component

CP2104

Public Made by Adom

by adom

Silicon Labs USB-to-UART bridge, QFN-24. USB 2.0 full-speed, up to 2 Mbps, integrated EEPROM + clock + regulator. Datasheet-verified.

componentinterfaceusb-uartusb-bridgevirtual-com-portqfn-24silicon-labs
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3D Model

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Symbol & Footprint

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Datasheet

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Contents

README

markdown

CP2104

Silicon Labs · USB-to-UART bridge · QFN-24

Turns a USB port into a serial UART so a host sees a virtual COM port and the board gets TXD/RXD plus modem control lines. It handles USB 2.0 full-speed and UART rates up to 2 Mbps, and integrates the oscillator, voltage regulator, and a configurable EEPROM for the USB descriptors, so the external parts are just decoupling. Four GPIO pins add status LEDs or control. A compact, self-contained alternative to the FT232 and CH340 for USB serial.

Pinout

Pin Name Type Function
1 RI input Ring Indicator control input (active low). Modem-status handshake line.
2 GND power_in Ground reference. Must be tied to ground.
3 D+ bidirectional USB D+ full-speed (12 Mbps) differential data line. Connect to the USB connector D+ pin.
4 D- bidirectional USB D- full-speed (12 Mbps) differential data line. Connect to the USB connector D- pin.
5 VIO power_in I/O supply voltage input. Sets digital I/O rail from 1.8 V up to VDD. Decouple to GND.
6 VDD power_in Digital core supply (3.0 to 3.6 V). Also the output of the on-chip 3.45 V voltage regulator when REGIN is driven from VBUS (self- or USB-powered). Decouple to GND.
7 REGIN power_in 5 V regulator input (3.0 to 5.25 V). Input to the on-chip 3.45 V LDO whose output appears on VDD. Typically tied to VBUS.
8 VBUS input VBUS sense input. Connect to the VBUS signal of the USB connector so the device can detect bus attach (2.5 V threshold).
9 RST bidirectional Device reset (active low). Open-drain output of internal POR / VDD monitor; may also be driven low externally for at least 15 us to initiate a system reset.
10 NC unconnected No connect. Leave floating or tie to VIO.
11 GPIO.3 bidirectional User-configurable digital I/O. Supply is VIO (1.8 V to VDD). May be left unconnected when unused.
12 GPIO.2 bidirectional User-configurable digital I/O; optional RS-485 transceiver bus-control output (Section 7.2). Supply is VIO.
13 GPIO.1 bidirectional User-configurable digital I/O; optional receive-toggle output (Section 7.1). Supply is VIO.
14 GPIO.0 bidirectional User-configurable digital I/O; optional transmit-toggle output (Section 7.1). Supply is VIO.
15 SUSPEND output Active-low USB suspend indicator. Driven low while the CP2104 is in the USB Suspend state.
16 VPP passive OTP ROM programming supply pin. Connect a 4.7 uF capacitor between this pin and ground to support ROM programming via the USB interface. During programming VPP is 5.75 V to VIO+3.6 V.
17 SUSPEND output Active-high USB suspend indicator. Driven high while the CP2104 is in the USB Suspend state.
18 CTS input Clear-To-Send hardware flow-control input (active low). Modem handshake line.
19 RTS output Request-To-Send hardware flow-control output (active low). Modem handshake line.
20 RXD input Asynchronous UART receive data input. Data rates 300 bps to 2 Mbps; 5/6/7/8 data bits; 1/1.5/2 stop bits; odd/even/mark/space/no parity.
21 TXD output Asynchronous UART transmit data output. Data rates 300 bps to 2 Mbps; 5/6/7/8 data bits; 1/1.5/2 stop bits; odd/even/mark/space/no parity.
22 DSR input Data-Set-Ready modem control input (active low).
23 DTR output Data-Terminal-Ready modem control output (active low).
24 DCD input Data-Carrier-Detect modem control input (active low).

Key specifications

Parameter Value
Type USB-to-UART bridge
USB USB 2.0 full-speed
UART data rate 300 bps to 2 Mbps
GPIO 4 configurable
Integrated Oscillator, regulator, EEPROM
Supply VBUS or self-powered (3.0-3.6 V core)
Package QFN-24 (4x4 mm)

Ordering variants

Same part, different packaging or reel option.

  • CP2104-F03-GM (QFN-24)
  • CP2104-F03-GMR (QFN-24, tape & reel)

CAD (KiCad official)

  • Symbol: Interface_USB:CP2104 (KiCad official)
  • Footprint: Package_DFN_QFN:QFN-24-1EP_4x4mm_P0.5mm_EP2.6x2.6mm
  • 3D model: QFN-24 (KiCad packages3D, STEP)
  • 3D model files: cp2104-etched.step / cp2104-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); cp2104.step / cp2104.glb are the bare package body.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Silicon Labs datasheet (22 pp, sha256 9569257991f26467, retrieved 2026-08-17, tier: manufacturer)
  • Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF