SI3402-A-GM - 17W PoE PD Controller, 802.3af | Skyworks
N.º de pieza: SI3402-A-GM ⚠ Última compra| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $2.85 | $2,85 |
| 10 | $2.65 | $26,50 |
| 100 | $2.4 | $240,00 |
| 500 | $2.15 | $1.075,00 |
| 1.000 | $1.92 | $1.920,00 |
SI3402-A-GM Descripción general
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.
Alternativas directas para SI3402-A-GM — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con SI3402-A-GM (mismo factor de forma y huella) — difiere en Maximum Output Power, Package, Product Type, Operating Temperature, Input Voltage Range (PoE).
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
SI3402-B-GMR
✅ Sustitución directa✓ En stock
$2.15 / unidad
Ver hoja de datos →SI3402-B-GM
✅ Sustitución directa✓ En stock
$2.45 / unidad
Ver hoja de datos →SI3404-A-GMR
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
SI3402-A-GM Valores máximos y características eléctricas
| 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 |
| Tensión de salida | 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 |
| Temperatura de funcionamiento | -40 C to +85 C |
| Encapsulado | 20-QFN (5x5 mm) with exposed pad |
| Tipo de montaje | Surface Mount |
| Nivel MSL | 2 |
| Estado RoHS | Compliant |
Configuración de pines de SI3402-A-GM
| Pin 1 | CT1 — Center-tap 1, positive Ethernet pair input |
| Pin 2 | CT2 — Center-tap 2, negative Ethernet pair input |
| Pin 3 | AGND — Analog ground |
| Pin 4 | SP1 — Spare-pair 1 input |
| Pin 5 | SP2 — Spare-pair 2 input |
| Pin 6 | PGND — Power ground |
| Pin 7 | VCC — Internal supply decoupling |
| Pin 8 | CLASS — Power classification setting resistor |
| Pin 9 | DET — Detection signature resistor |
| Pin 10 | FB — Feedback for output voltage regulation |
| Pin 11 | COMP — Compensation network node |
| Pin 12 | SS — Soft-start programming |
| Pin 13 | AUX — Auxiliary supply support input |
| Pin 14 | RT — Switching frequency setting resistor |
| Pin 15 | SW — Buck switch node |
| Pin 16 | SW — Buck switch node |
| Pin 17 | BST — Bootstrap for high-side gate drive |
| Pin 18 | VDD — Gate driver supply |
| Pin 19 | NC — Not connected (per datasheet) |
| Pin 20 | NC — Not connected (per datasheet) |
Aplicaciones típicas
SI3402-A-GM es adecuado para 6 aplicacións: 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.
Recomendado
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.
Recomendado
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.
Recomendado
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.
Recomendado
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.
Recomendado
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.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para SI3402-A-GM — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | 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 |
Diferenciadores clave
- Integrated diode bridges on-chip (frente a TPS2375 (Texas Instruments))
- Pin-compatible Si3402-B successor available (frente a Discontinued TI PD controllers)
- Class 3 17 W output with internal hot-swap (frente a MAX5960 (Maxim/ADI))
Notas de diseño
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.
Información de cumplimiento
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.
