SN65HVD1787: Sn65hvd1787

The TIDA-00527 reference design has just low-pass filters between the bus lines and its supply rails, so it works only with 5 V. (Same on the THVD8000EVM.)

You would have to create your own board and insert a voltage regulator.

Hi Hanstar,

So all of our RS-485 based power line communication designs are going to be limited to a max supply of 5V - so there would need to be a voltage regulator that bucks the 24V down to 5V. In general the RS-485 based power line communication devices are intended to send data to another RS-485 device across a shared bus - so it wouldn't be able to directly control the LEDs (the data would have to go through a controller/ LED driver to actually control the LED's most likely). 

That being said - if that use case sounds like it will still fit for your specific application I do have a few notes.

1. TIDA-00527 is outdated and we really don't suggest people use it anymore as the tradeoffs on the design are significant (special encoding required, very large passive elements, not flexible in design (our guide gives no indication how to adapt that design) - the design has been replaced with the THVD80x0 family of devices for PLC communication

2. THVD8000 or THVD8010 (depending on needed data rate - THVD8000 can support up to 500kbps (possibly up to 1Mbps at the cost of Duty cycle distortion exceeding +/-2% (could possibly double to +/-4%) and THVD8010 can support up to 30kbps - but neither require special encoding on the datastream so there aren't as many throughput reductions as with old TIDA-00527).

THVD80x0 uses on off keying (OOK) modulation but retains a similar architecture to TIDA-00527 (basically same design but using THVD80x0 instead and usually can have much smaller passive components). OOK with the THVD80x0 converts a single ended logic high signal into a 0V differential signal while a single ended logic low signal is converted into a pulse train of frequency F_mod (which is selected via a resistor on the F_SET pin of the THVD80x0 devices) F_mod >= 10*data_rate.  

As an example in a point-to-point THVD8000 system - the RS-485 device does not actually control the power:

Power and data just share the same bus. This is the same in the TIDA-00527 as well. 

With all that being said a few resources if this part seems like it may be able to help you:

1. THVD8000 Datasheet -> this datasheet gives all the design information necessary to create a shared DC + data bus. Generally up to 36V (but up to 50V usually isn't issue for standard design - if proper bus loading can be met)  

2. THVD8010 Datasheet -> This is a very similar device; it is slower than THVD8000 but has a larger hysteresis curve so can handle noisy environments better. 

3. THVD8000 Design Guide -> The information in here applies to all THVD80x0 devices as well - but we just titled it the THVD8000 design guide. It gives a bit more information on design principles

Those three are the most important documents - but to help show the flexibility of this part please also see the following two notes:

4. THVD80x0 Low Voltage AC implementations (<=36VAC @ 50Hz - 60Hz)  - > This explains deviations from standard design to support AC powerlines

5. THVD80x0 Low Bus Impedance and/or High Voltage Implementations - generally with applications < 50V we don't see this type of implementation use - but because RS-485 has a bus loading requirement that is strict (Impedance seen from "A" or "B" to GND is no less than 375 Ohms(for analysis termination is open circuited - however should be included in actual design) and the impedance seen from "A" to "B" (considering terminated system) is no less than 54 ohms) sometimes the overall system can't meet those needs so a more robust system design needs to be used. 

Please let me know if you have any other questions - but in conclusion:

1. RS-485 based Power Line Communication requires a 3V to 5.5V supply for the transceiver - above that and damaged IC's are possible - we suggest THVD80x0 family of devices for RS-485 based Power line communication.

2. RS-485 based Power Line Communication IC's do not control the power the directly - its essentially sharing a bus with the data signal being much higher frequency than power signal allowing for easy coupling/decoupling - the THVD80x0 allows for smaller passive components and no special encoding would be required. 

Best,

Parker Dodson