100 meter cable charged to 500V * cable discharge test using one twisted pair cable (Hspice) * * the RJ-45 contacts are modeled as voltage controlled resistors * the timing of the physical contact mating is simulated by applying * a timing relationship on these VCR's * * the single twisted pair cable is initially charged and is open on both ends * then it is plugged in at one end (the near end) * the input contains a 1:1 transformer with a center tap. * that center tap is hooked to the common mode termination: 75 ohm in series with a 1nF cap ********************************************************************** * analysis type and options ********************************************************************** .tran 1n 10u 0 0.5n .options list node post *.options accurate .probe i(rlimit1) i(rlimit2) i(r_comterm) ********************************************************************** * differential measurements ********************************************************************** e_primary diff_primary 0 input_a input_b 1 r_diffpri diff_primary 0 1e6 e_secondary diff_secondary 0 sec1 sec2 1 r_diffsec diff_secondary 0 1e6 ********************************************************************** * initial conditions, the cable is charged up here in advance of plugging in ********************************************************************** .param init_cable_v = 500VDC .param init_common_cap_v = 0VDC * initial conditions on the twisted pair cable .ic v(farend_a) = init_cable_v .ic v(farend_b) = init_cable_v * initial conditions on the common mode termination cap .ic v(cap_term)= init_common_cap_v ********************************************************************** * common mode termination ********************************************************************** * PCB trace to the termination******** * lossy line model with length in meters, 0.0254 (meters) = 1 inch ucentertap center_tap 0 com_term 0 stripmod L=.015 * the resistive part of the termination r_comterm com_term cap_term 75 * the high voltage cap to frame ground ***** c_hi_v cap_term cap1 1000p l_cap cap1 cap2 1.5n r_cap cap2 0 0.62 * capacitor leakage r_shuntcap cap_term 0 1e8 ********************************************************************** * Simulation of plugging in the RJ-45 ********************************************************************** * the RJ-45 contacts are modeled as a voltage controlled resitor * this does not simulate any contact bounce gswitch1 input_a nearend_a VCR PWL(1) cntrl1 0 0V,100meg 1V,0.1 gswitch2 input_b nearend_b VCR PWL(1) cntrl2 0 0V,100meg 1V,0.1 * the following sources generate the timing of the two RJ-45 pins mating * here, the time difference is 5us between the first pin mating and the second pin mating * that corresponds to a difference in the RJ-45 pin lengths of about 0.1 mils (1E-4 inches) * combined with an insertion speed of 20 inches per second * the key is that for that first 5us period, only one RJ-45 pin has mated vcntrl1 cntrl1 0 pulse 0 1V 100n 0.1n 0.1n 1000u 2000u vcntrl2 cntrl2 0 pulse 0 1V 5.1u 0.1n 0.1n 1000u 2000u * trace to the XFMR ***** * lossy line model with length in meters, 0.0254 (meters) = 1 inch upri1 input_a 0 input_aa 0 stripmod L=.01 upri2 input_b 0 input_bb 0 stripmod L=.01 ********************************************************************** * the data XFMR ********************************************************************** x_xfmr1 input_aa input_bb center_tap sec1 sec2 0 dataxfmr ********************************************************************** * the secondary side of the data XFMR ********************************************************************** * terminate the secondary of the XFMR ***** * lossy line model with length in meters, 0.0254 (meters) = 1 inch uclamp1 sec1 0 sec1a 0 stripmod L=.0254 uclamp2 sec2 0 sec2a 0 stripmod L=.0254 rterm sec1a sec2a 100 * a simple voltage zener clamp on the PHY for demonstration purposes only * comment this out to see behavior without the clamp *rlimit1 sec1a clamp1a 0.1 *llimit1 clamp1a clamp1b 10n *xdiode1 0 clamp1b d1n4733 *rlimit2 sec2a clamp2a 0.1 *llimit2 clamp2a clamp2b 10n *xdiode2 0 clamp2b d1n4733 ********************************************************************** * the single twisted pair model ********************************************************************** * lossy coupled line from RLGC * length conversion: 25 feet is 300 inches, 100 meters is 3937 inches * the file: cat5_rlc.rlc contains RLGC parameters in length of inches .param cable_length = 3937 W1 N=2 nearend_a nearend_b 0 farend_a farend_b 0 RLGCfile=cat5_rlc.rlc L=cable_length * the far end of the cable is open, but we need a DC path to ground to satisfy Spice.... rplus farend_a 0 100meg rminus farend_b 0 100meg ********************************************************************** * subcircuits and models ********************************************************************** * 10/100 data XFMR .SUBCKT dataxfmr ina inb in_ct outa outb out_ct ****************************************************** * ina_________ _______outa * ) ( * ) ( * ) ( * ) ( * ___) (___ * in_ct___| |___out_ct * |___ ___| * ) ( * ) ( * ) ( * ) ( * inb_________) (_______outb ****************************************************** *** primary L1 ina in2 20n C1 in2 in6 5.7p L3 in2 in3 40n R3 in3 in4 0.8 Lina in4 in_ct 200u Rmag1 in4 ina4 0.01 Lmag1 ina4 in_ct 220u Rinshunt in4 in8 8100 Rmag2 in8 ina8 0.01 Lmag2 in_ct ina8 220u Linb in_ct in8 200u L2 inb in6 20n L4 in6 in7 40n R4 in7 in8 0.8 *** coupling c_couple in_ct out_ct 2p K1 Lina Linb 1.0 K2 Lina Louta 1.0 K3 Lina Loutb 1.0 *** secondary Louta out9 out_ct 200u Loutb out_ct out12 200u R6 out9 out10 0.8 L5 out10 outa 40n R7 out12 out13 0.8 L6 out13 outb 40n C2 outa outb 6.4p .ends dataxfmr * pc board trace, dimensions are in meters, 1 mil = 2.54E-5 meters, or 25.4u (meters) .model stripmod U level=3 plev=1 elev=1 dlev=2 NL=1 ht=350u wd=254u + th=36u ts=812u kd=4.0 * model of pcb stackup (lossy stripline transmission line) *.model u1 u level=3 plev=1 elev=1 nl=1 *+ th=1.37mil ht=5.5mil ts=19.74mil kd=4.4 dlev=2 *+ wd=5mil xw=-0.5mil * level: 3=lossy transmission line model * plev: transmission line physical model (1=planar, 2=coax, 3=twinlead) * elev: 1=geometry, 2=precomputed caracteristics * nl: number of conductors (traces) * th: conductor thickness (1 oz copper or 0.5 oz copper) * ht: conductor hight (distance of trace above plane) * ts: distance between planes * kd: dielectric constant * dlev: 0=trace over plane (1 dialectric) * 1=microstrip, * 2=stripline, * 3=trace over plane (2 dialectrics) * wd: width of trace * xw: difference between drawn and realized trace width .alter 50 meter cable charged to 500V .param cable_length = 1968 .param init_cable_v = 500VDC .alter 25 meter cable charged to 500V .param cable_length = 984 .param init_cable_v = 500VDC .alter 100 meter cable charged to 1000V .param cable_length = 3937 .param init_cable_v = 1000VDC .alter 50 meter cable charged to 1000V .param cable_length = 1968 .param init_cable_v = 1000VDC .alter 25 meter cable charged to 1000V .param cable_length = 984 .param init_cable_v = 1000VDC .end