xr17d152im Exar Corporation, xr17d152im Datasheet - Page 26

• Manufacturer Part Number: xr17d152im
• Description: Universal 3.3v And 5v Pci Bus Dual Uart
• Manufacturer: Exar Corporation

XR17D152
UNIVERSAL (3.3V AND 5V) PCI BUS DUAL UART
Programming the Baud Rate Generator Registers DLM and DLL provides the capability for selecting the
operating data rate.
clock at 16X clock rate. At 8X sampling rate, these data rates would double. When using a non-standard data
rate crystal or external clock, the divisor value can be calculated with the following equation(s).
O
divisor (decimal) = (XTAL1 clock frequency / prescaler) / (serial data rate x 16),
divisor (decimal) = (XTAL1 clock frequency / prescaler) / (serial data rate x 8),
UTPUT
MCR Bit-7=1
T
115.2k
230.4k
ABLE
19.2k
38.4k
57.6k
1200
2400
4800
9600
100
600
Data Rate
9: T
F
IGURE
YPICAL DATA RATES WITH A
XTAL1
XTAL2
O
UTPUT
Table 9
11. B
MCR Bit-7=0
153.6k
230.4k
460.8k
921.6k
19.2k
38.4k
76.8k
2400
4800
9600
400
Data Rate
AUD
shows the standard data rates available with a 14.7456 MHz crystal or external
Crystal
Buffer
R
Osc/
ATE
Clock (Decimal)
D
G
To Channel 1
IVISOR FOR
ENERATOR
2304
14.7456 MH
384
192
96
48
24
12
6
4
2
1
Divide by 4
Divide by 1
Prescaler
Prescaler
16x
D
26
IVISOR FOR
Z CRYSTAL OR EXTERNAL CLOCK AT
Clock (HEX)
MCR Bit-7=0
MCR Bit-7=1
(default)
900
180
C0
0C
60
30
18
06
04
02
01
16x
Baud Rate
DLL and DLM
Generator
Registers
Logic
DLM P
V
ALUE
WITH
WITH
09
01
00
00
00
00
00
00
00
00
00
ROGRAM
8XMODE [1:0]
(HEX)
8XMODE [1:0]
Rate Clock to
and Receiver
Transmitter
16X or 8X
Sampling
DLL P
V
ALUE
C0
0C
00
80
60
30
18
06
04
02
01
16X S
ROGRAM
IS
(HEX)
IS
áç
áç
áç
áç
1
0
AMPLING
D
E
ATA
REV. 1.2.0
RROR
0
0
0
0
0
0
0
0
0
0
0
R
ATE
(%)