MAX3232 +-3.3 V output

Hi,

I have a small rotation mount that I can controll via a +-3.3 V RS232 interface. I would like to connect it to the 5V-TTL TX/RX port of an Arduino Micro. I often read that MAX3232 should do the conversion. However, I am a bit confused after reading the datasheet.

If I set Vcc to 3.3 V the output voltage should be typically 3.2 V according to the electrical characteristics on page 2. But on page 4 and 5 are figures that show an output of 5.5 V for Vcc=3.3V. Also, the description tells me that the output should be 5.5 V independent of Vcc.

Is this IC suitable for my application? How do I force it to 3.3 V? Any other suggestions? Thanks!

I have a small rotation mount that I can controll via a ±3.3 V RS232 interface.

Are you sure that your mount wants an RS232 signal at +/-3.3V? RS232 levels are normally higher than that. The datasheet says that the device outputs RS232 signals at typically +/-5.4V.

If I set Vcc to 3.3 V the output voltage should be typically 3.2 V according to the electrical characteristics on page 2.

Are you referring to the Absolute Maximum Ratings on the top left of the page? The datasheet says that T_OUT is +/-13.2V - the ‘1’ is easy to miss at a quick glance.

I think it would be easier to understand your question if you were to be more specific when talking about “output”, as there are the RS-232 side outputs and the TTL side outputs.

There isn't really something like a 3.3V RS232 interface. Levels are usually a lot higher -3V .. -15V for a logic 1, +3V .. +15V for a logic 0.

Can you post a link tot the datasheet of the "small rotation mount".