FT232RL-2000 FTDI [Future Technology Devices International Ltd.], FT232RL-2000 Datasheet - Page 32

• Manufacturer Part Number: FT232RL-2000
• Description: USB UART IC - Single chip USB to asynchronous serial data transfer interface
• Manufacturer: FTDI [Future Technology Devices International Ltd.]

7.6 Using the External Oscillator
The FT232R defaults to operating using its own internal oscillator. This requires that the device is
powered with VCC(min)=+4.0V. This supply voltage can be taken from the USB VBUS. Applications which
require using an external oscillator, VCC= +3.3V, must do so in the following order:
The FT232R will fail to operate when the internal oscillator has been disabled, but no external oscillator
has been connected.
1. When device powered for the very first time, it must have VCC > +4.0V. This supply is available
2. The EEPROM must then be programmed to enable external oscillator. This EEPROM modification
3. The FT232R can then be powered from VCC=+3.3V and an external oscillator. This can be done
from the USB VBUS supply = +5.0V.
cannot be done using the FTDI programming utility, MPROG. The EEPROM can only be re-
configured from a custom application. Please refer to the following applications note on how to do
this:
http://www.ftdichip.com/Documents/AppNotes/AN_100_Using_The_FT232_245R_With_External_
Osc(FT_000067).pdf
using a link to switch the VCC supply.
Copyright © 2010 Future Technology Devices International Limited
FT232R USB UART IC Datasheet Version 2.07
Document No.: FT_000053
Clearance No.: FTDI# 38
32