DC1567B

DC1567B demonstration circuit features the LTC4274, a single power sourcing equipment (PSE) controller designed for use in IEEE 802.3 Type 1 and Type 2 (high power) compliant Power over Ethernet (PoE) systems. The LTC4274 is configured in the DC1567B as a midspan power injector where data comes in from an existing network system and out, along with power, to a powered device (PD). The LTC4274 autonomously detects and classifies a PD, turns power on to the port, and disconnects port power without the need for a MCU. A two second backoff timer supports the midspan configuration. A 55V nominal supply is recommended to power the demo board. A simple regulator circuit on the board powers the digital supply of the LTC4274. The LTC4274 delivers low heat dissipation by utilizing a low RON external MOSFET and a 0.25ohm sense resistor, eliminating the need for expensive heat sinks. An external MOSFET also provide a more robust solution compared to an integrated MOSFET.

• LTC4274-controlled power connects to centre taps of Ethernet transformers for data pairs 4/5 and 7/8
• Integrated RJ45 includes Ethernet transformer, common mode termination, and LEDs
• One LED is also controlled by the LTC4274 to indicate the port is powered
• Test turrets provide test points for port power measurements
• DC1567B has increased surge protection from the DC1567A
• DC1567B is Ethernet Alliance™ certified
• Input voltage of 51V to 57V at (GND – VEE, typ voltage, IEEE Type 1 and Type 2 compliant output)
• VDD supply voltage range from 3.4V to 3.8V at VDD – DGND, generated on demo board from VEETA = 25°C
• 2.5s midspan backoff at MID pin logic high, backoff time after detection
• 4-point PD detection at 25K signature detection and 2-event classification at class 4