12V signal Vin also decreses when it is connected Step-down Voltage regulator D24V3F3

I purchased D24V3F3 lately and my purpose was getting lowered signal (3.3V) Vout from original signal (Vin 12V)
But after wiring I found a problem that Vin also decreases to 2.4V. This happened when the Vin is from K-line signal (12V)
On the other hand, when I connected 12V to Vin of this step-down Voltage regulator from a POWER SUPPLY, it works well (Vout is 3.3V and it goes to 0 when Vin goes to 0)

So I assume that this device is not suitable for lowering communication signal like K-line. But want to ask if I did some mistake.
Anyone who knows about this or has experience like me please let me know.


Step-down regulators like ours are meant to reduce the voltage of a DC power source, not a varying communications signal. I am not familiar with the K-line protocol, so I cannot say for sure, but a level shifter might be more appropriate for something like that. It looks like K-line communication is used in automotive applications, so you might try asking for help on a forum specializing in automotive electronics.


Thanks a lot for your reply! Yes K-line (ISO 9141) is a communication protocol used in Automotive.
I should try Level shifter as you mentioned.

I purchased LLS #2595 and was able to have lower level signal from K-line successfully. It was fun to use. :slight_smile:

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