USB-RS232 converter (FT231X BoB) - Bare PCB (180537-1)

In 2011 we published a small PCB, FT232R USB/Serial Bridge/BOB (110553) with a USB-UART IC from FTDI, the FT232RQ. Here we present its successor with a cheaper version, an FT231XQ.

But there are some other changes too. Instead of connectors, alongside the PCB, normal pin headers are used that are mounted on the bottom side and make the PCB a little smaller when mounted, compared to the old BoB. An ESD protection device (D1) is added in the USB data signal lines for extra safety.

Despite less room for all parts to fit on the PCB, it is only a little over 2 mm longer. The FT231 has four configurable CBUS I/O pins, one less now. More importantly, however, the power supply for the I/O's VCCIO is only specified for +1.8 V to +3.3 but is 5 V tolerant for external UART logic running on +5 V. The +3.3 V internal regulator of the FT231 can deliver 50 mA to external circuitry.

The manufacturer FTDI has a utility to configure several settings, FTPROG. Such as the function of the CBUS pins. By default, CBUS1 and CBUS 2 are low-level outputs to drive receive and transmit LEDs, indicating data transfer on the USB bus. So, when receiving data through the UART, the TX LED lights up. If you prefer this the other way around, FTPROG can be used to change this. But be careful the chip can become unresponsive when wrong settings are programmed.

Some of the more important properties of the new BoB:

• Micro-USB connector USB 2.0
• Full Speed capable VCCIO +1.8...+3.3 V (max. 4 V, 5 V input from UART logic tolerant) +3.3 V regulator output, max. 50 mA
• Data transfer 300 baud to 3 Mbaud
• UART Compatible with RS232, RS485, and RS422
• I/O pin output drive 4 mA - 16 mA
• 4 configurable CBUS pins

Here you can find information regarding the EEPROM Programming Utility, the VCP Drivers and the D2XX Drivers