CH340 UART TTL adapter voltage too high?

Hardware
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1

Would 3.8V be too much for uart pins? I expect so, but thought I would ask anyway, in case I am missing something…

I got a CH340 (maybe actually CH340G) UART TTL module to use with a Le Potato and a Tritium. The Amazon description says 3.3V and 5V modes, but when I tested it, before using it on the boards, its 3.3V mode gave 3.8V. I found another seller which listed 3.3V mode having a range of 3.3-3.8V. I am thinking of returning it due to the description not including the full range and getting another CP2102, instead. (I have one I am using on another board.)

I had heard good things about CH340, and I wanted a different kind in case I find myself in a situation where the CP2102 had some issue. What kinds do you recommend?

This CH340 works fine at about 5V and 3.3-3.8V, but I hesitate to use it with these boards when it can go that much over 3.3V, unless I find they can handle it.

Thanks for any advice.

2

I do believe the gpio input is generally 3.3 -+0.3. If you are relying on the chip to drop 3.3 into the board you may want to use the other chip or maybe have a resistor inline to take the edge off

3

Usually it is current that kills GPIOs and not unloaded voltage. Many UARTs are OD (open drain) and can work with either 3.3V or 5V but most SBC GPIOs for UART are not OD.

4

Thanks. I’m thinking maybe I will just use the uart-a overlays for these, hooking those pins to each others’ uart terminal headers as needed.