RS-485EVALBOARD2 Bourns

RS-485 Port Protection Evaluation Board 2 Introduction This evaluation board serves as an aid in Line A Unprotected 40 mils traceProtected Load A 2 1 2 2 evaluating circuit protection on RS-485 1 III 1 1 TBU HSP 1 serial device port solutions using Bourns 3 NU J1 J3 TVS1 TVS3 MOV1 GDT1 TISP1 2 I II TBU High-Speed Protector (HSP), MOV TVS5 1 3 3 and TVS products to meet the required GDT3 2 II I industry standards on RS-485 port 2 3 NU TVS2 TVS4 MOV2 GDT2 TISP2 interfaces. The recommended Bourns 1 II I 1 1 TBU HSP 2 TBU HSP solution oerff s enhanced 12 2 2 Line B Unprotected 40 mils traceProtected Load B performance features over competing J2 J4 technologies, which can help the design Figure 1 RS-485 Evaluation Board 2 Schematic engineer to increase the surge & transient protection level on RS-485 ports and place the entire circuit protection solution into a smaller PCB area. Bourns has developed a RS-485 evaluation board (measuring 50 mm x 25 mm x 1.2 mm) manufactured using FR4 PCB with nickel gold plating on top and bottom sides. How to Connect the Evaluation Board for Test Set-up Connect J1 and J2 to the exposed lines. Connect J3 and J4 to the RS-485 IC device. Figure 2 RS-485 Evaluation Board 2 Top Side Layout* * In addition to the two TBU HSPs, the default Table 1 RS-485 Evaluation Board 2 Bill of Materials congfi uration of this board uses two MOVs (MOV1, MOV2) and a single TVS diode array (TVS5). The board allows dierff ent congfi urations: No. Part Number Qty. Description Reference 2 MOVs (MOV1 and MOV2) may be replaced by a) 2 single 2031 GDTs (GDT1 and GDT2) 1 TBU-CA065-300-WH 2 TBU Single Bidirectional Line 650 V 300 mA TBU HSP 1, TBU HSP 2 or b) a dual 2030 GDT (GDT3, not yet released) 1 TVS diode array (TVS3) may be replaced with 2 MOV-10D201K 2 Single Line 10 mm MOV 200 V MOV1, MOV2 a) 2 SMB TVS diodes (TVS1, TVS2) or b) 2 SOT23 TVS diodes (TVS3, TVS4) or c) 2 SOT23-5 thyristor 3 CDSOT23-SM712 2 Dual Bidirectional Line 7 V / 12 V TVS5 devices (TISP1, TISP2) 5/11 FU1107 1 2 21 21 12 21RS-485 Port Protection Evaluation Board 2 Performance Graphs Run T Trig PreVu T Trig T T Ch1 Max Ch1 Max 545 V 329 V Ch1 Min Ch1 Min 1 1 4 4 -20.5 V -390 V Ch4 Max Ch4 Max 11.3 mA 1.98 A Ch4 Min Ch4 Min -81.1 mA -2.55 A Ch1 500 V MA10.0 ns Ch1 -380 V Ch1 200 V MA400 ns Ch1 116 V Ch4 5.00 A Ch4 1.00 A T 20.40 % T 31.60 % Ch 1: input voltage / surge / fault to TBU HSP Ch 1: input voltage / surge / fault to TBU HSP The ohm unit following the current units The ohm unit following the current units Ch 4: TBU HSP current Ch 4: TBU HSP current shown for Channel 4 (i.e. AOhm) shown for Channel 4 (i.e. AOhm) indicates that a 50 ohm termination was indicates that a 50 ohm termination was used internal to the oscilloscope used internal to the oscilloscope Figure 3 ESD +8 KV Contact Discharge (IEC-61000-4-2) Figure 4 Surge 1.2/50 5 KV Run T Trigd Run T Trigd T T Ch1 Max Ch1 Max 124.4 V 28.3 V 1 Ch4 Max 1 Ch4 Max 4 4 365.4 mA 451.8 mA Ch4 Min Ch4 Min -322.4 mA -395.7 mA Ch1 100 V MA4.00 ms Line 116 V Ch1 20.0 V MA4.00 ms Line 116 V Ch4 200 mA Ch4 200 mA T 20.20 % T 20.20 % Ch 1: input voltage / surge / fault to TBU HSP Ch 1: input voltage / surge / fault to TBU HSP The ohm unit following the current units The ohm unit following the current units Ch 4: TBU HSP current Ch 4: TBU HSP current shown for Channel 4 (i.e. AOhm) shown for Channel 4 (i.e. AOhm) indicates that a 50 ohm termination was indicates that a 50 ohm termination was used internal to the oscilloscope used internal to the oscilloscope Figure 5 120 V Figure 6 28 V rms rms Reference For more information on implementing advanced circuit protection technologies for RS-485 ports, please review the Bourns RS-485 application note: