XR19L200 Datasheet, PDF (5/40 Pages) Exar Corporation – SINGLE CHANNEL INTEGRATED UART AND RS-232 TRANSCEIVER

PRELIMINARY
XR19L200
REV. P1.0.2
SINGLE CHANNEL INTEGRATED UART AND RS-232 TRANSCEIVER
1.0 PRODUCT DESCRIPTION
The XR19L200 interface converter consists of a full-functional UART with 16 bytes of transmit and receive
FIFO, a charge pump, two RS-232 drivers, two RS-232 receivers, and a sleep mode circuitry. It operates from
a single +3V to 5.5V supply at 250Kbps data rate, while meeting all EIA RS-232F specifications. Its feature set
is fully compatible to the XR16L580 device. Unlike the XR16L580, the modem signals are not CMOS/TTL
level, but conform to EIA/TIA 232 or RS-232 voltage levels. The configuration registers set is 16550 UART
compatible for control, status and data transfer. Also, the L200 has 16-bytes of transmit and receive FIFOs,
automatic Xon/Xoff and special character software flow control, transmit and receive FIFO trigger levels, and a
programmable baud rate generator with a prescaler of divide by 1 or 4. Additionally, the L200 includes the ACP
pin which the user can shut down the charge pump for the RS-232 drivers when the L200 is already in sleep
mode. The L200 is fabricated using an advanced CMOS process.
Enhanced Features
The L200 UART provides a solution that supports 16 bytes of transmit and receive FIFO memory. The L200 is
designed to work with low supply voltage and high performance data communication systems that require fast
data processing time. Increased performance is realized in the L200 by the transmit and receive FIFOs, FIFO
trigger level controls and automatic flow control mechanism. This allows the external processor to handle more
networking tasks within a given time. This increases the service interval giving the external CPU additional time
for other applications and reducing the overall UART interrupt servicing time.
Intel or Motorola Data Bus Interface
The L200 provides a host interface that supports Intel or Motorola microprocessor (CPU) data bus interface.
The Intel bus compatible interface allows direct interconnect to Intel compatible type of CPUs using IOR#,
IOW# and CS# inputs for data bus operation. The Motorola bus compatible interface instead uses the R/W#
and CS# signals for data bus transactions. See pin description section for details on all the control signals. The
Intel and Motorola bus interface selection is made through the pin, I/M#.
Data Rate
The L200 is capable of operation up to 250Kbps data rate using the 16X internal sampling clock rate. The
UART section can operate at much higher speeds, but the speed of the RS-232 transceiver is limited to
250Kbps beyond which the L200 cannot comply with the EIA/TIA-232 electrical characteristics. The device can
operate either with a crystal on pins XTAL1 and XTAL2, or external clock source on XTAL1 pin.
Internal Enhanced Register Sets
The L200 UART has a set of enhanced registers providing control and monitoring functions. Interrupt enable/
disable and status, FIFO enable/disable, selectable TX and RX FIFO trigger levels, automatic hardware/
software flow control enable/disable, programmable baud rates, modem interface controls and status, and
sleep mode are all standard features. Following a power on reset or an external reset (and operating in 16 or
Intel Mode), the registers defaults to the reset condition and is compatible with the XR16L580.
RS-232 Interface
The L200 includes RS-232 drivers/receivers for the TXD and RXD signals (If more modem input and output
signals are needed, see the XR19L220 and XR19L210). This feature eliminates the need for an external RS-
232 transceiver. The charge pump provides output voltages of +5V and -5V for its drivers over the 3.0V to 5.5V
VCC supply voltage. The serial output TX swings between -5V (inactive) and 5V (active) RS-232 voltage
levels. The serial input RX is an RS-232 receiver and can take any voltage swing from -15V to +15V. The
receiver is always active, even in Partial or Full Sleep modes. The RS-232 drivers guarantee a data rate of
250Kbps even when fully loaded with 3Kohm in parallel with 1000pF load. Also, the slew rate of the driver
output is internally limited to a maximum of 30V/us in order to meet the EIA-232F standard.
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