Получил ответ из support'а, Спрашивал, могу ли я использовать их драйвер для передачи на скорости 19200, ответили вот что:
Yes there is not a minimum data rate and it will work fine at 19200 bps.
Perhaps we should add a statement on the datasheet to say that but that is why we say " The controlled slew rate limits the
data rate to 500 kbps. "
This means that it will not work at faster (or greater) than 500 kbps but is ok at any data rate below this.соответственно радуемся и пользуем