XR21B1424_17 Datasheet, PDF (1/64 Pages) Exar Corporation – Enhanced 4-Ch Full-Speed USB UART

XR21B1424
Enhanced 4-Ch Full-Speed USB UART
General Description
The XR21B1424 is an enhanced Universal Asynchronous Receiver and
Transmitter (UART) bridge to USB interface. The USB interface is fully
compliant to the USB 2.0 (Full-Speed) specification with 12 Mbps USB
data transfer rate. The USB interface also supports USB suspend,
resume and remote wakeup operations. The USB Vendor ID, Product ID,
power mode, remote wakeup support, maximum power, and numerous
other settings may be programmed in the on-chip OTP memory via the
USB interface.
The XR21B1424 includes an internal oscillator and does not require an
external crystal/oscillator. Any UART baud rate from 300 bps to 12 Mbps
may be generated with this internal clock and the fractional baud rate gen-
erator.
The UART pins for each port may also be configured as GPIO; direction,
state, output driver type and input pull-up or pull-down resistors are pro-
grammed either through on chip OTP, or on the fly via memory mapped
registers.
Large 512-byte TX and RX FIFOs prevent buffer overflow errors and opti-
mize data throughput. Automatic half-duplex direction control and optional
multi drop (9-bit) mode simplify both hardware and software in half-duplex
RS-485 applications. Wide mode allows for each individual received char-
acter to be monitored for errors.
The XR21B1424 uses the native OS CDC-ACM driver or a MaxLinear
supplied custom driver. MaxLinear provides WHQL/HCK-certified soft-
ware drivers for Windows 2000, XP, Vista, 7, 8, 8.1 and 10 as well as soft-
ware drivers for Windows CE, Linux and Mac OS X. Full source code is
available.
The XR21B1424 operates from a single 5V or 3.3V power supply. When
powered with 5V input, a regulated 3.3V output is supplied.
Typical Application
FEATURES
• ±15kV ESD on USBD+/USBD-
• USB 2.0 Compliant, Full-Speed (12Mbps)
• Unique pre-programmed USB serial number
• Internally generated 48MHz core clock
• Enhanced UART features
• Baud rates from 300 bps to 12 Mbps
• Fractional Baud Rate Generator
• 512-byte TX and 512-byte RX FIFOs
• Auto Hardware / Software Flow Control
• Multidrop and Half-Duplex Modes
• Auto RS-485 Half-Duplex Control
• Selectable GPIO or Modem I/O
• Up to 10 GPIOs per channel
• 5V tolerant GPIO inputs
• Suspend state GPIO configuration
• Configurable clock output
• 64-pin LQFP package
• Industrial -40°C to +85°C Temperature
Range
APPLICATIONS
• Building Automation
• Security Systems
• Factory and Process Control
• ATM Terminals
• USB to Serial Controllers
Ordering Information – page 64
XR21B1424
MCU
USB
UART
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1 / 64




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exar.com/XR21B1424
Rev 1C