I use this FTDI USB to TTL Adapter: FT232RL It has a switch to select 5 Volts or 3.3 Volts as the logic level.This adapter I use mainly to program ESP8266 (switch set to 3.3). It works pretty well.
VCCIO+1.8V to +5.25V supply to the UART Interface and CBUS group pins (1...3, 5, 6, 9...14, 22, 23). In USB bus powered designs connect this pin to 3V3OUT pin to drive out at +3.3V levels, or connect to VCC to drive out at 5V CMOS level. This pin can also be supplied with an external +1.8V to +2.8V supply in order to drive outputs at lower levels.