![](http://datasheet.mmic.net.cn/Exar-Corporation/XR16V2551IL-F_datasheet_100050/XR16V2551IL-F_13.png)
TABLE 6: TYPICAL DATA RATES WITH A 24 MHZ CRYSTAL OR EXTERNAL CLOCK AT 16X SAMPLING
Required
Output Data
Rate
DIVISOR FOR
16x Clock
(Decimal)
DIVISOR
OBTAINABLE IN
V2551
DLM PROGRAM
VALUE (HEX)
DLL PROGRAM
VALUE (HEX)
DLD PROGRAM
VALUE (HEX)
DATA ERROR
RATE (%)
400
3750
E
A6
0
2400
625
2
71
0
4800
312.5
312 8/16
1
38
8
0
9600
156.25
156 4/16
0
9C
4
0
10000
150
0
96
0
19200
78.125
78 2/16
0
4E
2
0
25000
60
0
3C
0
28800
52.0833
52 1/16
0
34
1
0.04
38400
39.0625
39 1/16
0
27
1
0
50000
30
0
1E
0
57600
26.0417
26 1/16
0
1A
1
0.08
75000
20
0
14
0
100000
15
0
F
0
115200
13.0208
13
0
D
0
0.16
153600
9.7656
9 12/16
0
9
C
0.16
200000
7.5
7 8/16
0
7
8
0
225000
6.6667
6 11/16
0
6
B
0.31
230400
6.5104
6 8/16
0
6
8
0.16
250000
6
0
6
0
300000
5
0
5
0
400000
3.75
3 12/16
0
3
C
0
460800
3.2552
3 4/16
0
3
4
0.16
500000
3
0
3
0
750000
2
0
2
0
921600
1.6276
1 10/16
0
1
A
0.16
1000000
1.5
1 8/16
0
1
8
0
XR16V2551
13
REV. 1.0.3
HIGH PERFORMANCE DUART WITH 16-BYTE FIFO AND POWERSAVE FEATURE
2.11
Transmitter
The transmitter section comprises of an 8-bit Transmit Shift Register (TSR) and 16 bytes of FIFO which
includes a byte-wide Transmit Holding Register (THR). TSR shifts out every data bit with the 16X/8X/4X
internal clock. A bit time is 16/8/4 clock periods (see DLD[5:4]). The transmitter sends the start-bit followed by
the number of data bits, inserts the proper parity-bit if enabled, and adds the stop-bit(s). The status of the FIFO
and TSR are reported in the Line Status Register (LSR bit-5 and bit-6).