XR19L402 Datasheet, PDF (1/50 Pages) Exar Corporation – TWO CHANNEL INTEGRATED UART AND RS-485 TRANSCEIVER

XR19L402
TWO CHANNEL INTEGRATED UART AND RS-485 TRANSCEIVER
JUNE 2007
REV. 1.0.0
GENERAL DESCRIPTION
The XR19L402 (L402) is a highly integrated device that
combines a full-featured two channel Universal
Asynchronous Receiver and Transmitter (UART) and RS-
485 transceivers. The L402 is designed to operate with a
single 3.3V or 5V power supply. The L402 is fully compliant
with RS-485 Standards.
The L402 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
L402 is in the Active mode where the UART and RS-485
transceiver function normally. In the Partial Sleep mode, the
internal crystal oscillator of the UART or charge pump of the
RS-485 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-485 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 RS-485 Standards at 3.3V or 5V operation
• Up to 8 Mbps data transmission rate
• 45us sleep mode exit (charge pump to full power)
• ESD protection for RS-485 I/O pins at
■ +/-15kV - Human Body Model
■ +/- 8kV - IEC 1000-4-2, Contact Discharge
■ +/- 15kV - IEC 61000-4-2, Air-Gap 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
PwrSave
A2:A0
D7:D0
IOR#
IOW# (R/W#)
CSA# (CS#)
CSB#
INTA (IRQ#)
INTB
RESET (RESET#)
I/M#
TEST_EN
HALF/FULLA#
HALF/FULLB#
RXBSEL
*5 V Tolerant
Inputs
Crystal
Osc/Buffer
BRG
64 Byte
TX FIFO
TXA
Charge Pump
64 Byte
RX FIFO
Modem
I/Os
Channel A
Channel B
( Similar to
ChannelA )
RXA
VCC33
CTSA#
DSRA#
RIA#
CDA#
RS-485 Transceiver
TXB
RXB
UART
TXA+
TXA-
RXA+
RXA-
TXB+
TXB-
RXB+
RXB-
TXB
RXB
XR19L402
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com