XR21B1421IL28-F - USB 2.0 FS to UART Bridge IC | MaxLinear
N.º de pieza: XR21B1421IL28-F ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $6.8 | $6,80 |
| 10 | $6.12 | $61,20 |
| 100 | $5.44 | $544,00 |
| 500 | $4.89 | $2.445,00 |
| 1.000 | $4.35 | $4.350,00 |
XR21B1421IL28-F Descripción general
A USB-to-UART bridge is a category of interface controller IC that converts USB signaling into a serial UART data stream. Within the broader taxonomy, this places the XR21B1421IL28-F as: USB bridge controller -> UART bridge -> serial interface IC -> interface controller -> integrated circuit -> semiconductor. Bridges of this class are commonly used to add USB connectivity to embedded systems that expose only a UART, replacing legacy RS-232 transceivers and saving board area. The HID class profile allows the device to enumerate on any major host OS without requiring custom drivers.
Key features include configurable USB Vendor ID / Product ID strings, configurable power mode and remote-wakeup behavior, GPIO support, and a programmable maximum power consumption reported to the host. The integrated 3.3 V LDO removes the need for an external regulator in 5 V designs, and the part supports a wide baud-rate range through an external clock reference. Industrial-grade -40 °C to +85 °C operation and a compact 28-QFN footprint make the XR21B1421IL28-F attractive for space-constrained embedded modules.
Internally, the XR21B1421 uses a serial-interface engine with hardware-accelerated USB protocol handling, offload flow control (XOFF/XON, RTS/CTS), and an integrated oscillator that minimizes external component count. Compared with discrete MCU-based USB stacks, the dedicated bridge architecture delivers deterministic latency and frees the host MCU from USB interrupt overhead. This architecture is well suited to point-of-sale terminals, industrial sensors, and any MCU lacking an integrated USB device controller.
Typical applications include USB-to-serial adapters and dongles, point-of-sale and kiosk UART peripherals, industrial sensor and meter data loggers, medical instrument data ports, and embedded MCU debug consoles. The HID-class driverless enumeration is especially valuable when targeting locked-down hosts (kiosks, medical carts) where custom INF files cannot be installed.
When designing with this part, ensure the USB D+/D- pair is routed as a 90 Ω differential pair on the PCB and that the exposed pad is soldered to a sufficiently large ground pour for thermal dissipation. Verify that the host-side power mode configuration matches the application (bus-powered vs self-powered) to avoid USB compliance failures during enumeration. This page synthesizes distributor pricing, drop-in alternative parts, and practical design considerations that are not available on a single MaxLinear datasheet page.
Alternativas directas para XR21B1421IL28-F — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con XR21B1421IL28-F (mismo factor de forma y huella) — difiere en Operating Temperature, Supply Voltage.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
XR21B1421IL28
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
XR21B1421IL28TR-F
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
XR21B1421IL28-F Especificaciones
| Función | USB Bridge, USB to UART |
| Protocol | USB 2.0 Full-Speed (12 Mbps) |
| Interfaz | UART |
| Number of Channels | 1 |
| USB Class | HID (driverless enumeration) |
| Tensión de alimentación | 3.3 V or 5 V (single supply) |
| Regulated Output | 3.3 V (when powered from 5 V) |
| VIO (28-pin) | Internally tied to 3.3 V |
| Corriente de alimentación | 13 mA (typical, per distributor listing) |
| Temperatura de funcionamiento | [-40 °C, +85 °C] |
| Encapsulado | 28-QFN (5x5 mm) |
| Tipo de montaje | Surface Mount |
| Packaging | Tray |
| Estado RoHS | Compliant |
| USB Features | Suspend, resume, remote wakeup |
Configuración de pines de XR21B1421IL28-F
| Pin 1 | GND — Ground (also exposed thermal pad) |
| Pin 2 | VBUS — USB VBUS sense input (5 V) |
| Pin 3 | DP — USB D+ data line |
| Pin 4 | DM — USB D- data line |
| Pin 5 | VDD33 — Regulated 3.3 V output (internal LDO) |
| Pin 6 | VCC — 5 V or 3.3 V supply input |
| Pin 7 | RESET — Reset input (active-low per datasheet) |
| Pin 8 | GPIO0 — General-purpose I/O / wake event |
| Pin 9 | GPIO1 — General-purpose I/O / wake event |
| Pin 10 | GPIO2 — General-purpose I/O |
| Pin 11 | GPIO3 — General-purpose I/O |
| Pin 12 | TXD — UART transmit output (to host MCU RX) |
| Pin 13 | RXD — UART receive input (from host MCU TX) |
| Pin 14 | RTS — UART request-to-send output (hardware flow control) |
| Pin 15 | CTS — UART clear-to-send input (hardware flow control) |
| Pin 16 | RI — Ring indicator input |
| Pin 17 | DSR — Data-set-ready input |
| Pin 18 | DCD — Data-carrier-detect input |
| Pin 19 | DTR — Data-terminal-ready output |
| Pin 20 | NC — Not connected (per datasheet) |
| Pin 21 | NC — Not connected (per datasheet) |
| Pin 22 | NC — Not connected (per datasheet) |
| Pin 23 | TEST — Test mode pin (tie to GND in normal operation) |
| Pin 24 | XIN — Crystal / clock input (12 MHz per datasheet) |
| Pin 25 | XOUT — Crystal output |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | NC — Not connected (per datasheet) |
| Pin 28 | EPAD — Exposed thermal pad - must be soldered to GND plane |
Aplicaciones típicas
XR21B1421IL28-F es adecuado para 6 aplicacións: USB-to-Serial Adapter Dongles, Point-of-Sale and Kiosk UART Peripherals, Industrial Sensor and Meter Data Loggers, Medical Instrument Data Ports, Embedded MCU Debug and Console Ports, IoT Gateway and Edge Node USB Upgrades.
USB-to-Serial Adapter Dongles
The XR21B1421IL28-F is well suited to USB-to-serial adapter dongles that connect legacy UART peripherals to modern PCs and embedded hosts. Its 12 Mbps USB 2.0 Full-Speed interface and HID-class enumeration remove the need for a custom host driver, so the dongle enumerates on Windows, Linux, and macOS without an INF file. The 28-QFN (5x5) package keeps the dongle BOM small by integrating the 3.3 V regulator and removing the need for an external crystal on many reference designs. Configurable Vendor ID / Product ID strings let the OEM brand the dongle to its own product line.
Recomendado
Point-of-Sale and Kiosk UART Peripherals
In point-of-sale (POS) terminals and self-service kiosks, the XR21B1421IL28-F adds USB connectivity to barcode scanners, receipt printers, and magnetic-stripe readers that natively speak UART. HID-class enumeration is critical here because locked-down POS hosts frequently disallow custom driver installation, and the XR21B1421's driverless behavior sidesteps that restriction entirely. The 13 mA typical supply current stays comfortably below USB suspend limits, and the integrated 3.3 V regulator simplifies bus-powered designs where the host 5 V VBUS is the only supply rail available.
Recomendado
Industrial Sensor and Meter Data Loggers
Industrial sensor and meter data loggers use the XR21B1421IL28-F to expose UART sensor data over USB to laptops running configuration software. The -40 °C to +85 °C industrial temperature range covers outdoor enclosures, factory floors, and unheated cabinets, while the integrated 3.3 V regulator eliminates an external LDO and reduces the BOM count by one part. Hardware flow control (RTS/CTS) on the UART side prevents frame loss at high baud rates when bursts of telemetry exceed the USB endpoint budget.
Recomendado
Medical Instrument Data Ports
Medical instruments such as portable patient monitors and handheld diagnostic tools integrate the XR21B1421IL28-F to expose a service / data port over USB without burdening the main MCU with a USB stack. HID-class driverless enumeration lets field-service laptops connect to the device on any standard OS without installing vendor software, accelerating service workflows. The 5 V single-supply operation with on-chip 3.3 V regulation simplifies medical-cart power architectures that already provide a regulated 5 V rail. Configurable remote-wakeup lets the host wake the instrument from low-power standby.
Recomendado
Embedded MCU Debug and Console Ports
Embedded development boards use the XR21B1421IL28-F as a USB-to-UART console bridge so engineers can connect a development PC to the target MCU's serial console over a standard USB cable. The 12 Mbps USB Full-Speed link is more than adequate for typical 115200 to 921600 baud debug streams, and the hardware flow control pins give clean handling of bootloader handshakes. The compact 28-QFN (5x5) footprint is small enough for low-cost dev boards where every square millimeter of PCB real estate matters.
Recomendado
IoT Gateway and Edge Node USB Upgrades
IoT gateways and edge nodes that need to add a USB device port to an MCU lacking USB hardware use the XR21B1421IL28-F to expose a UART over USB for provisioning, firmware update, and field diagnostics. HID-class driverless behavior is valuable on OT-managed enterprise hosts where custom drivers cannot be installed, and configurable Vendor ID / Product ID strings allow per-customer branding. The integrated 3.3 V LDO removes a power-rail IC, reducing BOM cost in price-sensitive edge-node designs.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para XR21B1421IL28-F — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | XR21B1421IL28 | XR21B1421IL28TR-F | XR21B1421IL24-F |
|---|---|---|---|---|
| Brand | MaxLinear | MaxLinear | MaxLinear | MaxLinear (24-QFN, NOT pin-compatible) |
| Package | 28-QFN (5x5) | 28-QFN (5x5) - same | 28-QFN (5x5) - same | 24-QFN - DIFFERENT footprint |
| USB Data Rate | 12 Mbps (USB 2.0 FS) | 12 Mbps (USB 2.0 FS) | 12 Mbps (USB 2.0 FS) | 12 Mbps (USB 2.0 FS) |
| USB Class | HID (driverless) | HID (driverless) | HID (driverless) | HID (driverless) |
| Supply Voltage | 3.3 V or 5 V | 3.3 V or 5 V | 3.3 V or 5 V | 3.3 V or 5 V |
| Internal 3.3 V LDO | Yes | Yes | Yes | Yes |
| VIO Pin | Internally tied to 3.3 V | Internally tied to 3.3 V | Internally tied to 3.3 V | Separate external VIO pin |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C |
| UART Flow Control | RTS/CTS, XON/XOFF | RTS/CTS, XON/XOFF | RTS/CTS, XON/XOFF | RTS/CTS, XON/XOFF |
Diferenciadores clave
- Driverless HID-class enumeration on all major host OSes (frente a FTDI FT232R (vendor-specific VCP driver))
- Integrated 3.3 V LDO eliminates external regulator (frente a FT232R (requires external 3.3 V regulator in 5 V designs))
- Compact 28-QFN (5x5 mm) footprint (frente a FT232R SSOP-28 (larger PCB area))
Notas de diseño
Route the USB D+ (pin 3) and D- (pin 4) traces as a 90 Ω differential pair with matched length to within 150 mil. Place the decoupling capacitor on VCC (pin 6) within 100 mil of the pin, and tie the exposed thermal pad (pin 28) to a continuous ground pour with at least 8 thermal vias for heat dissipation. Avoid routing digital signal traces under the crystal traces (pins 24-25) to prevent coupling into the 12 MHz reference.
When powered from 5 V VBUS, the integrated 3.3 V LDO on pin 5 (VDD33) can supply up to ~30 mA to external logic, but USB suspend current must stay under 2.5 mA for a unit load. Place a 4.7 µF ceramic bypass on VDD33 close to the pin to keep the LDO stable under load steps, and verify USB compliance suspend current with the configured VID/PID strings.
Do not connect the 28-QFN EPAD (pin 28) to anything other than GND; floating the pad prevents the internal regulator and thermal paths from working correctly. Verify the TEST pin (pin 23) is tied to GND in normal operation - leaving it floating can put the part into test mode and break USB enumeration. Ensure the Vendor ID is not 0x0000/0xFFFF, which the USB specification reserves and which will fail enumeration on most hosts.
Información de cumplimiento
RoHS and lead-free status inferred from the -F suffix and MaxLinear product page. Halogen-free and conflict-minerals declarations are not present in the verified web data and are marked unknown.
