IEEE802.3bt Cable Balance Ad-Hoc

Transcription

1 IEEE802.3bt Cable Balance Ad-Hoc PSE & PD Powered Interface (PI) Specifications Models, Values and Current Balance Results Rev 1.26 J. Heath Linear Technology

2 2 PSE & PD PI Definition and Current Imbalance Method Determine reasonable Thevenin values for the PSE PI and PD PI based on current PSE design knowledge base Goal: Provide implementation independent and testable PI interfaces for the PSE & PD that ensure interoperability Simulate all 3 system components (the two PIs and the link segment or channel) with careful selection of worst case values at multiple current levels. The proposed ad-hoc products are the highest individual pair current vs power level and the PSE PI and PD PI. (Not a % current imbalance number)

3 3 End to End Current Model including PSE PI, PD PI, and Channel PSE PI PD PI Vps1 Rps1 Alt A + Rc1 Alt A + Rpd1 PD Vpd1 Vps Rps2 Alt B + Rc2 Alt B + Rpd2 Vpd2 PD Iload Vps2 Rps3 Alt A - Rc3 Alt A - Rpd3 Vpd3 Rps4 Alt B - Rc4 Alt B - Rpd4 Vpd4 Channel

4 4 Channel Imbalance Maximum Channel 2 pair Resistance 100m Cat5 Channel 12.5 ohms (TBR) Cat6 Close to Cat5 (TBD) Wayne Larsen is suggesting lesser 100m Channel Resistance Pair to Pair Imbalance Greater of (7% of total channel resistance) or.2 ohms (TBR) Model under review. Channel

5 Length (m) Channel Rmax Channel Rmin Calculated Rchannel Imbalance If By % 5 Simplified Cable Resistance and Rimbalance CAT5e vs. Length Channel Max Length 100 m ohms Max 2 Pair PoE Round Trip Channel Resistance 12.5 ohms Max 1 Pair Resistance (one way) 6.25 ohms Ratio Imbalance 7% ohms/ohm Min Imbalance 0.2 ohms Starting Point is Maximum Pair Resistance for Max Pair Special Case Max Min => Imbalance

6 6 Keeping the PSE & PI Definitions Implementation Independent Delta resistance values and delta voltage values are the best way to keep the PI definition implementation independent PI definition does not include total resistance, just delta resistance We are NOT attempting to telling the OEMs how much resistance they can have in a PSE or PD (A single point PI measurement cannot fully characterize a PSE or PI.)

7 7 PSE PI Values and Simulation Support Information (Included DCMPS & ACMPS for now) PI Spec DCMPS ACMPS System Simulation Support DCMPS ACMPS Rps1,Rps2 abs(rps1 - Rps2) ohms Rps1,Rps2 Max ohms ohms Rps1,Rps2 Min ohms Vps1 abs(maximum) Volts Vps1max Volts Vps1min Rps3,Rps4 abs(rps3 - Rps4) ohms Rps3, Rps4 Max ohms ohms Rps3, Rps4 Min ohms Vps2 abs(maximum) Volts Vps2 Max Volts Vps2 Min Volts Vps *See Simulation Schematic Vps Max Volts Vps Min Volts ACMPS Diodes Rps1 -> 4 Max ohms Rps1 -> 4 Max ohms Vps1, Volts Vps1,2 Max Volts Vps1,2 Min Volts

8 8 PSE PI Values and Simulation Support Information (Included DCMPS & ACMPS for now) PI Spec DCMPS ACMPS System Simulation Spport DCMPS ACMPS Rps1,Rps2 abs(rps1 - Rps2) ohms Rps1,Rps2 Max ohms ohms Rps1,Rps2 Min ohms Vps1 ABS(Maximum) Volts Vps1max Volts Vps1min Rps3,Rps4 abs(rps3 - Rps4) ohms Rps3, Rps4 Max ohms ohms Rps3, Rps4 Min ohms Vps2 ABS(Maximum) Volts Vps2 Max Volts Vps2 Min Volts Vps See Simulation Schematic Vps Max Volts Vps Min Volts ACMPS Diodes ohms ohms Volts Max Volts Min Volts

9 9 PD PI Values and Simulation Support Information PI Spec DCMPS System Simulation Support DCMPS Rpd1,Rpd2 abs(rpd1 - Rpd2) ohms Rpd1,Rpd2 Max ohms ohms Rpd1,Rpd2 Min ohms Vpd1,Vpd2 abs(vpd1-vpd2) Volts Vpd1,Vpd2 Max Volts Vpd1,Vpd2 Min Rpd3,Rpd4 abs(rpd3 - Rpd4) ohms Rpd3, Rpd4 Max ohms ohms Rpd3, Rpd4 Min ohms Vpd3,Vpd4 abs(vpd3 - Vpd4) Volts Vpd3,Vpd4 Max Volts Vpd3,Vpd4 Min Volts

10 10 System Simulation Schematic Worst Case Vps1 + Vps Rps1 Rps2 H = High L = Low PSE PI PD PI H PD + Alt A + Smaller Alt A + Vpd1 H Rc1 H Rpd1 H L + Alt B + Bigger Alt B + Vpd2 Iload L Rc2 L Rpd2 L PD Vps2 + Rps3 Rps4 Alt A - Smaller Alt A - H Rc3 H Rpd3 H Alt B - Bigger Alt B - L Rc4 L Rpd4 L H + Vpd3 L + Vpd4 Channel

11 Max Single Pair Current PD Power (W) Short Channel I (ma) Long Channel I (ma) Mair Max (ma) 11 Maximum Pair System Current vs Power Today s Results PD Power

12 12 Values and Results Values are simulated in LTSpice Maximum pair current reported in each simulation condition and then the maximum of these maximums is reported Re-simulation will be required as values continue to change

13 13 To Do Follow the continuing resistance and voltage parameters as they evolve and re-simulate Add AC disconnect diodes to the PSE PI and adjust PSE PI values and re-simulate Simulate the 4 channel length resistances for 0.15m, 4m, 23m, 100m Wayne is suggesting using his values. Create a different and more realistic PSE and PD that could be useful for looking at the upcoming DC disconnect discussions

14 Backup Material J. Heath

15 Max Single Pair Current PD Power (W) Short Channel I (ma) Long Channel I (ma) Mair Max (ma) 15 Maximum Pair System Current vs Power Today s Results PD Power

16 Pair Current 16 Maximum Pair System Current vs Power PD Power

17 Pair Current 17 Simplified Diode Model Results at Low Currents Suggest a Better Model Would be Useful PD Power

18 18 Starting With the Channel PSE PI PD PI Vps1 Rps1 Alt A + Rc1 Alt A + Rpd1 PD Vpd1 Vps Rps2 Alt B + Rc2 Alt B + Rpd2 Vpd2 PD Iload Vps2 Rps3 Alt A - Rc3 Alt A - Rpd3 Vpd3 Rps4 Alt B - Rc4 Alt B - Rpd4 Vpd4 Channel

19 19 Some Channel Imbalance Values from Wayne Larsen for Simulations Channel rnom connector % 5.00% Rimbalnce connector 30 cable length cordage length total length connectors A B C D max channel resistance min channel resistance channel unbalance, Ohms channel unbalance % A % B % C % D %

20 20 Channel Imbalance Maximum Channel 2 pair Resistance 100m Cat ohms (TBR) Cat6 Close to Cat5 (TBD) Pair to Pair Imbalance Channel Greater of (6% of total channel resistance) or.2 ohms (TBR)

21 Length (m) Channel Rmax Channel Rmin Calculated Rchannel Imbalance If By % 21 Cable Resistance and Rimbalance CAT5e vs. Length Channel Max Length 100 m ohms Max 2 Pair PoE Round Trip Channel Resistance 12.5 ohms Max 1 Pair Resistance (one way) 6.25 ohms Ratio Imbalance 7% ohms/ohm Min Imbalance 0.2 ohms Starting Point is Maximum Pair Resistance for Max Pair Special Case Max Min => Imbalance

22 22 Why Separate PSE & PD PI definitions and System Simulation Values? To stay away from implementation At the PSE & PD PI it is the differences between resistances and between voltages that cause current imbalance Delta resistance and voltage values cause current imbalance Large nominal resistances will ballast delta voltage values within the PSE and PD PIs. PSE and PD PI definitions can be specified in terms of worst case differences For system level simulations, separate High/Low values are determined and used for end to end simulation to calculate worst case current in any pair.

23 23 PSE PI PSE PI Vps1 Rps1 Alt A + Vps Rps2 Alt B + Vps2 Rps3 Rps4 Alt A - Alt B -

24 24 PSE PI Low Side Value Selection Assumes not ACMPS for now (we need to talk about this) With no ACMPS, V1 is just set to a reasonable non-zero value Vps2 Suggest 0.05V (TBR) Nominal System Simulation Support Rps3, Rps4 Imbalance Max Min Rfet (High R) ohms Rfet (Low R) ohms Rsense(High) ohms Rsense(Low) ohms Rtrace ohms Rmag ohms Rconn ohms PI Spec Totals ohms ACMPS? ACMPS? Rfet Rfet Rps3 Rtrace Rps4 Rtrace Rmag Rmag Rmag Rmag Rconn Rconn Rconn Rconn Alt A - Alt B -

25 25 PSE PI High Side Values Assumes not ACMPS for now Welcome input here With no ACMPS, V1 is just set to non-zero value Vps1 Suggest 0.05V Nominal System Simulation Support Rps1, Rps2 Imbalance Max Min Rfuse ohms Rtrace ohms Rmag ohms Rconn ohms PI Spec Totals ohms ACMPS? ACMPS? Rfuse Rfuse Rps1 Rtrace Rps2 Rtrace Rmag Rmag Rmag Rmag Rconn Rconn Rconn Rconn Alt A + Alt B +

26 26 PSE PI Values and Simulation Support Information (Included DCMPS & ACMPS for now) PI Spec DCMPS ACMPS System Simulation Support DCMPS ACMPS Rps1,Rps2 abs(rps1 - Rps2) ohms Rps1,Rps2 Max ohms ohms Rps1,Rps2 Min ohms Vps1 abs(maximum) Volts Vps1max Volts Vps1min Rps3,Rps4 abs(rps3 - Rps4) ohms Rps3, Rps4 Max ohms ohms Rps3, Rps4 Min ohms Vps2 abs(maximum) Volts Vps2 Max Volts Vps2 Min Volts Vps *See Simulation Schematic Vps Max Volts Vps Min Volts ACMPS Diodes Rps1 -> 4 Max ohms Rps1 -> 4 Max ohms Vps1, Volts Vps1,2 Max Volts Vps1,2 Min Volts

27 27 PD PI PD PI Alt A + Rpd1 PD Vpd1 Alt B + Rpd2 Vpd2 PD Iload Alt A - Rpd3 Vpd3 Alt B - Rpd4 Vpd4

28 28 PD PI High Side Values System Simulation Support Rpd1, Rpd2 Imbalance Max Min Rtrace ohms Rmag ohms Rconn ohms Rdoide(High) ohms Rdiode(Low) ohms PI Spec Totals ohms Vpd1,Vpd2 Vdiode Volts Rfet Rfet Rdiode Vdiode Rdiode Vdiode Rpd1 Rtrace Rpd2 Rtrace Rmag Rmag Rmag Rmag Rconn Rconn Rconn Rconn Alt A - Alt B -

29 29 PD PI Notes High Side MOSFET PDs exist Need to consider the possible impact if any on Maximum Current.

30 30 PD PI Low Side Values System Simulation Support Rpd3,Rpd4 Imbalance Max Min Rdoide(High) ohms Rdiode(Low) ohms Rtrace ohms Rmag ohms Rconn ohms Rfet (High R) ohms Rfet (Low R) ohms PI Spec Totals ohms Vpd3,Vpd4 Vdiode Volts Rfet Rfet Rdiode Vdiode Rdiode Vdiode Rpd3 Rtrace Rpd4 Rtrace Rmag Rmag Rmag Rmag Rconn Rconn Rconn Rconn Alt A - Alt B -

31 31 PD PI Values and Simulation Support Information PI Spec DCMPS System Simulation Support DCMPS Rpd1,Rpd2 abs(rpd1 - Rpd2) ohms Rpd1,Rpd2 Max ohms ohms Rpd1,Rpd2 Min ohms Vpd1,Vpd2 abs(vpd1-vpd2) Volts Vpd1,Vpd2 Max Volts Vpd1,Vpd2 Min Rpd3,Rpd4 abs(rpd3 - Rpd4) ohms Rpd3, Rpd4 Max ohms ohms Rpd3, Rpd4 Min ohms Vpd3,Vpd4 abs(vpd3 - Vpd4) Volts Vpd3,Vpd4 Max Volts Vpd3,Vpd4 Min Volts

32 Current Imbalance Simulations Jeff Heath

33 33 System Simulation Schematic PSE PI PD PI Vps1 Rps1 Alt A + Rc1 Alt A + Rpd1 PD Vpd1 Vps Rps2 Alt B + Rc2 Alt B + Rpd2 Vpd2 PD Iload Vps2 Rps3 Alt A - Rc3 Alt A - Rpd3 Vpd3 Rps4 Alt B - Rc4 Alt B - Rpd4 Vpd4 Channel

34 34 System Simulation Schematic Worst Case Vps1 + Vps Rps1 Rps2 H = High L = Low PSE PI PD PI H PD + Alt A + Smaller Alt A + Vpd1 H Rc1 H Rpd1 H L + Alt B + Bigger Alt B + Vpd2 Iload L Rc2 L Rpd2 L PD Vps2 + Rps3 Rps4 Alt A - Smaller Alt A - H Rc3 H Rpd3 H Alt B - Bigger Alt B - L Rc4 L Rpd4 L H + Vpd3 L + Vpd4 Channel

35 Pair Current 35 Maximum Pair System Current vs Power PD Power

36 Pair Current 36 Simplified Diode Model Results at Low Currents PD Power

37 37 Long Channel Simulation Values Long Channel Values PSE Values PD Values Channel Values Rc1,Rc3 Rc2,Rc4 Rps1,Rps2 Max ohms Rpd1,Rpd2 Max ohms Length(m) Channel Rmax Channel Rmin abs(rps1 - Rps2) ohms abs(rpd1 - Rpd2) ohms Rpse ohms Rpd ohms Rpse ohms Rpd ohms Rps3, Rps4 Max ohms Rpd3, Rpd4 Max ohms abs(rps3 - Rps4) ohms abs(rpd3 - Rpd4) ohms Rpse ohms Rpd ohms Rpse ohms Rpd ohms Vpd Volts Vpse Vpd1,Vpd2 Max Volts VPSE out Min Volts abs(vpd1-vpd2) Volts Vpse1 Vpd Volts abs(delta) Volts Vpd1,Vpd2 Max Vpse2 abs(delta) Volts Vpd Volts Vpd3,Vpd4 Max VRpse Volts abs(vpd3 - Vpd4) Vrpse Volts Vrpse Volts Vpd Volts Vrpse Volts Vpd3,Vpd4 Max 0.800

38 38 Short Channel Simulation Values Short Channel Values PSE Values PD Values Channel Values Rc1,Rc3 Rc2,Rc4 Rps1,Rps2 Min ohms Rpd1,Rpd2 Min 0.32 ohms Length(m) Channel Rmax Channel Rmin abs(rps1 - Rps2) ohms abs(rpd1 - Rpd2) ohms Rpse ohms Rpd ohms Rpse ohms Rpd ohms Rps3, Rps4 Min ohms Rpd3, Rpd4 Min 0.34 ohms abs(rps3 - Rps4) ohms abs(rpd3 - Rpd4) ohms Rpse ohms Rpd ohms Rpse ohms Rpd ohms Vpd Volts Vpse Vpd1,Vpd2 Max Volts VPSE out Min Volts abs(vpd1-vpd2) Volts Vpse1 Vpd Volts abs(delta) Volts Vpd1,Vpd2 Max Vpse2 abs(delta) Volts Vpd Volts Vpd3,Vpd4 Max VRpse Volts abs(vpd3 - Vpd4) Vrpse Volts Vrpse Volts Vpd Volts Vrpse Volts Vpd3,Vpd4 Max 0.800

39 39 Appendix A PSE PI Magnetics check Minimum Nominal: 0.09 ohms Delta: ohms Maximum Nominal: ohms Delta: ohms These Values differ from current assumptions I will use the new low nominal value and the existing high value Low: 0.09 ohms High: 0.13 ohms 0C Average Parallel R Average Average Delta C Average Delta

40 Resistance ohms Diode threshold Voltage (V) 40 Appendix B: Diode Mismatch Shows Much Larger Diode Resistance than Currently Being Modeled Diode R Vt Fairchild S1B Diodes 100V, 1A Mean Min Max Delta R Vt Diode Number

41 41 Current Diode Mismatch Parameters Seem Very Pessimistic. This is worth a discussion in the future VT=0.53 RS=0.40 VT=0.39 RS= VT=0.53 RS=0.40 VT=0.53 RS= ID 0.5 ID VD VD Current Diode Mismatch Model in this presentation. Diode Mismatch Model w/ more realistic R and Vth Mismatch