Answer: The FT232RL is the SSOP-28 version of FTDI’s FT232R USB-to-UART bridge. Its internal 12 MHz oscillator needs VCC 4.0–5.25 V, so in practice it runs from USB 5 V. A separate VCCIO pin (1.8–5.25 V) sets the UART logic level. The on-chip 3V3OUT regulator can supply up to 50 mA to external logic. The UART runs to 3 Mbaud, and five CBUS pins are set in the internal EEPROM, which ships with VID 0403h / PID 6001h. (FTDI FT232R Datasheet v2.16, §3, §5, §8.)
Key specifications
| Parameter | Value | Condition | Source |
|---|---|---|---|
| Package | SSOP-28 (FT232RL); QFN-32 is FT232RQ | — | §1.2 p.3 |
| VCC (core) | 4.0–5.25 V | Internal oscillator | Table 5.2 p.15 |
| VCC (core) | 3.3–5.25 V | External crystal/oscillator | Table 5.2 p.15 |
| VCCIO | 1.8–5.25 V | UART and CBUS pins | Table 5.2 p.15 |
| Supply current | 15 mA typ (normal); 50/70/100 µA (USB suspend) | — | Table 5.2 p.15 |
| 3V3OUT | 3.0 / 3.3 / 3.6 V; up to 50 mA for external logic | Decouple with 100 nF | Table 5.2 p.15; Table 3.2 p.7 |
| Baud rate | 183 baud to 3 Mbaud | — | §4.2 Baud Rate Generator, p.14 |
| Output levels (VCCIO = 3.3 V) | VOH ≥ 2.2 V at 1 mA; VOL 0.5 V max at 2 mA | Standard drive | Table 5.4 p.16 |
| Output levels (VCCIO = 5.0 V) | VOH ≥ 3.2 V at 2 mA; VOL 0.6 V max at 2 mA | Standard drive | Table 5.3 p.15 |
| Absolute maximum | VCC −0.5 to +6.00 V; USBDP/USBDM −0.5 to +3.8 V; 500 mW at 5.25 V | — | Table 5.1 p.15 |
| Internal clock | 11.98 / 12.00 / 12.02 MHz (±1667 ppm) | — | Table 5.14 p.17 |
| Thermal (FT232RL) | θJA 55.82 °C/W; θJC 24.04 °C/W | Still air | Table 5.16 p.18 |
| Default USB IDs | VID 0403h, PID 6001h; unique serial programmed at final test | Factory EEPROM | Table 8.1 p.30 |
| Operating temperature | −40 to +85 °C | Power applied | Table 5.1 p.15 |
Pinout (SSOP-28)
| Pin | Name | Pin | Name |
|---|---|---|---|
| 1 | TXD | 15 | USBDP |
| 2 | DTR# | 16 | USBDM |
| 3 | RTS# | 17 | 3V3OUT |
| 4 | VCCIO | 18 | GND |
| 5 | RXD | 19 | RESET# |
| 6 | RI# | 20 | VCC |
| 7 | GND | 21 | GND |
| 8 | NC | 22 | CBUS1 |
| 9 | DSR# | 23 | CBUS0 |
| 10 | DCD# | 24 | NC |
| 11 | CTS# | 25 | AGND |
| 12 | CBUS4 | 26 | TEST |
| 13 | CBUS2 | 27 | OSCI |
| 14 | CBUS3 | 28 | OSCO |
(Tables 3.1–3.4, pp.7–8. USBDP already contains its series resistor and the 1.5 kΩ pull-up, so leave out external ones.)
Choosing the I/O level with VCCIO
| Target logic | VCCIO connection (Table 3.2) |
|---|---|
| 3.3 V MCU | Tie VCCIO to 3V3OUT (pin 17) |
| 5 V MCU | Tie VCCIO to VCC |
| 1.8–2.8 V MCU | External regulator fed from the same source as VCC (USB 5 V in bus-powered designs) |
3V3OUT budget: the LDO’s main job is powering the USB transceiver, but it can source up to 50 mA for external circuitry. A 3.3 V MCU drawing 30 mA plus a 2 mA LED leaves 18 mA of margin. Anything larger needs its own regulator.
Factory CBUS functions (Table 8.1)
| Pin | Default | Note |
|---|---|---|
| CBUS0 (23) | TXLED# | Drives a TX LED |
| CBUS1 (22) | RXLED# | Drives an RX LED |
| CBUS2 (13) | TXDEN | RS485 transmit enable |
| CBUS3 (14) | PWREN# | Low after enumeration, high in suspend; use a 10 kΩ pull-up |
| CBUS4 (12) | SLEEP# | Low in USB suspend |
Running the core at 3.3 V
The internal oscillator needs VCC ≥ 4.0 V. To run at 3.3 V, the datasheet (§7.6, p.29) gives this order:
- Power the chip first with VCC above 4.0 V.
- Set the EEPROM to use the external oscillator.
- Switch VCC to 3.3 V with an external oscillator fitted.
If the internal oscillator is disabled and no external oscillator is connected, the chip will not run. The two FTDI documents describe step 2 differently. Datasheet v2.16 §7.6 says FT_PROG cannot make the change and a custom application is needed. AN_100 v1.2 §3.1 shows a “Use External Oscillator” checkbox in FT_Prog. Test with the FT_Prog version you actually use.
Pitfalls specific to FT232RL
- Leaving TEST (pin 26) floating. It must be tied to GND, or the device “will appear to fail” (Table 3.3).
- Expecting 3.3 V operation without an external clock. With the internal oscillator, VCC must be at least 4.0 V.
- Powering a 1.8–2.8 V VCCIO from an unrelated rail. That supply must come from the same source as VCC.
- Running a whole board off 3V3OUT. It is rated for 50 mA of external load.
Part numbers (information only)
| Ordering code | Package / packing (§1.2) |
|---|---|
| FT232RL-Reel | SSOP-28, tape and reel, 2,000 pcs |
| FT232RL-Tube | SSOP-28, tube, 47 pcs |
| FT232RQ-xxxx | QFN-32 (different page) |
FAQ
- Can the FT232RL run from 3.3 V? The core (VCC) needs 4.0 V minimum with the internal oscillator. 3.3 V works only after the EEPROM is set for an external oscillator and one is fitted. The UART level can be 3.3 V at any time through VCCIO.
- What is the FT232RL default VID/PID? 0403h / 6001h, with a unique serial number programmed at final test.
- How much current can 3V3OUT supply? Up to 50 mA for external circuitry.
- What is the maximum FT232RL baud rate? 3 Mbaud. Non-standard rates down to 183 baud are generated by a fractional divider.
- What do the CBUS pins do by default? CBUS0 TXLED#, CBUS1 RXLED#, CBUS2 TXDEN, CBUS3 PWREN#, CBUS4 SLEEP#. All are reconfigurable in the EEPROM.
Related (internal links)
- CH340G alternatives: CH340C, CH340E, CP2102, FT232RL
- CH340 selector
- Silicon Labs CP2102
- WCH CH340G
- USB-UART bridges
Sources (retrieved 2026-10-26)
- FTDI, FT232R USB UART IC Datasheet, Version 2.16 (Document No. FT_000053): https://ftdichip.com/wp-content/uploads/2020/08/DS_FT232R.pdf
- FTDI, AN_100 Using the FT232R/FT245R with an External Crystal or Oscillator, Version 1.2: https://ftdichip.com/wp-content/uploads/2020/08/AN_100_Using_The_FT232_245R_With_External_OscFT_000067.pdf
Disclaimer
Values are copied from FTDI FT232R Datasheet v2.16 and AN_100 v1.2, read on 26 Oct 2026. Validate on your own hardware.
Reviewed by: Jasper · Updated: 2026-10-26