Exar – XR21B142x Family: USB to Serial Bridge

XR21B142x Family Provides Superior Performance and Ease of Design

Highly-Integrated Device Eliminates Need for External Components

  • Industry leading +/- 15kV ESD on USBD+/USBD-
  • Internal 48MHz oscillator
  • Integrated 5V to 3.3V LDO with regulated 3.3V output

USB 2.0 (Full-Speed) Compliant Interface

  • USB suspend, resume, remote wake-up
  • Bus-powered or self-powered configuration
  • Unique pre-programmed USB serial number
  • HID class USB interface (XR21B1421)

Enhanced UART Features

  • Any baud rate up to 12Mbps
  • 512-byte TX and 512-byte RX FIFOs
  • Auto hardware/software flow control
  • Auto RS-485 half-duplex direction control
  • Multidrop and half-duplex modes
  • Full modem interface or GPIOs
  • 5V tolerant inputs

Up to 10 Fully Configurable GPIOs

  • Push-pull or open-drain output
  • Inputs with internal pull-up/pull-down resistors
  • TX or RX LED toggling
  • Configurable clock output
  • Suspend state GPIO configuration

Space Saving Package Options

  • QFN-24, QFN-28, QFN-40 and LQFP-64 packages


  • Smart grid data collection
  • Data aggregators and concentrators
  • Security and access control systems
  • ATM and gaming terminals
  • Rugged USB to serial converters


  • Portable consumer products
  • Keyboard, video, mouse
  • Medical Diagnostics
    • Biometric data collection
    • Portable blood glucose meters