xr16c2852ij Exar Corporation, xr16c2852ij Datasheet - Page 10

• Manufacturer Part Number: xr16c2852ij
• Description: 2.97v To 5.5v Dual Uart With 128-byte Fifos
• Manufacturer: Exar Corporation

XR16C2852
2.97V TO 5.5V DUAL UART WITH 128-BYTE FIFOS
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 100ppm frequency
tolerance) connected externally between the XTAL1 and XTAL2 pins (see
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
application note DAN108 on EXAR’s web site.
A single Baud Rate Generator (BRG) 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
temperature and 5.0V.
F
Each UART also has their own prescaler along with the BRG. The prescaler is controlled by a software bit in
the MCR register. The MCR register bit-7 sets the prescaler to divide the input crystal or external clock by 1 or
4. The clock output of the prescaler goes to the BRG. The BRG further divides this clock by a programmable
2.10
IGURE
5. E
Programmable Baud Rate Generator
XTERNAL
Figure
C
LOCK
5) it can extend its operation up to 50 MHz (3.125 Mbps serial data rate) at room
C
ONNECTION FOR
F
IGURE
vcc
gnd
4. T
External Clock
22-47 pF
YPICAL OSCILLATOR CONNECTIONS
XTAL1
C1
E
Figure
XTENDED
R1
2K
500 ΚΩ − 1 ΜΩ
VCC
4. For further reading on oscillator circuit please see
10
R2
22-47 pF
XTAL2
C2
Y1
D
ATA
XTAL1
XTAL2
1.8432 MHz
(Optional)
0-120 Ω
24 MHz
R1
R
to
ATE
Figure
4). Alternatively, an external
xr
REV. 2.1.1