Hello Team
My customer is working on TSS521 for the water meter application and has below question. Could you please help?
Please see attached the schematics of TSS521. The Figure 8 on the TSS521 datasheet, they use the same connection for "Connection Schematics for the Remote Supply with Battery Support". They are able to receive the message coming from the master side, but they are not able to send the message to MBUS line. According to the datasheet and the MBUS standard, the message should be transmitted with the current modulated and the line should provide 11-20 mA current on Logic 0 state. There is an Rris resistance on the schematics to adjust this current. According to the Figure 3 , they used 100 Ohm resistance and they are only able to get only 800uA current instead of getting 15 ma current from the line. There is a regulator in TSS521 and this IC can use 3.3V supply from this regulator, but they measure 2.6V voltage. Do you think that the issue explained above is related to this supply voltage? They tried VCTC as 10uF, 22uF, 220uF and 330uF but no changing. Vstc pin voltage is around 3.9V. They think that this voltage should be around 5.6 - 6.4V voltage range from the "Electrical Characteristics" in the datasheet.
Could you please check their schematics and help us how to fix this issue?
Best Regards
Yunus
