The reference design contains a motherboard with RJ-45 connectors, DIMM-format playing cards, and twin working modes for environment friendly Ethernet gadget powering.

Ethernet is standardized underneath IEEE 802.3, whereas Energy over Ethernet (PoE/PoE+) follows IEEE 802.3af/at requirements. The commonest Ethernet community varieties are 10BASE-T (10MHz), 100BASE-TX (100MHz), and 1000BASE-T (1GHz), all utilizing Class 5 (CAT-5) cables. These cables have 4 pairs of wires (eight wires complete, organized as pairs 1-2, 3-6, 4-5, and 7-8). In 10/100MHz Ethernet, solely two pairs (1-2 and 3-6) are used for knowledge transmission, whereas 1GHz Ethernet makes use of all 4 pairs.

The reference design of PoE by Analog gadgets contains a motherboard and as much as 5 DIMM 3.3V-format PC boards. The motherboard is supplied with 5 168-pin DIMM-style connectors, RJ-45 connectors/magnetics for 32 Ethernet ports, a ±50V remoted RS-232 transceiver (MAX3250), and a SPI-to-USB controller (MAX3420).

There are three forms of DIMM-format playing cards on this design. The grasp card options an MAXQ2000 microcontroller, an MAX5020 DC-DC converter to generate +3.3V output from -48V enter, and 6 community energy controllers to energy 24 channels. The microcontroller communicates with the MAX5945s, that are situated both on the grasp card itself or on extra slave playing cards, utilizing I²C.

The slave card has six community energy controllers to energy 24 channels. Moreover, there’s a slave B card that holds 4 community energy controllers to energy 16 channels. The reference design can function in stand-alone mode or with a system-level microcontroller.

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Within the mode with a system-level microcontroller, the user-supplied system processor can both configure settings by I²C or enable the microcontroller to make use of built-in defaults. The firmware allows the microcontroller to regulate as much as 16 community energy controllers on every of the three I²C buses, totalling 48 controllers. The system processor determines which occasions to report, permitting the designer to have various ranges of management over the system. Settings are retained in nonvolatile reminiscence, and a packet-based error-detecting protocol ensures knowledge integrity by retransmission if obligatory.

In stand-alone mode, the MAXQ2000 and its firmware independently handle the operation of the MAX5945s. A PC can set parameters, save them within the microcontroller’s nonvolatile reminiscence, question standing, and optionally retrieve saved logs. Communication between the PC and microcontroller happens by way of an RS-232 interface or USB.

The design can accommodate 1 to 48 quad controllers, equating to 4 to 192 ports. The firmware robotically detects and configures the variety of ports, assuming every MAX5945 has a singular I²C tackle.

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Analog Units has examined this reference design, which comes with a Invoice of Materials (BOM), schematics, and different knowledge. The corporate’s web site has extra knowledge concerning the reference design. To learn extra about this reference design, click on right here.