XR16L2450IJ-F Exar Corporation, XR16L2450IJ-F Datasheet - Page 8

• Manufacturer Part Number: XR16L2450IJ-F
• Description: 2.25 To 5.5V W/ 5V TOLERANT DUART
• Manufacturer: Exar Corporation

Specifications of XR16L2450IJ-F

• Features: *
• Number Of Channels: 2, DUART
• Fifo's: 1 Byte
• Protocol: RS232
• Voltage - Supply: 2.25 V ~ 5.5 V
• With False Start Bit Detection: Yes
• With Modem Control: Yes
• With Cmos: Yes
• Mounting Type: Surface Mount
• Package / Case: 44-LCC (J-Lead)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

xr
XR16L2450
2.25V TO 5.5V DUART
REV. 1.1.1
F
4. T
IGURE
YPICAL OSCILLATOR CONNECTIONS
XTAL1
XTAL2
R1
0-120
Ω
(Optional)
R2
500 Κ Ω − 1 Μ Ω
1.8432 MHz
Y1
to
24 MHz
C1
C2
22-47 pF
22-47 pF
The on-chip oscillator is designed to use an industry standard microprocessor crystal (parallel resonant,
fundamental frequency with 10-22 pF capacitance load, ESR of 20-120 ohms and 100 ppm frequency
tolerance) connected externally between the XTAL1 and XTAL2 pins (see
Figure
4), with an external 500 kΩ to
1 MΩ resistor across it. Alternatively, an external clock can be connected to the XTAL1 pin to clock the internal
baud rate generator for standard or custom rates. Typical oscillator connections are shown in
Figure
4. For
further reading on oscillator circuit please see application note DAN108 on EXAR’s web site.
2.9
Programmable Baud Rate Generator
A single baud rate generator is provided for the transmitter and receiver, allowing independent TX/RX channel
control. The programmable Baud Rate Generator is capable of operating with a crystal frequency or external
clock of up to 24 MHz.
The L2450 divides the basic external clock by 16. The basic 16X clock provides table rates to support standard
and custom applications using the same system design. The Baud Rate Generator divides the input 16X clock
16
by any divisor from 1 to 2
-1. The rate table is configured via the DLL and DLM internal register functions.
Customized Baud Rates can be achieved by selecting the proper divisor values for the MSB and LSB sections
of baud rate generator.
Table 3
shows the standard data rates available with a 14.7456 MHz crystal or external clock at 16X sampling
rate. When using a non-standard frequency crystal or external clock, the divisor value can be calculated for
DLL/DLM with the following equation.
divisor (decimal) = (XTAL1 clock frequency) / (serial data rate x 16)
8