XR16L2550IM-F Datasheet, PDF (10/44 Pages) Exar Corporation – LOW VOLTAGE DUART WITH 16-BYTE FIFO

XR16L2550
LOW VOLTAGE DUART WITH 16-BYTE FIFO
REV. 1.1.3
2.10 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 of up to 24
MHz. However, with an external clock input on XTAL1 pin and a 2K ohms pull-up resistor on XTAL2 pin (as
shown in Figure 5) it can extend its operation up to 64 MHz (4Mbps serial data rate) at room temperature and
5.0V.
FIGURE 5. EXTERNAL CLOCK CONNECTION FOR EXTENDED DATA RATE
External Clock
vcc
gnd
VCC
R1
2K
XTAL1
XTAL2
To obtain maximum data rate, it is necessary to use full rail swing on the clock input. See external clock
operating frequency over power supply voltage chart in Figure 6.
FIGURE 6. OPERATING FREQUENCY CHART. REQUIRES A 2K OHMS PULL-UP RESISTOR
ON XTAL2 PIN TO INCREASE OPERATING SPEED
Operating frequency for XR16L2550
with external clock and a 2K ohms
pull-up resistor on XTAL2 pin.
80
-40^oC
70
25^oC
85^oC
60
50
40
30
3.0 3.5 4.0 4.5 5.0 5.5
Suppy Voltage
10