ST ST7538Q, Application Note

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List of figures AN2744
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List of figures
Figure 1. ST7538Q dual channel reference design board with outline dimensions . . . . . . . . . . . . . . . 1
Figure 2. Typical curve for output current limit vs. RCL value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 3. ST7538Q transceiver block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 4. Complete evaluation system including a PC, an EVALCOMMBOARD and the
EVALST7538DUAL board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 5. Power line modem demonstration kit with transmission session window . . . . . . . . . . . . . . 13
Figure 6. Scheme of the various sections of the board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 7. Modem and coupling interface schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 8. Power supply schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 9. Schematic of Rx and Tx filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 10. Measured frequency response of the Tx passive filter for 72 kHz channel (typical). . . . . . 22
Figure 11. Measured frequency response of the Tx passive filter for 86 kHz channel (typical). . . . . . 23
Figure 12. Simulated frequency response of the Tx passive filter for 72 kHz channel with tolerance
effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 13. Simulated frequency response of the Tx passive filter for 86 kHz channel with tolerance
effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 14. Measured frequency response of the Rx passive filter for 72 kHz channel (typical) . . . . . 25
Figure 15. Measured frequency response of the Rx passive filter for 86 kHz channel (typical) . . . . . 26
Figure 16. Simulated frequency response of the Rx passive filter for 72 kHz channel with tolerance
effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 17. Simulated frequency response of the Rx passive filter for 86 kHz channel with tolerance
effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 18. Measured frequency response of the Rx active filter for 72 kHz channel (typical) . . . . . . . 27
Figure 19. Measured frequency response of the Rx active filter for 86 kHz channel (typical) . . . . . . . 28
Figure 20. Simulated frequency response of the Rx active filter for 72 kHz channel with tolerance
effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 21. Simulated frequency response of the Rx active filter for 86 kHz channel with tolerance
effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 22. Measured input impedance magnitude of the coupling interface in Rx mode for the 72 kHz
channel (typical curve) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 23. Measured input impedance magnitude of the coupling interface in Rx mode for the 86 kHz
channel (typical curve) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 24. Measured input impedance magnitude of the coupling interface in Tx mode for the 72 kHz
channel (typical curve) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 25. Measured input impedance magnitude of the coupling interface in Tx mode for the 86 kHz
channel (typical curve) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 26. Conducted disturbance test setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 27. Output spectrum (typical) at 72 kHz channel, mains 220 VAC, fixed transmitted
tone = "1" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 28. Output spectrum (typical) at 86 kHz channel, mains 220 VAC, fixed transmitted
tone = "1" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 29. Narrowband conducted interference test setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 30. Measured BER vs. SNR curve (typical), white noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 31. Measured SNR vs. frequency curves (typical) at BER=10-3 - 72 kHz channel . . . . . . . . . 35
Figure 32. Measured SNR vs. frequency curves (typical) at BER=10-3 - 86 kHz channel . . . . . . . . . 35
Figure 33. PCB copper dissipating area for the ST7538Q dual channel reference design . . . . . . . . . 36
Figure 34. Packet-fragmented transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Figure 35. Thermal impedance typical curve for the ST7538Q mounted on the reference design
board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Figure 36. A recommended oscillator section layout for noise shielding . . . . . . . . . . . . . . . . . . . . . . . 38