Exar Corporation 48720 Kato Road, Fremont CA, 94538 (510) 668-7000 FAX (510) 668-7017 www.exar.com
XR19L202
TWO CHANNEL INTEGRATED UART AND RS-232 TRANSCEIVER
JULY 2007
REV. 1.0.1
GENERAL DESCRIPTION
The XR19L202 (L202) is a highly integrated device that
combines
a
full-featured
two
channel
Universal
Asynchronous Receiver and Transmitter (UART) and RS-
232 transceivers. The L202 is designed to operate with a
single 3.3V or 5V power supply. The L202 is fully compliant
with EIA/TIA-232-F Standards from a +3.3V to +5.5V power
supply. The device operates at 1 Mbps data rate with worst
case 3K ohms load. Both RS-232 driver outputs and
receiver inputs can operate in harsh electrical environments
of +/-15V without damage and can survive multiple +/-15kV
ESD on the RS-232 lines, while maintaining RS-232 output
levels.
The L202 operates in four different modes: Active, Partial
Sleep, Full Sleep and Power-Save. Each mode can be
invoked via hardware or software. Upon power-up, the
L202 is in the Active mode where the UART and RS-232
transceiver function normally. In the Partial Sleep mode, the
internal crystal oscillator of the UART or charge pump of the
RS-232 transceiver is turned off. In Full Sleep mode, both
the crystal oscillator and the charge pump are turned off.
While the UART is in the Sleep mode, the Power-Save
mode isolates the core logic from the control signals (chip
select, read/write strobes, address and data bus lines) to
minimize the power consumption. The RS-232 receivers
remain active in any of these four modes.
APPLICATIONS
Battery-Powered Equipment
Handheld and Mobile Devices
Handheld Terminals
Industrial Peripheral Interfaces
Point-of-Sale (POS) Systems
FEATURES
Meets true EIA/TIA-232-F Standards from +3.3V to +5.5V
operation
Up to 1 Mbps data transmission rate
45us sleep mode exit (charge pump to full power)
ESD protection for RS-232 I/O pins at
■ +/-15kV - Human Body Model
■ +/-15kV - IEC 61000-4-2, Air-Gap Discharge
■ +/- 8kV - IEC 61000-4-2, Contact Discharge
Software compatible with industry standard 16550 UART
Intel/Motorola bus select
Complete modem interface
Sleep and Power-save modes to conserve battery power
Wake-up interrupt upon exiting low power modes
FIGURE 1. BLOCK DIAGRAM
XR19L202
UART
RS-232 Transceiver
Int
e
lor
M
o
torola
B
u
s
I
n
terface
PwrSave
A2:A0
D7:D0
IOR#
IOW # (R/W#)
CSA# (CS#)
CSB#
INTA (IRQ#)
INTB
RESET (RESET#)
I/M#
Crystal
Osc/Buffer
XT
A
L
1
XT
A
L
2
BRG
64 Byte
TX & RX
FIFO
Modem
I/Os
UART
Registers
TXA
RXA
Charge Pump
TXDA
5K
RXDA
AC
P
C2+
C2-
C1+
C1-
VCC
(3.3
to
5.5V)
*5 V Tolerant
Inputs
VREF+
VREF-
GN
D
FA
ST
R_EN
Channel B
Channel A
TXB
RXB
Channel B
Transceiver
Ch A Transceiver
RXBSEL
TXDB
TXB
RXDB
RXB
(See Figure 6)