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october 2010 doc id 17429 rev 1 1/64 AN3213 application note st7570 s-fsk power line networking system-on-chip design guide for amr introduction the st7570 demonstration board has been realized as a useful tool which exploits the performance capability of the st7570 s-fsk power line networking system -on-chip ( references 1 ). with this demonstration board, it is possible to evaluate the st7570 features and its transmitting and receiving performance directly on the power line. the coupling interface is designed to allow the st7570 device to transmit and receive on the mains using a spread-spectrum fsk signal with 63.3 and 74 khz tone frequencies, within the european cenelec en50065-1 standard a-band, specified for automatic meter reading ( references 4 ). figure 1. st7570 demonstration board with outline dimensions as can be seen from figure 1 , special effort has been made to make the demonstration board as compact as possible, while including all the features which enable the st7570 to perform at its best. note: the information provided in this application note refers to the evalst7570-1 demonstration board. www.st.com
contents AN3213 2/64 doc id 17429 rev 1 contents 1 abbreviations used in this docum ent . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 safety recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4 st7570 s-fsk power li ne networking system-on- chip description . . 12 5 demonstration tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 6 test and measurement tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7 st7570 demonstration board descr iption . . . . . . . . . . . . . . . . . . . . . . 15 7.1 line coupling section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 7.1.1 transmission active filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 7.1.2 reception passive filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7.1.3 power line coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 7.1.4 zero crossing coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 7.1.5 input impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 7.2 conducted disturbances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 7.2.1 conducted emission (ce) measurements . . . . . . . . . . . . . . . . . . . . . . . 35 7.2.2 noise immunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.2.3 awgn tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 7.2.4 nbi tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 7.3 pcb layout guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 7.3.1 thermal performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 7.3.2 ground connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.3.3 oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.4 thermal impedance and power dissipation calculation . . . . . . . . . . . . . . 43 7.5 oscillator section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.6 surge and burst protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 7.7 power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 8 application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 AN3213 contents doc id 17429 rev 1 3/64 8.1 three-phase architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 8.2 received signal strength indica tion (rssi) . . . . . . . . . . . . . . . . . . . . . . . 51 9 faqs and troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 9.1 faqs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 9.2 troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 10 references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 11 normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 appendix a board layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 list of tables AN3213 4/64 doc id 17429 rev 1 list of tables table 1. electrical and thermal characteristics of the st7570 demonstration board . . . . . . . . . . . . . 8 table 2. tx_out level vs. tx_gain - typical values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 table 3. bom list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 table 4. st parts on board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 table 5. line coupling transformer specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 table 6. noise level sn0 and sn1 during awgn tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 table 7. narrow-band interferer immunity test settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 table 8. document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 AN3213 list of figures doc id 17429 rev 1 5/64 list of figures figure 1. st7570 demonstration board with outline dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 figure 2. i(vcc) vs. i(pa_out) curve - typical values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 figure 3. st7570 block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 figure 4. board drawing with indication of the various sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 figure 5. global view of the st7570 demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 figure 6. st7570 schematic circuit (part 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 figure 7. power supply section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 figure 8. uart interface section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 figure 9. external microcontroller connection section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 figure 10. st7570 schematic circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 figure 11. reset circuit section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 figure 12. jtag lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 figure 13. current limit setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 figure 14. non-isolated zero crossing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 figure 15. usb to uart connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 figure 16. reception and transmission filter schematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 figure 17. measured frequency response of the transmission active filter (typical) . . . . . . . . . . . . . . 27 figure 18. montecarlo simulation of the transmission active filter frequency response . . . . . . . . . . . . 28 figure 19. measured frequency response of the reception passive filter (typical) . . . . . . . . . . . . . . . . 29 figure 20. montecarlo simulation of the reception passive filter response . . . . . . . . . . . . . . . . . . . . . 30 figure 21. measured frequency response of the tx active + passive filter loaded with the en50065-1 lisn impedance (typical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 figure 22. montecarlo simulation of the transmission line coupling response loaded with the en50065-1 lisn impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 figure 23. non-isolated zero crossing coupling circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 figure 24. zc_in_a vs. mains voltage - delay measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 figure 25. zc_in_a vs. mains voltage - jitter measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 figure 26. measured input impedance modulus of the line coupling - reception mode (typical) . . . . . 35 figure 27. measured input impedance modulus of the line coupling - transmission mode (typical) . . 35 figure 28. conducted emissions test setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 figure 29. conducted emissions: transmission spec trum, quasi-peak measurement, 3 khz - 150 khz, line-to-earth, as per en50065-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 figure 30. conducted emissions: transmission spec trum, quasi-peak measurement, 3 khz - 150 khz, neutral-to-earth, as per en50065-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 figure 31. conducted emissions: transmission spec trum, quasi-peak measurement, 150 khz - 30 mhz, line-to-earth, as per en50065-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 figure 32. conducted emissions: transmission spec trum, quasi-peak measurement, 150 khz - 30 mhz, neutral-to-earth, as per en50065-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 figure 33. noise immunity test setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 figure 34. measured ber vs. snr curve (typical), white noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 figure 35. example of stencil openings for the qfn48 package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 figure 36. pcb copper dissipating area on top layer for the st7570 demonstration board . . . . . . . . 42 figure 37. pcb copper dissipating area on bottom layer for the st7570 demonstration board . . . . . 42 figure 38. packet-fragmented transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 figure 39. measured st7570 thermal impedance curve (typical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 figure 40. simulation model of the thermal impedance zthja of the st7570 mounted on the demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 figure 41. carrier frequency deviation vs. crystal tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 list of figures AN3213 6/64 doc id 17429 rev 1 figure 42. delay between mains zero crossing and transmission start: jitter vs. crystal tolerance . . . 46 figure 43. common mode disturbance protection - positive disturbance . . . . . . . . . . . . . . . . . . . . . . 47 figure 44. common mode disturbance protection - negative disturbance. . . . . . . . . . . . . . . . . . . . . . 48 figure 45. differential mode disturbances protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 8 figure 46. example of power supply emi input filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 figure 47. scheme of principle for non-switched three-phase architecture . . . . . . . . . . . . . . . . . . . . . 50 figure 48. scheme of principle for switched three-phase architecture . . . . . . . . . . . . . . . . . . . . . . . . 51 figure 49. snr0 estimator at 1200 bps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 figure 50. snr1 estimator at 1200 bps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 figure 51. snr0 estimator at 2400 bps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 figure 52. snr1 estimator at 2400 bps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 figure 53. pcb layout - component placing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 figure 54. pcb layout - top view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 figure 55. pcb layout - bottom view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 AN3213 abbreviations used in this document doc id 17429 rev 1 7/64 1 abbreviations used in this document ac = alternate current afe = analog front end amr = automated meter reading awgn = additive white gaussian noise ber = bit error rate bom = bill of material ce = conducted emissions dc = direct current emc = electro-magnetic compliance emi = electro-magnetic immunity gui = graphical user interface mac = medium access control layer (as per iec61334-5-1 protocol stack definition - references 5 ) nbi = narrow-band interferer lisn = line impedanc e stabilization network pa = power amplifier pcb = printed circuit board phy = physical layer (as per iec61334-5-1 protocol stack definition - references 5 ) plc = power line communication psu = power supply unit rbw = resolution bandwidth sbw = signal bandwidth s-fsk = spread frequency shift keying snr = signal-to-noise ratio ssd = start subframe delimiter (as per iec61334-5-1 physical layer definition - references 5 ) electrical characteristics AN3213 8/64 doc id 17429 rev 1 2 electrical characteristics table 1. electrical and thermal characteristics of the st7570 demonstration board parameter value notes min typ max thermal data ambient operating temperature -40 c 85 c st7570 thermal resistance 50 c/w ( (1) ) measured on the st7570 demonstration board 2-side pcb with thermal pad and 4x4 thermal via array transceiver section transmitting specifications (tx mode) transmitted signal tone ?1? frequency 63.3 khz transmitted signal tone ?0? frequency 74 khz transmitted signal -20 db bandwidth 19 khz 2400 baud transmitted output current limit 1 a rms r15 = 130 ? receiving specifications (rx mode) minimum detectable received signal 46 dbv rms 1200 baud, ber<10 -3 , snr > 20 db reception filter -3 db bandwidth 50 khz mains coupling specifications transformer isolation 4 kv ( (2) ) power supply requirements ac mains voltage range 85 v ac 265 v ac mains frequency 50-60 hz vcc power supply voltage 8 v 13 v 18 v vcc power supply current absorption ? rx mode 12 ma dl1 on (7 ma typ.) AN3213 electrical characteristics doc id 17429 rev 1 9/64 vcc power supply current absorption ? tx mode 20 ma 500 ma vcc = 8 to 18 v, i(pa_out) = 0 to 1 a rms vddio digital supply voltage -10 % 3.3 v +10 % vddio digital supply current absorption 40 ma dl2 on (5 ma typ.), no external microcontroller connection through j1 maximum required power (typical application) 7 w vcc = 13 v 1. measured over a continuous tr ansmission period of 3000 seconds (st eady-state thermal dissipation). 2. note that stmicroelectronics does not guarantee transformer isolation. stmi croelectronics assumes no responsibility for the consequences that may arise from that risk. table 1. electrical and thermal characteristics of the st7570 demonstration board (continued) parameter value notes table 2. tx_out level vs. tx_gain - typical values tx_gain tx_out [dbv rms] [v rms] 31 123 1.420 30 122 1.265 29 121 1.128 28 120 1.005 27 119 0.896 26 118 0.798 25 117 0.712 24 116 0.634 23 115 0.565 22 114 0.504 21 113 0.449 20 112 0.400 19 111 0.357 18 110 0.318 17 109 0.283 16 108 0.252 15 107 0.225 14 106 0.201 electrical characteristics AN3213 10/64 doc id 17429 rev 1 figure 2. i(vcc) vs. i(pa_out) curve - typical values 13 105 0.179 12 104 0.159 11 103 0.142 10 102 0.127 9 101 0.113 8 100 0.101 7 99 0.090 6 98 0.080 5 97 0.071 4 96 0.063 3 95 0.057 2 94 0.050 1 93 0.045 table 2. tx_out level vs. tx_gain - typical values (continued) tx_gain tx_out ! - v , 3 $ b 2 8 7 > p $ @ , 9 & |