rs-485 evaluation board bill of materials table 1 no. part number qty. description reference 1 TBU-CA065-200-WH 2 tbu? single bidirectional line 650 v 200 ma tbu? hsp 1, tbu? hsp 2 2 2031-23t-sm-rplf 2 single line fast-acting gdt 650 v gdt1, gdt2 3 smbj12ca 2 single bidirectional line tvs 12 v smb tvs1, tvs2 introduction tis evaluation board serves as an aid in evaluating circuit protection on rs-485 serial device ports, using two bourns? tbu? high-speed protectors (hsp), two fast-acting gdts and two tvs diodes to meet the required industry standards on rs-485 port interfaces. te recommended bourns? tbu? device solution, with a low capacitance gdt, ofers enhanced high-speed performance features over competing technologies, which can help the design engineer increase the surge and transient protection level on rs-485 ports and place the entire circuit protection solution into a smaller reduced pcb area. bourns has developed an rs-485 evaluation board (measuring 45 mm x 21?mm x 1.2 mm) manufactured using fr4 pcb with nickel gold plating on the top and bottom sides. how to connect the evaluation board for test set-up ? connect in1 and in2 to the exposed lines. ? connect out1 and out2 to the rs-485 ic device. * te default confguration of this board uses 2 gdts (gdt1, gdt2) and discrete smb tvs diodes (tvs1,tvs2). te board allows diferent confgurations: ? 2 single 2031 gdts (gdt1 and gdt2) may be replaced by a dual 2030 gdt (gdt3) ? 2 smb tvs diodes (tvs1 and tvs2) may be replaced with a) 2 sot23 tvs diodes (tvs3, tvs4) or b) a single tvs diode array (tvs5) rs-485 evaluation board top side layout* rs-485 evaluation board schematic figure 2 figure 1 1 tbu? hsp 1 in1 in2 gnd out1 out2 gnd t vs5 t vs3 t vs4 t vs1 t vs2 gd t3 gd t1 gd t2 tbu? hsp 2 1 1 3 2 1 3 2 1 3 3 2 1 12 21 21 21 2 1 12 1 11 2 1 rs-485 port protection evaluation board 1 10/12 ? fu1213
power cross 120 v rms slew rate 1 kv/s slew rate 5 kv/s figure 3 figure 4 figure 5 ch 1: surge generator ch 2: c onsumed current (t bu? hsp tr igger current) note: the noise gener ated by the gd t when it ?res ca uses a ground bounce and is re?ected in current measurement at the time the gd t device is triggere d. 1 ch1 ch1 -172 v ma 200 ns 31.00 % 1.00 a ch4 200 v ch1 ma x 508 v tr ig? pr ev u ch4 ma x 1.74 a t t 4 the ohm unit following the current units shown for channel 4 (i. e. ao hm) indic ates that a 50 ohm termination w as used internal to the oscilloscope t ch 1: surge generator ch 2: c onsumed current (t bu? hsp tr igger current) note: the noise gener ated by the gd t when it ?res ca uses a ground bounce and is re?ected in current measurement at the time the gd t device is triggere d. 1 ch1 ch1 312 v ma 200 ns 30.40 % 1.00 a ch4 200 v ch1 ma x 625 v pr ev u ch4 ma x 1.64 a t t 4 the ohm unit following the current units shown for channel 4 (i. e. ao hm) indic ates that a 50 ohm termination w as used internal to the oscilloscope t reference for more information on implementing advanced circuit protection technologies for rs-485 ports, please review the bourns? rs-485 application note: http://www.bourns.com/data/global/pdfs/bourns_cpk1047_ rs485_circuit_protection_appnote.pdf ?tbu? is a registered trademark of bourns, inc. in the u.s., taiwan and european community. ?bourns? is a registered trademark of bourns, inc. in the u.s. and other countries. copyright? 2012 bourns, inc. 10/12 e/fu1213 for further technical support and for complete circuit protection solutions, please visit www.bourns.com ch 1: ac power generator ch 2: v oltage on protec ted side of world (downstream of tbu? device at smbj12ca tv s diode side) ch 4: cu rr ent consumed (t bu? hsp trigger current) 1 ch1 line -3.98 v ma 2.00 ms 27.20 % 20.0 v 200 ma ch2 ch4 200 v ch1 rms 126.7 v tr ig d run ch4 ma x 371.2 ma ch4 mi n -359.9 ma t t 2 4 the ohm unit following the current units shown for channel 4 (i. e. ao hm) indic ates that a 50 ohm termination w as used internal to the oscilloscope t rs-485 port protection evaluation board 1 performance graphs 10/12 ? fu1213
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