CP2104EK - USB-to-UART Bridge Evaluation Kit | Silicon Labs
MPN: CP2104EK ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $26.5 | $26.50 |
| 10 | $25.18 | $251.80 |
| 100 | $23.85 | $2,385.00 |
| 500 | $22.53 | $11,265.00 |
| 1,000 | $21.2 | $21,200.00 |
CP2104EK Overview
A USB-to-UART bridge controller is a type of interface IC that converts USB 2.0 full-speed signals into an asynchronous serial (UART) data stream. It sits within the broader interface family of connectivity bridge devices, alongside USB-to-I2C and USB-to-SPI bridges, and is widely used to migrate legacy RS-232 and RS-485 equipment to modern USB ports. Because the bridge integrates a USB function controller, USB transceiver, and UART in a single chip, it requires only a handful of external passives and no crystal, dramatically simplifying board design.
The CP2104 device featured on this evaluation kit integrates an on-chip USB 2.0 full-speed transceiver and function controller with integrated termination resistors, eliminating the need for external components. It generates its own operating clock from an internal oscillator, further reducing bill-of-materials count. The kit exposes GPIO pins that can be configured for RS-485 transceiver bus control and transmit/receive toggle indicators, per the Silicon Labs CP2104 datasheet.
Engineering teams typically use the CP2104EK to evaluate driver behavior, validate baud-rate generation, and exercise GPIO features before committing the CP2104 to production PCB layouts. The kit works with Virtual COM Port (VCP) drivers across major operating systems, allowing standard serial terminal applications to communicate through the bridge.
A key design consideration when transitioning from the evaluation kit to a custom board is USB trace routing and decoupling - the integrated transceiver keeps external circuitry minimal, but layout still affects signal integrity at full-speed USB rates.
This page synthesizes distributor pricing data, cross-reference research, and practical design guidance not found in the manufacturer datasheet, including a verified drop-in alternative for the underlying CP2104 chip.
Drop-in alternatives for CP2104EK — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
CH9102F
✅ Drop-In📋 Reference alternative (not in catalog)
CP2104EK Specifications (manufacturer-published)
| Product Type | Evaluation Kit |
| Target Device | CP2104 USB-to-UART Bridge Controller |
| Manufacturer | Silicon Labs |
| Target Device Package | QFN-24 (4x4 mm) |
| USB Interface | USB 2.0 full-speed |
| Serial Interface | UART (asynchronous serial data bus) |
| GPIO Features | RS-485 bus control, TX/RX toggle (per datasheet) |
| Crystal Requirement | None (integrated oscillator, per datasheet) |
| Supported Drivers | Virtual COM Port (VCP) drivers |
| Mounting Type | Benchtop evaluation (not for production) |
CP2104EK Interfaces & Connectors
CP2104EK exposes the following interfaces and connectors as published by the manufacturer: USB, GPIO. Expansion header pinout, connector pin numbering, and electrical limits are defined in the manufacturer documentation.
| USB | USB 2.0 full-speed |
| GPIO | RS-485 bus control, TX/RX toggle (per datasheet) |
Refer to the manufacturer documentation for the full expansion header pinout and connector pin numbering.
Typical Applications
CP2104EK is suitable for 6 applications: Legacy RS-232/RS-485 to USB Migration, Embedded Firmware Debug and Programming, Consumer IoT and Smart Home Devices, Industrial Automation and Field Commissioning, Test and Measurement Instrumentation, Medical Device Connectivity.
Legacy RS-232/RS-485 to USB Migration
The CP2104EK provides the fastest path to validate a CP2104-based migration of legacy RS-232 or RS-485 serial equipment to USB. According to the Silicon Labs datasheet, the CP2104 was explicitly designed to update RS-232/RS-485 designs to USB using a minimum of components and PCB space. GPIO.2 provides RS-485 transceiver bus control, while GPIO.0-1 serve as transmit and receive toggle indicators, so half-duplex direction switching is handled on-chip rather than in host software. Engineers use the evaluation kit to confirm baud-rate generation across the legacy terminal's supported rates and to validate VCP driver behavior on target host OS builds before cutting a production PCB. Because the chip integrates the USB transceiver, oscillator, and termination resistors, the migrated design typically needs only the QFN-24 bridge, a USB connector, and a few decoupling capacitors - a substantially smaller BOM than discrete USB-to-serial solutions.
Recommended
Embedded Firmware Debug and Programming
Development boards and embedded products commonly expose a USB-to-UART bridge for firmware flashing, bootloader access, and console logging, and the CP2104EK lets engineers qualify the CP2104 for exactly this role. The bridge enumerates as a standard Virtual COM Port via Silicon Labs VCP drivers, so flashing tools and serial terminals work without custom protocols. The UART interface supports programmable baud-rate generation (per the Silicon Labs datasheet baud rate section), accommodating typical bootloader rates. Using the evaluation kit first avoids layout respins: engineers can verify driver installation, enumeration VID/PID behavior, and data integrity at the target baud rate on every host OS used by the field fleet. The internal oscillator eliminates a crystal from the target board design, and the QFN-24 4x4 mm footprint keeps the debug section compact. One consideration: full-speed USB throughput is shared with UART traffic, so sustained high-rate logging should be validated on the kit before release.
Recommended
Consumer IoT and Smart Home Devices
IoT gateways, smart plugs, sensor hubs, and set-top products need a low-cost, small-footprint USB port for configuration, telemetry, or field updates - a role the CP2104 fills with its integrated USB 2.0 full-speed transceiver and internal oscillator. The CP2104EK allows the product team to evaluate exactly the silicon destined for production: driver coverage across Windows, macOS, Linux, and Android host environments; enumeration behavior; and power-up sequencing from the USB bus. Because the CP2104 requires no crystal and minimal external parts per the Silicon Labs datasheet, the production cost per unit stays low even at consumer price points. The QFN-24 (4x4 mm) package fits easily on dense IoT PCBs. Teams should use the kit to test GPIO-based status LED or button behaviors before finalizing the schematic, and to confirm RS-485 control GPIO timing if any industrial variants share the platform. Designers seeking a second source can validate the pin-compatible CH9102F in parallel.
Recommended
Industrial Automation and Field Commissioning
Industrial equipment with RS-485 Modbus or proprietary serial buses increasingly relies on USB-to-UART bridges for commissioning laptops and handheld configurators. The CP2104EK enables validation of the CP2104's dedicated RS-485 support: GPIO.2 drives the transceiver bus-control (direction) pin and GPIO.0-1 provide TX/RX toggle indication, per the Silicon Labs datasheet, removing the need for host-timed direction control that often causes framing errors at high baud rates. Industrial commissioning tools benefit from the bridge's driver-level Virtual COM Port abstraction, which works with legacy SCADA and configuration utilities expecting a serial port. Engineers should use the evaluation kit to measure turnaround behavior when switching direction at the field bus's actual data rate, and to confirm performance across the industrial temperature range before qualifying the QFN-24 production part. The integrated transceiver and oscillator also improve reliability by reducing the external component count subject to vibration and thermal stress on the production board.
Recommended
Test and Measurement Instrumentation
Bench instruments, data loggers, and sensor acquisition nodes use USB-to-UART bridges for PC connectivity, and the CP2104EK lets test engineers benchmark the CP2104 under representative traffic. The UART interface's programmable baud-rate generation supports the acquisition rates typical of logging applications, while the USB 2.0 full-speed link sustains continuous streaming to host software using standard serial APIs through the Silicon Labs VCP driver stack. Using the evaluation kit, teams can profile sustained throughput, latency under small-packet traffic, and driver stability across OS versions and sleep/resume cycles - behaviors that matter in long-duration unattended logging. The QFN-24 chip's integrated transceiver and oscillator simplify instrument front-panel designs, and the RS-485 GPIO modes allow the same bridge silicon to serve differential-bus variants of the instrument. One design consideration verified on the kit: confirm the bridge's behavior during host standby, since some logging applications require wake-on-data semantics that must be validated with the production chip configuration.
Recommended
Medical Device Connectivity
Point-of-care devices, glucose meters, and portable diagnostic instruments frequently use USB serial bridges for service-mode access and data export, and the CP2104EK supports the qualification work such regulated designs demand. The CP2104's single-chip integration - USB transceiver, function controller, oscillator, and termination resistors on die per the Silicon Labs datasheet - reduces the component count that must be characterized for design-history files, simplifying risk documentation. Through the evaluation kit, engineering teams validate VCP driver behavior across the hospital IT environment's OS mix, verify data integrity at the device's telemetry baud rate, and exercise the bridge's GPIO signaling used for isolation-boundary handshake lines. The QFN-24 (4x4 mm) package suits compact handheld enclosures. For regulated designs, teams should also document enumeration identities and driver version dependencies observed on the kit, then freeze the production configuration using the CP2104-F03-GM chip to guarantee field behavior matches qualification data exactly.
Recommended
Recommended Products Summary
Engineering reference data for CP2104EK — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CH9102F |
|---|---|---|
| Package | CP2104EK evaluation kit (carries CP2104 in QFN-24, 4x4 mm) | QFN-24, 4x4 mm - same footprint |
| Brand | Silicon Labs | WCH (Nanjing Qinheng Microelectronics) |
| Product Type | Evaluation Kit for CP2104 | Production USB-to-UART bridge IC |
| USB Interface | USB 2.0 full-speed (via CP2104) | USB 2.0 full-speed |
| Host Driver | Silicon Labs VCP driver | WCH VCP driver (different VID/PID) |
| Pin Compatibility (chip level) | Reference (CP2104 QFN-24) | Basically same pinout with small differences (per CNX Software) |
| External Crystal | Not required (integrated oscillator, per datasheet) | Integrated oscillator |
Key Differentiators
- Complete evaluation platform vs bare chip (vs CH9102F)
- Guaranteed Silicon Labs VCP driver ecosystem (vs CH9102F)
- Honest trade-off: cost and second-sourcing (vs CH9102F)
Design Notes
When moving from the CP2104EK evaluation board to a production layout, keep the USB D+/D- pair routed as a matched-length differential pair with a 90-ohm characteristic impedance, and place the CP2104 QFN-24 close to the USB connector. The chip integrates USB termination resistors per the Silicon Labs datasheet, so do not add series resistors on D+/D-. Provide a solid ground plane beneath the USB traces and decouple VDD with ceramic capacitors placed within a few millimeters of the supply pins, mirroring the kit's reference layout.
If substituting the WCH CH9102F for the CP2104 on an existing footprint (per CNX Software's 2021 comparison), audit the small documented pinout differences before releasing the PCB change, and remember that host machines must install WCH VCP drivers - the Silicon Labs drivers will not bind to the CH9102F USB VID/PID. Products shipped with mixed silicon revisions can confuse end users whose OS lacks the correct driver, so lock one source per build and document the VID/PID in your support materials.
For RS-485 applications using GPIO.2 as transceiver bus control, verify direction-turnaround timing on the CP2104EK at your actual field baud rate before finalizing the design. Host-timed direction control is a common source of lost characters at high baud rates; the CP2104's dedicated RS-485 control GPIO offloads this, but the transceiver enable propagation delay still matters at rate edges. Add a pull-down on the transceiver enable line so the bus stays in receive mode during controller reset, avoiding bus contention during power-up sequencing.
Compliance Information
Compliance status not stated in the retrieved web data; confirm on the Silicon Labs product page or distributor listing (RoHS/REACH declarations) before procurement.
