Force download and charset

Hello community

I'm fetching data from the database and create a CSV text file. I'd like to force download that file. With the download helper this works like a charm. The problem is, that die CSV file is encoded with UTF-8 (like the database). I needed the downloaded file to be encoded for ISO Latin 1.

Is there a way to change the charset when using force_download() or do I have to create a download function on my own?

Thanks for your help!