XR21V1414

4-Ch Full-Speed USB UART

Overview

Information 4-Ch Full-Speed USB UART
Data Bus Interface USB 2.0
Max Data Rate 5V (Mbps) na
Max Data Rate 3.3V (Mbps) 12
Tx FIFO (Bytes) 128
Rx FIFO (Bytes) 384
Auto Flow Control
Multidrop (9-bit) Mode
Fractional Baud Rate Generator
Power Down Mode
Supply Voltage Range VCC (V) 2.97 to 3.63
IrDA Sup
5V Tolerant Inputs
Max UART/GPIO Input Voltage (V) 5.5
Max UART/GPIO Output Voltage (V) VCC
Package TQFP-48
Temperature Range (°C) -40 to 85
Auto RS-485
Auto Half-Duplex Control
# of Channels 4
Show more

The XR21V1414 is an enhanced 4-channel Universal Asynchronous Receiver and Transmitter (UART) with a USB interface. The USB interface is fully compliant to Full Speed USB 2.0 specification that supports 12 Mbps USB data transfer rate. The USB interface also supports USB suspend, resume and remote wakeup operations.

The XR21V1414 operates from an internal 48MHz clock therefore no external crystal/oscillator is required like previous generation UARTs. With the fractional baud rate generator, any baud rate can accurately be generated using the internal 48MHz clock.

The large 128-byte Tx FIFO and 384-byte RX FIFO of the XR21V1414 helps to optimize the overall data throughput for various applications. The Automatic Transceiver Direction control feature simplifies both the hardware and software for half-duplex RS-485 applications. The multidrop (9-bit) mode with automatic half-duplex transceiver control feature further simplifies typical multidrop RS-485 applications.

The XR21V1414  operates from a single 2.97 to 3.63 volt power supply and has 5V tolerant inputs.

Software drivers for Windows 2000, XP, Vista, 7, 8, and CE, as well as Linux and Mac are supported for the XR21V1414.
 

  • USB 2.0 Compliant Interface
    • Supports 12 Mbps USB full-speed data rate
    • Supports USB suspend, resume and remote wakeup operations
  • Enhanced UART Features
    • Data rates up to 12 Mbps
    • Fractional Baud Rate Generator
    • 128 byte TX FIFO
    • 384 byte RX FIFO
    • 7, 8 or 9 data bits, 1 or 2 stop bits
    • Automatic Hardware (RTS/CTS or DTR/DSR)Flow Control
    • Automatic Software (Xon/Xoff) Flow Control
    • Multidrop mode w/ Auto Half-Duplex Transceiver Control
    • Multidrop mode w/ Auto TX Enable
    • Half-Duplex mode
    • Selectable GPIO or Modem I/O
  • Internal 48 MHz clock
  • Single 2.97-3.63V power supply
  • 5V tolerant inputs 
  • Virtual COM Port Drivers
    • Windows 2000, XP, Vista, 7, and 8
    • Windows CE 4.2, 5.0, 6.0, and 7.0
    • Linux
    • Mac
  • Download Software Drivers

  • Portable Appliances
  • External Converters (Dongles)
  • Battery-Operated Devices
  • Cellular Data Devices
  • Factory Automation and Process Controls
  • Industrial Applications

Documentation & Design Tools

Type Title Version Date File Size
Data Sheets XR21V1414 4-CH FULL-SPEED USB UART 1.3.0 December 2013 408.8 KB
Application Notes AN202, USB UART Board Design Considerations for USB Compliance June 2021 647.5 KB
Application Notes AN-226, Windows Driver Customization for USB UARTs R00 February 2020 2.5 MB
Application Notes AN205, Comparison of the XR21V1410 and the XR21B1411 1.0.0 March 2011 215.8 KB
Application Notes AN213, USB Basics for the MaxLinear Family of USB UARTS 1.0.0 March 2011 107.3 KB
Application Notes DAN-190, MaxLinear UARTs in RS-485 Applications 1.0.0 April 2008 147.3 KB
User Guides & Manuals XR21B14xx_XR21V14xx USB UART Design Guide 01 May 2020 2.3 MB
Software: GUIs & Utilities Sample USB UART GUI (Serial Test App) 1.2.0.0 July 2021 1.4 MB
Software: GUIs & Utilities Android Application 1C November 2015 476.6 KB
Software: GUIs & Utilities XR21V141x Linux EEPROM Programming Utility 2.0.0 April 2013 2.2 KB
Software: GUIs & Utilities XR21V141x Windows EEPROM Programming Utility 1.0.0.7A December 2012 963.9 KB
Product Flyers Full-Speed USB UART Family 1.0 February 2016 842.4 KB
Product Flyers Full-Speed USB UART Family 1.0.0 July 2009 329.2 KB
Software: Drivers Linux 3.6.x and Newer 1D September 2021 29.9 KB
Software: Drivers Windows XP, Vista, 7, 8, 8.1, 10 2.6.0.0 December 2019 145.7 KB
Software: Drivers Linux 2.6.18 to 3.4.x 1A January 2015 19.1 KB
Software: Drivers Mac 1.0.4 October 2013 171.3 KB
Schematics & Design Files XR21V1414-0A-EB Evaluation Board Schematics & Design Files 1.0.0 May 2011 1.7 MB
Schematics & Design Files XR21V1414-0B-EB Evaluation Board Schematics & Design Files 1.0.0 May 2011 1 MB
Product Brochures Interface Brochure October 2019 1.3 MB
Simulation Models
Package Type Vcc Temp Mode Version File
TQFP 3.3V Industrial USB 1
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Quality & RoHS

Part Number RoHS | Exempt RoHS Halogen Free REACH TSCA MSL Rating / Peak Reflow Package
XR21V1414IM48-F N Y Y Y Y TQFP48 Y
XR21V1414IM48TR-F N Y Y Y Y TQFP48 Y

Click on the links above to download the Certificate of Non-Use of Hazardous Substances.

Additional Quality Documentation may be available, please Contact Support.

Parts & Purchasing

Part Number Pkg Code Min Temp Max Temp Status Suggested Replacement Buy Now Order Samples PDN
XR21V1414IM48-C1-F TQFP48 OBS XR21V1414IM48-F
XR21V1414IM48-C2-F TQFP48 OBS XR21V1414IM48-F
XR21V1414IM48-C3-F TQFP48 OBS XR21V1414IM48-F
XR21V1414IM48-F TQFP48 -40 85 Active Order
XR21V1414IM48TR-F TQFP48 -40 85 Active Order
XR21V1414IM-0A-EB Board Active
XR21V1414IM-0B-EB Board Active
Show obsolete parts
Part Status Legend
Active - the part is released for sale, standard product.
EOL (End of Life) - the part is no longer being manufactured, there may or may not be inventory still in stock.
CF (Contact Factory) - the part is still active but customers should check with the factory for availability. Longer lead-times may apply.
PRE (Pre-introduction) - the part has not been introduced or the part number is an early version available for sample only.
OBS (Obsolete) - the part is no longer being manufactured and may not be ordered.
NRND (Not Recommended for New Designs) - the part is not recommended for new designs.

Packaging

Pkg Code Details Quantities Dimensions PDF
TQFP48
  • JEDEC Reference: MO-026
  • MSL Pb-Free: L3 @ 260ºC
  • MSL SnPb Eutectic: n/a
  • ThetaJA: 59.0ºC/W
  • Bulk Pack Style: Tray
  • Quantity per Bulk Pack: 250
  • Quantity per Reel: 1500
  • Quantity per Tube: n/a
  • Quantity per Tray: 250
  • Reel Size (Dia. x Width x Pitch): 330 x 16 x 12
  • Tape & Reel Unit Orientation: Quadrant 2
  • Dimensions: mm
  • Length: 7.0
  • Width: 7.0
  • Thickness: 1.2
  • Lead Pitch: 0.5

Notifications

Distribution Date Description File
01/31/2017 Addition of qualified 12 inch wafer processing line in Global Foundries, in addition to the currently qualified 8 inch wafer processing. Note: Reliability report will be available February 17, 2017.
08/17/2016 Qualification of ANST as an alternate manufacturing site.
09/02/2015 Metal mask change for yield improvement Process change
12/05/2013 Addition of an alternate qualified assembly site, ASE Chung-Li (Taiwan) for assembly using copper or gold wire bonding. Material change and alternate assembly site.
10/03/2013 Product Discontinuation Notification Discontinued.
03/30/2012 XR21V141x Product Change from Rev B to Rev D Product improvement.
08/10/2011 Material change and a new assembly & test supplier (ASE, Kunshan). Business consolidation.

FAQs & Support

Search our list of FAQs for answers to common technical questions.
For material content, environmental, quality and reliability questions review the Quality tab or visit our Quality page.
For ordering information and general customer service visit our Contact Us page.

Submit a Technical Support Question As a New Question

For some UARTs, Microsoft certified drivers are available for Windows Operating System and can be downloaded via Windows Update. These drivers and others, including for Linux and other Operating Systems can be found by visiting https://www.exar.com/design-tools/software-drivers Please note Software Driver Use Terms.

 

 
You can also get to this link by going to the exar.com website, clicking on Support (in black bar near top of page), then click on Design Tools, then under Evaluation Hardware and Software (towards right of page) click on Software Drivers.
 
 

Click on the version link under Driver Version of the desired type of UART, part number and operating system. A zip file is downloaded which contains a ReadMe file with instructions.

Links to datasheets and product family pages are in the software driver table for easy reference. 

No, Auto RTS and Auto CTS are independent. Auto RTS is toggled by the UART receiver. Auto CTS is monitored by the UART Transmitter.

No, Auto RTS and Auto CTS will work normally without the interrupts enabled.

No, software flow control characters are not loaded into the RX FIFO.

Auto RS485 Half-Duplex Control feature overrides the Auto RTS flow control feature if both features use the RTS# output pin. Both features can only be used simultaneously if the Auto RS485 control output is not the RTS# output. For some UARTs, the Auto RS485 control output is not the RTS# output.

The polarity of the RS485 control output varies from one UART to another. For some UARTs, an inverter may be required. Some of the newer UARTs have register bits that can change that polarity of the RS485 control output.

All of the UARTs that have the IR mode supports up to 115.2Kbps as specified in IrDA 1.0. The newer I2C/SPI UARTs can support up to 1.152Mbps as specified in IrDA 1.1.

Find the product page of the part that you want to get an evaluation board for and click on Parts & Purchasing. Example:

 

Find the icons under Buy Now or Order Samples:

 
 

Click on the Buy Now icon and see who has stock and click on the Buy button:

 
 
 

Alternatively, you can click on the Order Samples

 
 

If the icons are missing, then contact Customer Support.

The -F suffix indicates ROHS / Green compliance:
https://www.exar.com/quality-assurance-and-reliability/lead-free-program

Visit the product page for the part you are interested in.  The part's status is listed in the Parts & Purchasing section.  You can also view Product Lifecycle and Obsolescence Information including PDNs (Product Discontinuation Notifications).
 
To visit a product page, type the part into the search window on the top of the MaxLinear website.
 
In this example, we searched for XRA1201.  Visit the product page by clicking the part number or visit the orderable parts list by clicking "Orderable Parts". 
 
 
 

 

  

The Parts & Purchasing section of the product page shows the Status of all orderable part numbers for that product.  Click Show obsolete parts, to see all EOL or OBS products.

 
 
 

 

Connect the USB data pins directly to the host or upstream hub. Connections should be impedance controlled to 90 ohms differential with short traces and no stubs. Connecting any other components that are not high impedance (series or shunt resistance, capacitance or inductance) will corrupt the USB data signaling and can prevent communication between the host and device. ESD protection diodes may be used and some EMI filters may also have only a slight impact on impedance but should be demonstrated for compliance with USB 2.0 devices. See Application Notes AN202 (USB UART Board Design Recommendations and Considerations for USB Compliance), section 2.0 Design Considerations  for more. 

1. Native drivers: Native drivers may be found in all major OS such as Windows, Linux, and Max OSX. Typically these drivers will be automatically loaded. In some cases, these are basic drivers and may have limitations on advanced device functionality, however. USB HID, Hub and CDC-ACM drivers are examples of native drivers. The CDC-ACM driver be used with our CDC-ACM class USB UARTs, but has limited functionality.

 

2. MaxLinear custom drivers: MaxLinear custom drivers may be used to support additional functionality in MaxLinear devices. For example, the MaxLinear custom driver for USB UARTs overcomes the limitations of the native CDC-ACM driver. See https://www.exar.com/design-tools/software-drivers for a list of and access to the drivers that we currently have. In some cases, the MaxLinear driver can also be customized, or source code can be provided after executing a Software License Agreement.

Yes: Go to the product page (XR22804 example below), click on the documentation tab on left, click on “Sample USB UART GUI” under Software:

 

It depends on the baud rate. For example, for a start bit, 8 data bits, no stop bit and 1 stop bit, the maximum baud rate deviation is 4.76%. For more information, see https://www.exar.com/appnote/dan108.pdf

Most UARTs use RTS#, however in addition to using the RTS# output as the Auto RS485 control output, the XR21B1420/1421/1422/1424 can use the DTR# output as the Auto RS485 control output.

The following lines of code must be modified in the xr_usb_serial_hal.c file in the xr_usb_serial_set_flow_mode function at the end of the function:

 

Change from:

xr_usb_serial_set_reg(xr_usb_serial, xr_usb_serial->reg_map.uart_flow_addr, flow);

xr_usb_serial_set_reg(xr_usb_serial, xr_usb_serial->reg_map.uart_gpio_mode_addr, gpio_mode);

 
For active low TX, change to:

xr_usb_serial_set_reg(xr_usb_serial, xr_usb_serial->reg_map.uart_flow_addr, 0x0);

xr_usb_serial_set_reg(xr_usb_serial, xr_usb_serial->reg_map.uart_gpio_mode_addr, 0x3);

 

For active high TX, change to:

xr_usb_serial_set_reg(xr_usb_serial, xr_usb_serial->reg_map.uart_flow_addr, 0x0);

xr_usb_serial_set_reg(xr_usb_serial, xr_usb_serial->reg_map.uart_gpio_mode_addr, 0xB);

All of MaxLinear / Exar's USB UARTs are CDC class / CDC-ACM compliant, except for XR21B1421 which is an HID class device. This means they can use a native CDC driver. All major OS have native CDC drivers, except Windows prior to Windows 10.

None of the MaxLinear / Exar USB UARTs require their custom driver, however they will have certain limitations when not using it. The native CDC driver is not capable of accessing the internal memory map of any device. As a result, when using the native CDC driver, the device “defaults” to a particular configuration. The main implications of this default configuration are that hardware RTS/CTS flow control is enabled and that other settings / advance settings are not configurable. Some devices, for example the XR21B1411 which has an internal OTP memory, can be programmed to change this default configuration, but the configuration cannot be changed “on the fly”.

1.  Enter root privileges: sudo -i
2.  Enter admin password.
3.  Edit /etc/modules file.  Append xr_usb_serial_common to the end of the file.
4.  Build the Exar/MxL driver from the folder using "make", confirm that the xr_usb_serial_common.ko file is successfully created.
5.  Run command: uname -r
This will return the kernal version currently in use. 
6.  Copy the resulting xr_usb_serial_common.ko to /lib/modules/2.6.38.8-generic in the above path with the kernal version that was returned in step 5.
7.  Run depmod.
8.  Reboot. 
9.  Connect the Exar/MxL USB UART.  Using ls/dev/tty* confirm /dev/ttyUSBn ports (Exar driver loaded) for Exar/MxL USB UART.
10. Connect another CDC device (not Exar/MxL), and confirm both /dev/ttyUSBn and /dev/ACMn ports. 

The maximum allowed bus-powered suspend current is 2.5mA per device function. The device function may not be the same as the IC, as there may be multiple device functions per IC. See the individual datasheet for a list of device functions. For example, the XR22804 has 8 device functions: an embedded hub, the Ethernet MAC and Phy, 4 UARTs, I2C controller and EDGE controller. Therefore, the XR22804 maximum allowed bus-powered suspend current is 8 x 2.5mA or 20mA. However, power used by all supporting XR22804 external components that use power from the USB host VBUS power must be included in the suspend current.

It is recommended, especially when connecting a USB cable to the VBUS 5V source.  See Application Note AN202 (USB UART Board Design Recommendations and Considerations for USB Compliance), section 2.2.2 In-rush Current for more.

The external EEPROM can be used to modify various USB configuration descriptors such as the Vendor ID, Product ID, Device Attributes and maximum power consumption. See Application Note AN202 (USB UART Board Design Recommendations and Considerations for USB Compliance), section 2.3 External EEPROM or on-chip OTP for more.

Once enumeration is completed, the host and device may carry out data transfers. Four type of data transfers are defined: control, bulk data transfers, interrupts and Isochronous data transfers. Although USB UARTs do support the control, bulk data transfers and interrupts, they do not support Isochronous data transfers which would be needed for applications streaming audio or video. See Application Note AN213 (section 3.3.2) for a description of each.