Si3402-C FULLY-INTEGRATED IEEE 802.3-COMPLIANT POE PD INTERFACE AND LOW-EMI SWITCHING REGULATOR Features Pin-compatible replacement for the Incorporates switcher EMI- obsolete Si3402-A reduction techniques. IEEE 802.3 standard-compliant Supports non-isolated and isolated solution, including pre-standard switching topologies (legacy) PoE support Comprehensive protection circuitry Highly-integrated IC enables Transient overvoltage protection compact solution footprints Undervoltage lockout Minimal external components Thermal shutdown protection Ordering Information: Integrated diode bridges and Foldback current limiting transient surge suppressor Allows external Schottky diode See page 18. Integrated switching regulator bypass of integrated diode bridges controller with on-chip power FET without requiring CT/SP pin Integrated dual current-limited connection Pin Assignments hotswap switch Low-profile 5 x 5 mm 20-pin QFN Programmable classification circuit RoHS-compliant 5 x 5 mm QFN (Top View) Applications Voice over IP telephones and Point-of-sale terminals 20 19 18 17 16 15 adapters Internet appliances Wireless access points Network devices 1 EROUT 14 CT1 Security cameras High power applications SSFT* 2 VNEG 13 CT2 (PAD) 3 VDD 12 VPOSF Description ISOSSFT* 4 11 SP1 The Si3402 integrates all power management and control functions required in a 567 89 10 Power-over-Ethernet (PoE) powered device (PD) application. The Si3402 converts the high voltage supplied over the 10/100/1000BASE-T Ethernet connection into a regulated, low-voltage output supply. The optimized Note: Original pin names shown for compatibil- architecture of the Si3402 minimizes the solution footprint, reduces external ity reasons, but SSFT, ISOSSFT, VPOSS, BOM cost, and enables the use of low-cost external components while and VSS1 are not internally connected. maintaining high performance. The Si3402 integrates the required diode bridges and transient surge suppressor, thus enabling direct connection of the IC to the Ethernet RJ-45 connector. The switching power FET and all associated functions are also integrated. The integrated switching regulator supports isolated (flyback) and non-isolated (buck) converter topologies. The Si3402 supports IEEE 802.3 Type 1 (Class 3 and below) Powered Device applications. Standard external resistors connected to the Si3402 provide the proper IEEE 802.3 signatures for the detection function and programming of the requested power class. Startup circuits ensure well-controlled initial operation of both the hotswap switch and the voltage regulator. The Si3402 is available in a low- profile, 20-pin, 5 x 5 mm QFN package. The Si3402-C is a pin-compatible replacement of the obsolete Si3402-A. PCB layouts designed for Si3402-A can be reused with Si3402-C, but some component value changes are required. The Si3402-Cs functionality is similar to that of the Si3402-B but without the requirement to make a connection between the Ethernet jack and CT1, CT2, SP1, or SP2 pins when bypassing the integrated diode bridge with external Schottky diodes. Further, PLOSS functionality is removed from the Si3402-C. Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com Rev. 1.0 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice August 6, 2021 NC FB RDET VSS2 HSO SWO RCL VSS1 VNEG VPOSS SP2 VSSASi3402-C Functional Block Diagram VPOSF VPOSS* RDET RCL SSFT* VDD ISO SSFT * Detection PW M Control EROUT & and EM I CT1 FB Classification Hotswap Lim iting Control CT2 & Comm on SP1 Hotswap Bias Switch S w itching SP2 SW O & FET C urrent lim it VNEG HSO PLOSS VSSA VSS1* VSS2 Note: Original pin nam es shown for com patibility reasons, but SSFT, ISOSSFT, VPO SS, and VSS1 are not internally connected. 2 Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com Rev. 1.0 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice August 6, 2021 Rectification & Protection