Electronic Design

PoE Modules And Controller Chips Comply With IEEE 802.3af Standard

Coupled with an external power-over-Ethernet (PoE) isolation transformer, the PTB48540 module from Texas Instruments delivers up to 10 W at 3.3, 5, or 12 V. This plug-in power module fully complies with IEEE 802.3af, suiting IP phone consoles, security systems, card readers, point-of-sale terminals, and other Ethernet-powered devices.

Each module incorporates a dc-dc converter. Internal input diode bridges support both data-line and spare-line pair standard Ethernet connections. An input transient suppressor and an electromagnetic-interference filter provide additional protection. With the module's "Output Inhibit" control, the output voltage can be turned off to support an idle condition or power-saving mode. Other features include input undervoltage lockout (UVLO), overcurrent and short-circuit protection, output voltage adjust/trim, and overtemperature protection.

The 41- by 38- by 8.5-mm module is built around one version of TI's latest PoE controller chip, the TPS2375. Three versions of the controller chip are available for designers who want to roll their own PoE supplies. The TPS2375 has 802.3af-compliant UVLO limits. The TPS2377 supports legacy UVLO limits. The TPS2376 has a programmable UVLO via a dedicated input pin. In addition to the basic functions of detection and classification, these controllers include an adjustable inrush limiting feature.

The PTB48540 comes in a 13-pin, double-sided, through-hole or surface-mount package. The TPS2375 is packaged in an eight-pin SOIC or TSSOP. Pricing is $26 for the complete module and $1.25 for the chip, both in 1000-unit lots.

Texas Instruments
(972) 644-5580

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