DC2579A Analog Devices

DEMO MANUAL DC2579A LTC4279 Single Port UltraPWR PSE Controller Description Demonstration Circuit 2579A features the LTC 4279, setting the LTC4279 LEGACY pin, DUALPD pin and MID an autonomous single port power sourcing equipment pin. A pushbutton switch resets the LTC4279. LEDs indi- (PSE) controller, configured in its UltraPWR mode. cate main supply power and output power are up. Data-In UltraPWR mode aggressively turns on and powers RJ45 connects to a PHY data source and Data-and-Power- custom high power PDs requiring high inrush and/or Out RJ45 connects to a custom high power PD. operationalcurrents. Design files for this circuit board are available at The DC2579A requires a single power supply and pro- DEMO MANUAL DC2579A Quick s tart p D Demonstration circuit 2579A is easy to setup for evaluat- Table 1. Power Supply Range ing the performance of the LTC4279. Refer to Figure 1 for SELV Required MAIN PS Range proper measurement equipment setup, Table 1 for supply Yes 55V 60V settings, and follow the procedure below. No 55V 65V 1. Select HI at LEGACY jumper JP3 to enable LEGACY 6. Connect test measurement probes across DATA1+ mode or select LO to disable LEGACY mode. to DATA1, and DATA2+ to DATA2 for port output 2. Select HI at DUALPD jumper JP2 to enable DUALPD measurements. mode or select LO to disable DUALPD mode. 7. Connect a custom high power PD with a Cat5E Ethernet 3. Select HI at MID jumper JP1 to enable midspan mode cable to RJ45 connector J1. PORT PWR LED2 will turn or select LO to disable midspan mode. on if the port power is on. 4. Connect a power supply with the positive to AGND (J3) 8. Connect a 10BASE-T, 100BASE-T or 1000BASE-T and negative to VEE (J4). PHY data source with an Ethernet cable to J2 for data testing (optional). 5. Ramp up the supply to within the range specified in Table 1 for the configured mode. VEE LED1 will turn Note: Any change in the jumper selections while power is on when the board is powered. on will require a power cycle or pushbutton reset for the change to take effect. o Power Control Certain existing very high power PDs proprietary to the PD manufactures benefit from the UltraPWR mode of the The primary function of the LTC4279 is to control the LT4279. The LTC4279 in UltraPWR mode simply provides delivery of power to the PSE port. It does this by control- very high power to these proprietary PDs. ling the gate drive voltage of an external power MOSFET (Q1) while monitoring the current via an external sense Figure 12 (UltraPWR Power vs V ) in the LTC4279 data PSE resistor (RS1) and the output voltage at the OUT pin. sheet shows PSE source power (at the PSE RJ45 jack) This circuitry serves to couple the raw VEE input supply and PD delivered power (at the PD RJ45 jack) vs V . PSE to the port in a controlled manner that satisfies the PDs The gray shaded area above 60V shows voltages exceed- power needs while minimizing both power dissipation ing SELV maximum systems exceeding SELV maximum in the MOSFET and disturbances on the VEE backplane. voltage may incur additional regulatory hurdles. UltraPWR Mode Data In/Data And Power Out The LTC4279 is configured for UltraPWR mode by a 13.0k The DC2579A can be set up in a midspan PSE configura- resistor (RPM1) from the PWRMODE pin to VEE. Unlike tion for data and power evaluation. A PD is connected with LTPoE++ and the IEEE 802.3at standard, UltraPWR is not a a Cat5e cable to DATA AND POWER OUT RJ45 connector system defined standard. A PSE in UltraPWR mode issues (J1). Power is injected on to the Ethernet lines through the up to three class events and powers valid detected PDs center taps of the 1000BASE-T Ethernet transformer (T1). with maximum deliverable power, as determined by the A 10BASE-T, 100BASE-T or 1000BASE-T PHY data source PSE output voltage, V . Warning: UltraPWR mode is is connected with an Ethernet cable to DATA IN RJ45 con- PSE not IEEE compliant. nector J2 for optional data testing. Data is passed from J2 to J1 along with the injected power. dc2579af 2 peration ure roce