Max DC voltage X-NUCLEO-PLM01A1 can communicate over ?

[JARViE]

What's the max DC powerline voltage I can use with the X-NUCLEO-PLM01A1 expansion board?  Asked another way, what's the max voltage I can connect to the PLM_CONNECTOR C1?

[Peter BENSCH]

Welcome @JARViE, to the community!

With the appropriate design of the networks at PA_OUT and RX_IN, any DC voltage is conceivable in principle.

However, with the current configuration of the X-NUCLEO-PLM01A1, the DC voltage is determined by the voltage rating of C2 and, even more so, by the breakdown voltage of D4. The maximum DC voltage is not specified for reasons unknown, but I suspect that it may be max 10..12V without exceeding the maximum power dissipation of R5.

Hope that helps?

Regards
/Peter

[JARViE]

Thanks Peter, that's helpful and makes sense.

One additional thing to note, for the DC supply generating the power line to stay voltage compliant (i.e. maintain its set voltage and not enter constant-current mode) the supply must source enough current to the X-NUCLEO-PLM01A1 PLM_CONNECTOR to overcome the input impedance of its analog front-end.  At DC, the input impedance of the PLM01A1 front-end looks like 150 Ohms.  So, the DC supply needs to be able to source a minimum current of I = V / 150 Ohms, where V is the voltage set point of the supply.  Two PLM01A1 boards look like a load of 75 Ohms on the line (150 || 150), so the supply needs to be able to source a minimum current of I = V / 75 Ohms.  In general, the supply needs to source a minimum current of,

                             I = V / (150 / N), where V = supply set voltage, N = number of PLM01A1 boards