XR19L400 Datasheet, PDF (1/45 Pages) Exar Corporation – SINGLE CHANNEL INTEGRATED UART AND RS-485 TRANSCEIVER

PRELIMINARY
XR19L400
SINGLE CHANNEL INTEGRATED UART AND RS-485 TRANSCEIVER
APRIL 2007
REV. P1.0.0
GENERAL DESCRIPTION
The XR19L400 (L400) is a highly integrated device that
combines a full-featured single channel Universal
Asynchronous Receiver and Transmitter (UART) and RS-
485 transceivers. The L400 is designed to operate with a
3.3V to 5V power supply. The L400 is fully compliant with
RS-485 Standards.
The L400 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
L400 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 from +3.0V to +5.5V
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 61000-4-2, 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#)
CS# (CS#)
INT (IRQ#)
RESET (RESET#)
I/M#
HALF/FULL#
*5 V Tolerant
Inputs
Crystal
Osc/Buffer
BRG
64 Byte
TX FIFO
TX
Charge Pump
UART
64 Byte
RX FIFO
Modem
I/Os
RX
VCC33
CTS#
DSR#
RI#
CD#
RS-485 Transceiver
XR19L400
TX+
TX-
RX+
RX-
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com