FT232RL USB-to-UART bridge pinout

FT232RL is the SSOP-28 version of the FT232R bridge. It integrates the USB transceiver, internal clock and EEPROM and has a separate VCCIO supply.

SSOP-28

28 contacts Current package

FTDI · 5.3 mm nominal body width · 0.65 mm lead pitch

SSOP-28 pinout

Top view. Match pin 1 to the package mark. The numbers advance counterclockwise.

Selected pin details

27 · OSCI

Input · Clock inputs / oscillator

External 12 MHz oscillator input. Leave open when using the internal oscillator.

FTDI FT_000053, version 2.12, §3.2

Electrical limits · Link to this pin

All 28 pins

Pin	Signal	Direction	Function
1	TXD Output	Output	Asynchronous transmit. Connect to the receiver of the external logic-level UART.
2	DTR# Output	Output	Data Terminal Ready, active low.
3	RTS# Output	Output	Request to Send, active low.
4	VCCIO Supply input	Supply input	Sets the UART and configurable pin logic levels.
5	RXD Input	Input	Asynchronous receive. Connect to the transmitter of the external logic-level UART.
6	RI# Input	Input	Ring Indicator, active low.
7	GND Return	Return	Connect to the circuit ground plane.
8	NC Unconnected	Unconnected	Leave open for this circuit.
9	DSR# Input	Input	Data Set Ready, active low.
10	DCD# Input	Input	Data Carrier Detect, active low.
11	CTS# Input	Input	Clear to Send, active low.
12	CBUS4 Configurable output	Configurable output	EEPROM-configurable output. The factory function is SLEEP#.
13	CBUS2 Configurable	Configurable	The internal EEPROM selects the function. See the CBUS options table for available configurations.
14	CBUS3 Configurable	Configurable	The internal EEPROM selects the function. See the CBUS options table for available configurations.
15	USBDP Bidirectional	Bidirectional	USB D+ line. Route with the other data line as a differential pair and use the manufacturer’s reference circuit.
16	USBDM Bidirectional	Bidirectional	USB D− line. Route with the other data line as a differential pair and use the manufacturer’s reference circuit.
17	3V3OUT Regulator output	Regulator output	Nominal 3.3 V regulator output. Bypass to ground with 100 nF.
18	GND Return	Return	Connect to the circuit ground plane.
19	RESET# Input	Input	Active-low reset. The internal power-on reset handles a normal bus-powered start.
20	VCC Supply input	Supply input	Main supply input. Connect to the specified operating rail and decouple locally.
21	GND Return	Return	Connect to the circuit ground plane.
22	CBUS1 Configurable	Configurable	The internal EEPROM selects the function. See the CBUS options table for available configurations.
23	CBUS0 Configurable	Configurable	The internal EEPROM selects the function. See the CBUS options table for available configurations.
24	NC Unconnected	Unconnected	Leave open for this circuit.
25	AGND Return	Return	Connect to the ground plane with the other return leads.
26	TEST Input	Input	Tie to ground for normal operation.
27	OSCI Input	Input	External 12 MHz oscillator input. Leave open when using the internal oscillator.
28	OSCO Output	Output	External 12 MHz oscillator output. Leave open when using the internal oscillator.

Signal assignments

USB data pair

Keep the D+ and D− polarity consistent at the connector and the bridge. Use the package-specific application circuit for matching and bypass components.

Asynchronous UART

Use the receive and transmit pair with a common ground. The signals use logic-level voltages. A separate transceiver is needed for bipolar RS-232.

Electrical limits

Parameter	Limit	Conditions and source
VCC with internal oscillator4.0–5.25 V	4.0–5.25 V	Use the 5 V VBUS circuit. Refer to §7.6 for operation with an external oscillator and a lower supply. FTDI FT_000053, version 2.12, §3.2 note 1
VCCIO1.8–5.25 V	1.8–5.25 V	Set this rail to suit the connected UART logic. The guide uses the internal 3.3 V output. FTDI FT_000053, version 2.12, Table 3.2

Models and documents

The interactive map covers FT232RL in SSOP-28. FT232RQ in QFN-32 has different pin numbers. Use the FT232R datasheet §3.3 for that package.

FT232RL: 5.3 mm nominal body width · 0.65 mm lead pitch

FTDI FT232R datasheet· FT_000053 v2.12, §3.2 and Figs. 6.1 and 6.4.
FTDI FT232RL product documentation· Ordering options, errata and migration documents.