Two PoE PD families reduce system cost for IoT development

Two Power over Ethernet (PoE) Powered Device (PD) families from Silicon Labs are claimed to deliver best-in-class integration and efficiency for a range of IoT applications.

Silicon Labs’ Si3406x and Si3404 families include all necessary high-voltage discrete components on a single PD chip, says the company. The PD ICs support IEEE 802.3 at PoE+ power capabilities, flexible power conversion options exceeding 90 per cent efficiency, robust sleep/wake/LED support modes and EMI immunity. According to Silicon Labs, these capabilities combine to help developers reduce system cost and time to market for high-power, high-efficiency PoE PD applications.

The rapid expansion of the IoT is boosting demand for PoE+ connectivity in IP cameras, smart lighting luminaires, feature-rich video IP phones, advanced 802.11 wireless access points and smart home appliances. These applications require higher wattage driving increased demand for PD devices that support the PoE+ standard. For example, the latest motor-positioned IP cameras with pan/tilt/zoom and heater elements create heavy loads on power supplies. PoE+ technology brings 30W to support these demanding tasks. Silicon Labs’ Si3406x’s PD interface is for new classes of PoE+-enabled IoT products in residential, commercial and industrial environments.

The Si3406x ICs integrate all power management and control functions required for a PoE+ PD application, converting the high voltage supplied over a 10/100/1000BASE-T Ethernet connection to a regulated, low-voltage output supply. The optimised architecture minimises PCB footprint and external bill of materials cost with the use of economical external components.

Complementing the Si3406x family, the Si3404 IC offers cost-effective, 802.3 Type 1 compliant support for lower power 15W PoE PD applications. The Si3404 includes all interface and control functions required for low power PD applications in a very small footprint.

The Si3406x ICs integrate diode bridges and a transient surge suppressor, enabling direct connection to an Ethernet RJ-45 connector. The regulator’s switching frequency is tunable with a simple external resistor value to avoid unwanted harmonics. An integrated synchronous driver can control a secondary side field effect transistor (FET) to improve power conversion efficiency. Connection to a PSE switch is maintained during sleep mode by an automated maintain-power-signature (MPS) feature.

The Si3406x family’s current-mode-controlled switching regulator supports multiple isolated and non-isolated power supply topologies. The regulator is complemented by an integrated power switching FET.

Samples and production quantities of the Si3406x ICs are available now in low-profile, 5.0 x 5.0mm QFN packages. The Si3404 device is available now in a low-profile, 4.0 x 4.0mm QFN package.


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