2 mm.
Được đề xuất
Industrial IoT Gateways and Sensors
Industrial IoT gateways deployed in factory floors and remote sites benefit from PoE single-cable deployment via the SI3402-A-GM. The device's 100 V transient tolerance survives cable discharge events common in industrial wiring, and the -40 to +85 C operating range covers most outdoor cabinet environments. Typical designs step down 48 V PoE to 12 V for sensor analog front-ends and 3.3 V for the IoT gateway SoC, eliminating separate power wiring in plant retrofits.
Được đề xuất
Point-of-Sale Terminals
Retail point-of-sale (POS) terminals increasingly use PoE to consolidate power, network, and payment-data cabling. The SI3402-A-GM's 17 W output supports a 7-inch touchscreen, thermal printer, and mag-stripe reader from a single Ethernet cable. Its low-EMI design avoids interference with the NFC contactless-payment antenna, which is sensitive to switching regulator harmonics in the 13.56 MHz band. The integrated bridges reduce BOM cost, critical for price-sensitive POS deployments.
Được đề xuất
Security Access Controllers
Door access controllers, badge readers, and intercom stations benefit from the SI3402-A-GM's compact 20-QFN footprint and integrated bridge design. A single PoE cable delivers 12 V or 5 V for the keypad, RFID reader, magnetic-lock relay, and display. The 17 W budget supports inductive-lock activation peaks while the hot-swap controller manages cable insertion surges without affecting downstream logic. The exposed pad enables efficient thermal dissipation in metal-enclosed door stations.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho SI3402-A-GM — 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-B-GM | SI3404-A-GMR |
|---|---|---|---|---|
| Brand | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions |
| Package | 20-QFN (5x5) | 20-QFN (5x5) - same | 20-QFN (5x5) - same | 20-QFN (5x5) - same |
| Maximum Output Power | 17 W | 17 W (same) | 17 W (same) | 30 W (802.3at Type 2 capable) |
| PoE Standard | IEEE 802.3af (Type 1) | IEEE 802.3af (Type 1) - same | IEEE 802.3af (Type 1) - same | IEEE 802.3af/at (Type 1+2) |
| Integrated Diode Bridges | Yes (on-chip) | Yes (same) | Yes (same) | Yes (same) |
| Lifecycle Status | Last-Time-Buy | Active | Active | Active |
| Pin Compatibility | - | Drop-in compatible | Drop-in compatible | Drop-in compatible (same package) |
| Recommended Use | Existing designs only | All new designs | All new designs | Higher-power PoE+ designs |
Bảo phân biệt quan trọng
- Integrated diode bridges on-chip (vsTPS2375 (Texas Instruments))
- Pin-compatible Si3402-B successor available (vsDiscontinued TI PD controllers)
- Class 3 17 W output with internal hot-swap (vsMAX5960 (Maxim/ADI))
Ghi chú thiết kế
At 17 W output and 48 V PoE input, the Si3402 dissipates approximately 2-3 W internally. The 20-QFN exposed pad MUST be soldered to a copper pour of at least 1 square inch (645 mm²) on top and inner PCB layers, connected via an array of 0.3 mm thermal vias to maximize heat extraction. Estimated: theta_JA drops from approximately 50 C/W (no thermal pad) to 30 C/W with proper EP soldering. Junction temperature should stay below 110 C in worst-case conditions.
Place the input bulk capacitor (typically 47 uF / 100 V) within 3 mm of the CT1/CT2 and SP1/SP2 pins to minimize hot-swap loop inductance. The buck switch node (SW) trace must be short and wide (>= 0.8 mm) to limit dv/dt-induced EMI. Route the feedback (FB) trace away from the SW node by at least 3 mm to avoid noise coupling into the output-voltage regulation loop.
Do not power the Si3402 from an auxiliary supply above 16 V - the AUX input is rated to that maximum and exceeding it damages the internal hot-swap logic. When migrating from Si3402-A to Si3402-B, verify that the output inductor, feedback resistor divider, and soft-start capacitor values still meet Si3402-B startup timing per the EVB reference schematic; some BOM changes are required, although the IC is pin-compatible.
The Si3402 incorporates frequency-dithered PWM to spread switching harmonics and meet FCC Class B conducted emissions without external filtering. For sensitive applications (e.g. NFC-equipped POS terminals, AM-band radio), add a small ferrite bead on the PoE input pair near the RJ45 connector to attenuate common-mode emissions above 30 MHz.
Thông tin tuân thủ
RoHS compliant per Skyworks product page. Not AEC-Q100 qualified (commercial/industrial grade PoE controller). Last-Time-Buy status per Skyworks product migration notice; recommended successor is Si3402-B-GMR.
