AND8333/D High Power PoE Applications

Transcription

1 /D High Pwer PE Applicatins 1.0 Scpe This applicatin nte explains hw the NCP1081 PE-PD device can be used t deliver high pwer levels t applicatins ver the Ethernet cable. Sufficient infrmatin is included t create cmplete end-t-end slutins with high pwer PE-PSE equipment available n the market. An verview f different ptins and cnfiguratins is prvided. 2.0 High Pwer Equipment 2.1 High Pwer PSE Equipment: Midspans and Pwer Injectrs The IEEE802.3af standard supprts up t 13W f pwer distributed ver the Ethernet cable. The IEEE802.3at (Draft 3.0) standard supprts pwer levels up t 25.5W. Bth standards describe pwer distributin ver tw pairs frm the fur pairs f the Ethernet cable as shwn in Figure 1. PSE PD UTP 48V Pwer Surcing Equipment (PSE) Pwered Device (PD) DC supply generatin Pwer Surcing: Line (100m): Pwered Device: IEEE 802.3af Vut af = V Pmin af = 15.4 W Rmax cat5 = 20 Ohms Vdrp = 7 V Icable=350mA Vut af = V Pmax af = W IEEE 802.3at Vut at = V Pmin at = 30 W Rmax cat6 = 12.5 Ohms Vdrp = 9 V Icable=600mA Vut at = V Pmax at = 25.5 W Figure 1: IEEE Standard Pwer Distributin Over Tw Pairs 2008 SCILLC. All rights reserved. Publicatin Order Number: April 2008 Rev. 2 AND8333/D

2 The higher pwer level fr the IEEE802.3at standard is accmplished by raising the minimum IEEE803.3af standard vltage n the cable frm 44V t 50V. CAT5e/6 cable is prpsed fr high pwer applicatins due t lwer resistance. The pwer level in IEEE802.3at is increased frm 13W t 25.5W by als changing the maximum cable current frm 350mA t 720mA. Nte that the 25.5W pwer budget is nt fully available fr the PD lad due t lsses which ccur in the PD circuit between the Ethernet input jack and the vltage regulatr utput. Pwer lsses ccur in the DC-DC cnverter blck, in the input dide bridge and als in the PE-PD device. An verall efficiency f 85 percent is realistic. This results in an applicatin pwer budget f 11W fr IEEE802.3af and 20.4W fr IEEE802.3at. Table 1: Pwer Budget Levels IEEE 802.3af IEEE 802.3at Optin A Optin B Optin C Optin D Cable (length 100m) Cat 3 Cat 5e Cat 5e Cat 5e Cat 5e Cat 5e Pairs used Cable resistance (Ohm) Max. current per pair (ma) Vltage by PSE (V) Pwer by PSE (W) Max. cable pwer lss (W) Input pwer PD (W) Efficiency f PD+ cnverter 85% 85% 85% 85% 85% 85% Output pwer PD (W) Overall efficiency 71% 70% 71% 64% 75% 71% Sme PE applicatins require mre pwer than the 25.5W pssible with the IEEE802.3at (Draft 3.0) standard which limits the current t 600mA. The mean reasn fr this limit is t reduce the generatin f heat when a large number f Ethernet cables are bundled. Frtunately, it is pssible t achieve higher pwer levels with prprietary cnfiguratins. Optin A achieves higher pwer levels by increasing the minimum vltage level t 56V and the current up t 720mA. Optin B cmbines raising the vltage t 56V and the current t 1100mA ver tw pairs. Optin C delivers mre utput pwer than Optin B but distributed ver fur pairs with a lwer current 520mA per pair. Optin D delivers abut twice the pwer f Optin A by distributing pwer ver fur pairs instead f tw. Figure 2: PE Injectr Midspans are multiprt pwer injectrs placed in series with switches. An injectr is a single prt midspan. Figure 2 gives an verview n hw a single prt midspan (injectr) injects pwer int the Ethernet cable. The pwer is retrieved frm the cable via a splitter bx. The NCP1081 can replace the high pwer splitter bx delivering the required high pwer levels. Rev. 2 Page 2 f 8

3 Table 2 lists high pwer PSE switches, midspans and injectr equipment currently available n the market. Tw- and fur-pair cnfiguratins are available. Phihng Phihng has midspans and injectrs in their prduct line. Phihng has tw-pair cnfiguratins up t 30W and 36W and fur-pair versins up 60W and 80W. The fur-pair cnfiguratins have prprietary detectin and the tw-pair cnfiguratins have Class 4 classificatin. Class 4 classificatin des nt include a Layer 2 handshake since the midspan had n data cmmunicatin channel. One NCP1081 device in cmbinatin with the Phihng tw-pair 36W device can deliver 25W utput pwer t the applicatin with Class 4 classificatin (single-finger IEEE802.3at classificatin). Tw NCP1081 devices in cmbinatin with the Phihng tw-pair Optin C and D apprach can be implemented with fur-pairs t deliver mre than 40W t the applicatin. Krenix Krenix has Ethernet switches with 30W per prt. The equipment uses Class 4 and sme include Layer 2 handshaking. The NCP1081 can nly deliver 20W t the applicatin in cmbinatin with this equipment. Panduit Panduit midspan delivers 30W per prt. Classificatin is via Class 4 withut Layer 2 handshaking. The NCP1081 can nly deliver 20W t the applicatin in cmbinatin with this equipment. Table 2: Overview f High Pwer PSE Equipment Cmpany Type Name Pwer PSE Pwer PD Pwer Prts Pairs Vltage Current Handshake Watt Pwer Output/Prt PD Output Vlt ma/per Pair Phihng Injectr POE20U Class 4 Injectr POE30U Class 4 Injectr POE60U Prprietary 12.5K detectin Injectr POE80U Prprietary 12.5K detectin Midspan POE480U-4UP ?? Prprietary 12.5K detectin Midspan POE480U-8UP ?? Prprietary 12.5K detectin Midspan POE576U-8HP ? 550 Class 4 Midspan POE576U-16HP ? 550 Class 4 Krenix Switch Jetnet Class 4 Layer 2 Switch Jetnet Class 4 Layer 2 Panduit Midspan DPOE ?? Class Handshaking Prtcls The NCP1081 can handle all defined types f handshaking and is cmpatible with all the PSE equipment described abve. The classificatin prcess defined in the high pwer IEEE802.3at standard extends beynd the ne defined in the lw pwer 802.3af standard because it can be dne in several ways. First the classificatin current in the PE-PD must be set t the Class 4. Then the PE-PD can be classified by the IEEE802.3at PSE based n Tw Event Physical Layer classificatin (s called Layer 1), Link Layer classificatin (s called Layer 2) r a cmbinatin f bth. Hwever, high pwer PSE which are nn cmpliant with the previus prcess can als be used with the NCP1081 if they use a prprietary current classificatin. These handshaking prtcls are explained in mre detail in the fllwing paragraphs High Pwer Classificatin: Tw Event Physical Layer Classificatin (Layer 1) This first methd is characterized by a classificatin event being perfrmed twice, meaning the PSE frces the PD t enter in the classificatin range tw times. This is implemented in the hardware f the PSE and PD devices. Interest in this Layer 1 apprach is mainly driven by the need fr basic midspan equipment where it is desirable t avid having t access the data channel stream. Nne f the equipment abve is using this classificatin principle but the standard is evlving in this way fr midspans and injectrs. Rev. 2 Page 3 f 8

4 High Pwer Classificatin: Layer 2 Classificatin A PSE perfrming Layer 2 classificatin classifies the PD in tw phases. In the first phase the PSE perfrms a physical classificatin with ne event (same prcedure used in the IEEE802.3af standard). The classified PD is then pwered up by the PSE under lw pwer cnditins, meaning that the pwer can nt exceed the IEEE802.3af limits. The secnd phase ccurs a very shrt perid after pwerup; the PD will cmmunicate its required pwer level t the PSE via an Ethernet data packet. The IEEE802.3at draft specificatin suggests using the link layer discvery prtcl (LLDP) accrding t the IEEE802.1AB-2005 specificatin that is being rewrked and fllws the messages described in the IEEE802.3at specificatin. The designer will have t implement a LLDP agent, a sftware rutine implementing a state machine that is prviding access t the internal data base f the netwrk device. Nt all f the databases, such as management infrmatin base (MIB) that are cmmnly accessible via LLDP need t be implemented, but fr sure the IEEE802.3at pwer management data sets needs t be implemented High Pwer Classificatin: Prprietary A third methd is prprietary. Since mst midspan equipment des nt currently supprt Layer 1 handshaking, mst f the PSE equipment tday uses a prprietary classificatin, typically using a ne event physical classificatin handshake. Prprietary detectin resistrs are pssible t enable fur-pair cnfiguratins. The Phihng equipment uses a 12.5K Ohm resistr instead f 25K Ohm detectin resistr. Anther ptin is t use a ne event Layer 1 classificatin using Class 4 t enable higher pwer levels withut ding a Layer 2 classificatin. Mst f the equipment abve is using this principle. This principle is actually a single-finger Layer 1 handshake with reserved Class Handshaking Indicatin The nclass_at pin n the NCP1081 indicates t the micrcntrller if a tw event physical classificatin event ccurred. Once it has been detected, the nclass_at pen drain pin ges lw. In all ther cnditins, such as a ne event physical classificatin handshake, the nclass_at pin stays high. Pwered Device Applicatin VDDL VDDL Rbip Csup VSUP Layer 2 Engine 20 ua Rled IN1 nclass_at Opt1 IN2 Micrprcessr r Micrcntrller Class_AT ARTN Features GND NCP1081 Islatin (Islated DC/DC cnverter) Figure 3: nclass_at Pin Cnnecting the NCP1081 t a Phihng midspan keeps the nclass_at pin high. Cnnecting t an IEEE802.3at cmpliant midspan will bring the nclass_at pin lw. Rev. 2 Page 4 f 8

5 3.0 High Pwer Cnfiguratins W r 30W Single Output RJ-45 Rclass VPORTP CLASS VDDH Cvddh Cpd T1 D1 Vutput Pairs Spare Pairs DB1 DB2 Z_line Cline R1 R2 Rinrush Rilim1 INRUSH VDDL ILIM1 NCP1081 nclass_at UVLO GATE TEST2 CS TEST1 FB VPORTN1 ARTN VPORTN2 OSC SS Rsc Css COMP RTN Cvddl LD1 Rd1 Rslpe M1 Rcs C2 OC1 Optcupler Z1 R5 R3 C1 R4 Clad Figure 4: 30W, Tw-Pair, Single Output Cnfiguratin The POE30U midspan can deliver 30W f pwer t the cable by injecting 550mA at 56V. A single NCP1081 delivers 20W t a 24V utput. The PE-PD efficiency frm input RJ45 jack t utput is estimated t be 85 percent. Using a Cat5e 100m cable results in an verall efficiency frm PSE utput t PD cnverter utput f 75 percent. The POE480U-4P can deliver 36W f pwer t the cable by injecting 720mA at 56V. A single NCP1081 delivers 25W t a 24V utput. The PE-PD efficiency frm input RJ45 jack t utput is estimated n 85 percent. Using a Cat5e 100m cable results in an verall efficiency frm PSE utput t PD cnverter utput f 71 percent. The pwer can be increased t higher pwer levels by increasing the vltage r current limit. Cnnecting the NCP1081 t a Phihng midspan keeps the nclass_at pin high. Rev. 2 Page 5 f 8

6 3.2 60W r 80W Triple Output Figure 5: 80W, Fur-Pair, Triple Output Cnfiguratin The POE60U midspan can deliver 60W f pwer t the cable by injecting 550mA at 56V. Dual NCP1081 s deliver 25W t a 24V utput, 20W t a 12V utput and 5W t a 3.3V utput. The PE-PD efficiency frm input RJ45 jack t utput is estimated t be 85 percent. Using a Cat5e 100m cable results in an verall efficiency frm PSE utput t PD cnverter utput f 75 percent. The POE80U midspan can deliver 80W f pwer t the cable by injecting 720mA at 56V. Dual NCP1081 s deliver 34W t a 24V utput, 30W t a 12V utput and 4W t a 3.3V utput. The PE-PD efficiency frm input RJ45 jack t utput is estimated t be 85 percent. Using a Cat5e 100m cable results in an verall efficiency frm PSE utput t PD cnverter utput f 71 percent. Cnnecting the NCP1081 t a Phihng midspan keeps the pin nclass_at high. Rev. 2 Page 6 f 8

7 3.3 60W r 80W Dual Output Figure 6: 80W, Fur-Pair, Dual Output Cnfiguratin The POE60U midspan can deliver 60W f pwer t the cable by injecting 550mA at 56V. Dual NCP1081 s deliver 25W t a 24V utput and 25W t a 12V utput. The PE-PD efficiency frm input RJ45 jack t utput is estimated t be 85 percent. Using a Cat5e 100m cable results in an verall efficiency frm PSE utput t PD cnverter utput f 75 percent. Other vltages can be derived frm the 12V utput with a separate DC-DC cnverter. The POE80U midspan can deliver 80W f pwer t the cable by injecting 720mA at 56V. Dual NCP1081 s deliver 34W t a 24V utput and 34W t a 12V utput. The PE-PD efficiency frm input RJ45 jack t utput is estimated t be 85 percent. Using a Cat5e 100m cable results in an verall efficiency frm PSE utput t PD cnverter utput f 71 percent. Other vltages can be derived frm the 12V utput with a separate DC-DC cnverter. Cnnecting the NCP1081 t a Phihng midspan keeps the pin nclass_at high. Rev. 2 Page 7 f 8

8 4.0 Cmpany r Prduct Inquiries Fr mre infrmatin abut ON Semicnductr s Pwer ver Ethernet prducts visit ur Web site at Revisin Histry Date Versin Mdificatins January Initial release April General update ON Semicnductr and are registered trademarks f Semicnductr Cmpnents Industries, LLC (SCILLC). SCILLC reserves the right t make changes withut further ntice t any prducts herein. SCILLC makes n warranty, representatin r guarantee regarding the suitability f its prducts fr any particular purpse, nr des SCILLC assume any liability arising ut f the applicatin r use f any prduct r circuit, and specifically disclaims any and all liability, including withut limitatin special, cnsequential r incidental damages. Typical parameters which may be prvided in SCILLC data sheets and/r specificatins can and d vary in different applicatins and actual perfrmance may vary ver time. All perating parameters, including Typicals must be validated fr each custmer applicatin by custmer's technical experts. SCILLC des nt cnvey any license under its patent rights nr the rights f thers. SCILLC prducts are nt designed, intended, r authrized fr use as cmpnents in systems intended fr surgical implant int the bdy, r ther applicatins intended t supprt r sustain life, r fr any ther applicatin in which the failure f the SCILLC prduct culd create a situatin where persnal injury r death may ccur. Shuld Buyer purchase r use SCILLC prducts fr any such unintended r unauthrized applicatin, Buyer shall indemnify and hld SCILLC and its fficers, emplyees, subsidiaries, affiliates, and distributrs harmless against all claims, csts, damages, and expenses, and reasnable attrney fees arising ut f, directly r indirectly, any claim f persnal injury r death assciated with such unintended r unauthrized use, even if such claim alleges that SCILLC was negligent regarding the design r manufacture f the part. SCILLC is an Equal Opprtunity/Affirmative Actin Emplyer. This literature is subject t all applicable cpyright laws and is nt fr resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: Literature Distributin Center fr ON Semicnductr P.O. Bx 5163, Denver, Clrad USA Phne: r Tll Free USA/Canada Fax: r Tll Free USA/Canada rderlit@nsemi.cm N. American Technical Supprt: Tll Free USA/Canada Eurpe, Middle East and Africa Technical Supprt: Phne: Japan Custmer Fcus Center Phne: ON Semicnductr Website: Order Literature: Fr additinal infrmatin, please cntact yur lcal Sales Representative Rev. 2 Page 8 f 8