XR21V1410
1-CH FULL-SPEED USB UART
SEPTEMBER 2010
REV. 1.1.0
GENERAL DESCRIPTION
The XR21V1410 (V1410) is an enhanced 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 V1410 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 V1410 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. If required, the multidrop (9-bit) mode
with automatic half-duplex transceiver control feature
further
simplifies
typical
multidrop
RS-485
applications.
The V1410 operates from a single 2.97 to 3.63 volt
power supply and has 5V tolerant inputs. The V1410
is available in a 16-pin QFN package.
WHQL certified software drivers for Windows 2000,
XP, Vista, 7 and CE, as well as Linux and Mac are
supported for the XR21V1410.
APPLICATIONS
FEATURES
•
USB 2.0 Compliant, Full-Speed (12 Mbps)
s
Supports USB suspend, resume and remote
wakeup operations
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
Odd, even, mark, space, or no parity
Automatic Hardware (RTS/CTS or DTR/DSR)
Flow Control
Automatic Software (Xon/Xoff) Flow Control
Multidrop mode
Auto Transceiver Enable
Half-Duplex mode
Selectable GPIO or Modem I/O
•
Enhanced UART Features
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s
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•
Portable Appliances
•
External Converters (dongles)
•
Battery-Operated Devices
•
Cellular Data Devices
•
Factory Automation and Process Controls
•
Industrial applications
•
Internal 48 MHz clock
•
Single 2.97-3.63V power supply
•
5V tolerant inputs
•
16-pin QFN package
•
Virtual COM Port WHQL certified drivers
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Windows 2000, XP, Vista and Win7
Windows CE 4.2, 5.0, 6.0
Linux
Mac
Exar
Corporation 48720 Kato Road, Fremont CA, 94538
•
(510) 668-7000
•
FAX (510) 668-7017
•
www.exar.com
XR21V1410
1-CH FULL-SPEED USB UART
F
IGURE
1. XR21V1410 B
LOCK
D
IAGRAM
REV. 1.1.0
Internal
48MHz
Oscillator
USBD+
USBD-
USB Slave
Interface
Fractional
BRG
128-byte
TX FIFO
384-byte
RX FIFO
TX
RX
GPIO5/RTS#
GPIO4/CTS#
GPIO3/DTR#
GPIO2/DSR#
GPIO1/CD#
GPIO0/RI#
SDA
SCL
3.3V VCC
GND
IC
Interface
2
Internal
Status and
Control
Registers
GPIOs/
Modem IO
UART
F
IGURE
2. P
IN
O
UT
A
SSIGNMENT
SDA
SCL
RX
3
GPIO5/RTS#
12 11 10
GND 13
16-Pin
USBD- 14
QFN
USBD+ 15
VCC 16
1
GND
2
LOWPOWER
TX
9
8 GPIO0/RI#
7 GPIO1/CD#
6 GPIO2/DSR#
5 GPIO3/DTR#
4
GPIO4/CTS#
ORDERING INFORMATION
P
ART
N
UMBER
XR21V1410IL16
P
ACKAGE
16-pin QFN
O
PERATING
T
EMPERATURE
R
ANGE
-40° to +85°
C
C
D
EVICE
S
TATUS
Active
2
XR21V1410
REV. 1.1.0
1-CH FULL-SPEED USB UART
PIN DESCRIPTIONS
Pin Description
N
AME
UART Signals
RX
10
I
UART Channel A Receive Data or IR Receive Data. This pin has an
internal pull-up resistor. Internal pull-up resistor is not disabled during
suspend mode.
UART Channel A Transmit Data or IR Transmit Data.
General purpose I/O or UART Ring-Indicator input (active low) or
Remote Wakeup input. See
“Section 1.5.11, Remote Wakeup” on
page 10
.
This pin has an internal pull-up resistor which is disabled during suspend
mode. If using this GPIO as an input, an external pull-up resistor is
required to minimize the device power consumption in the suspend
mode.
General purpose I/O or UART Carrier-Detect input (active low). This pin
has an internal pull-up resistor which is disabled during suspend mode.
If using this GPIO as an input, an external pull-up resistor is required to
minimize the device power consumption in the suspend mode.
General purpose I/O or UART Data-Set-Ready input (active low).
See
16-QFN
P
IN
#
T
YPE
D
ESCRIPTION
TX
GPIO0/RI#
9
8
O
I/O
GPIO1/CD#
7
I/O
GPIO2/DSR#
6
I/O
”Section 1.5.5, Automatic DTR/DSR Hardware Flow Control”
on page 9.
This pin has an internal pull-up resistor which is disabled during suspend
mode. If using this GPIO as an input, an external pull-up resistor is
required to minimize the device power consumption in the suspend
mode.
GPIO3/DTR#
5
I/O
General purpose I/O or UART Data-Terminal-Ready output (active low).
See ”Section 1.5.5, Automatic DTR/DSR Hardware Flow Con-
trol” on page 9.
This pin has an internal pull-up resistor which is disabled during suspend
mode. If using this GPIO as an input, an external pull-up resistor is
required to minimize the device power consumption in the suspend
mode.
GPIO4/CTS#
4
I/O
General purpose I/O or UART Clear-to-Send input (active low).
See
”Section 1.5.4, Automatic RTS/CTS Hardware Flow Control”
on page 8.
This pin has an internal pull-up resistor which is disabled during suspend
mode. If using this GPIO as an input, an external pull-up resistor is
required to minimize the device power consumption in the suspend
mode.
GPIO5/RTS#
3
I/O
General purpose I/O or UART Request-to-Send output (active low).
See ”Section 1.5.4, Automatic RTS/CTS Hardware Flow Con-
trol” on page 8.
This pin has an internal pull-up resistor which is disabled during suspend
mode. If using this GPIO as an input, an external pull-up resistor is
required to minimize the device power consumption in the suspend
mode.
3
XR21V1410
1-CH FULL-SPEED USB UART
Pin Description
N
AME
USB Interface Signals
USBD+
USBD-
I
2
C Interface Signals
SDA
11
OD
I
2
C-controller data input/output (open-drain). An optional external I
2
C
EEPROM can be used to store default configurations upon power-up
including the USB Vendor ID and Device ID. See
Table 3
. A pull-up
resistor (typically 4.7 to 10 KOhms) is required.
If an EEPROM is not used, this pin can be used with the SCL pin to
select the Remote Wake-up and Power modes. An external pull-up or
pull-down resistor is required. See
Table 2
I
2
C-controller serial input clock. An optional external I
2
C EEPROM can
be used to store default configurations upon power-up including the USB
Vendor ID and Device ID. See
Table 3
. A pull-up resistor (typically 4.7
to 10 KOhms) is required.
If an EEPROM is not used, this pin can be used with the SDA pin to
select the Remote Wake-up and Power modes. An external pull-up or
pull-down resistor is required. See
Table 2
15
14
I/O
I/O
USB port differential data plus. This pin has a 1.5 K Ohm internal pull-up
resistor.
USB port differential data minus.
16-QFN
P
IN
#
T
YPE
D
ESCRIPTION
REV. 1.1.0
SCL
12
I
Miscellaneous Signals
LOWPOWER
2
O
Low power status output. This pin will be asserted whenever the V1410
device is placed into the suspend state.
This pin is sampled momentarily at power-up or at any USB bus reset to
configure the polarity of the LOWPOWER output during suspend mode.
An external (10K) pull-up resistor will cause the LOWPOWER pin to be
asserted HIGH during suspend mode. An external (3.3K) pull-down resis-
tor will cause the LOWPOWER pin to be asserted LOW during suspend
mode.
+3.3V power supply. (Note that all device inputs are 5V tolerant.)
Power supply common, ground.
VCC
GND
16
1, 13
Pwr
Pwr
N
OTE
:
Pin type: I=Input, O=Output, I/O= Input/output, OD=Output Open Drain.
4
XR21V1410
REV. 1.1.0
1-CH FULL-SPEED USB UART
1.0 FUNCTIONAL DESCRIPTIONS
1.1
USB interface
The USB interface of the V1410 is compliant with the USB 2.0 Full-Speed Specifications. The USB
configuration model presented by the V1410 to the device driver is compatible to the Abstract Control Model of
the USB Communication Device Class (CDC-ACM). The V1410 uses the following set of parameters:
•
1 Control Endpoint
s
Endpoint 0 as outlined in the USB specifications
•
1 Configuration is supported
•
2 interfaces for the UART channel
s
s
Single interrupt endpoint
Bulk-in and bulk-out endpoints
USB Vendor ID
1.1.1
Exar’s USB Vendor ID is 0x04E2. This is the default Vendor ID that is used for the V1410 unless a valid
EEPROM is present on the I
2
C interface signals. If a valid EEPROM is present, the Vendor ID from the
EEPROM will be used.
1.1.2
USB Product ID
The default USB Product ID for the V1410 is 0x1410. If a valid EEPROM is present, the Product ID from the
EEPROM will be used.
1.2
USB Device Driver
The V1410 device can be used with either a standard CDC-ACM driver or a custom driver. When the CDC-
ACM driver is used, the driver has no knowledge of the V1410 device registers. Because of this, the V1410
device is initialized to the following settings:
T
ABLE
1: V1410 R
EGISTER
D
EFAULTS WITH
CDC-ACM D
RIVER
R
EGISTER
FLOW_CONTROL
GPIO_MODE
GPIO_DIRECTION
GPIO_INT_MASK
V
ALUE
0x01
0x01
0x08
0x30
N
OTES
Hardware flow control
RTS / CTS flow control
DTR configured as an output (in addition to RTS which is set by
GPIO_MODE)
CD and DSR are interrupt sensitive, i.e. can cause a USB inter-
rupt to be generated
5
