xr17v258 Exar Corporation, xr17v258 Datasheet - Page 32

• Manufacturer Part Number: xr17v258
• Description: 66mhz Pci Bus Octal Uart With Power Management Support
• Manufacturer: Exar Corporation

XR17V258
66MHZ PCI BUS OCTAL UART WITH POWER MANAGEMENT SUPPORT
The closest divisor that is obtainable in the V258 can be calculated using the following formula:
In the formulas above, please note that:
TRUNC (N) = Integer Part of N. For example, TRUNC (5.6) = 5.
ROUND (N) = N rounded towards the closest integer. For example, ROUND (7.3) = 7 and ROUND (9.9) = 10.
F
IGURE
ROUND( (Required Divisor - TRUNC (Required Divisor) )*16)/16 + TRUNC (Required Divisor), where
O
UTPUT
R
EQUIRED
10000
19200
25000
28800
38400
50000
57600
75000
R
2400
4800
9600
400
T
11. B
ATE
ABLE
D
ATA
AUD
12: T
XTAL1
XTAL2
R
D
YPICAL DATA RATES WITH A
ATE
DLD = ROUND ( (Required Divisor-TRUNC(Required Divisor) )*16)
16x Clock
(Decimal)
IVISOR FOR
52.0833
39.0625
26.0417
156.25
78.125
312.5
3750
625
150
60
30
20
G
ENERATOR
Crystal
Buffer
Osc/
DLL = TRUNC (Required Divisor) & 0xFF
DLM = TRUNC( Required Divisor) >> 8
O
BTAINABLE IN
Channels
To Other
312 8/16
156 4/16
78 2/16
52 1/16
39 1/16
26 1/16
D
V258
3750
IVISOR
625
150
60
30
20
Divide by 4
Divide by 1
Prescaler
Prescaler
24 MH
DLM P
V
ALUE
Z CRYSTAL OR EXTERNAL CLOCK AT
32
E
ROGRAM
2
1
0
0
0
0
0
0
0
0
0
(HEX)
MCR Bit-7=0
MCR Bit-7=1
(default)
DLL, DLM and DLD
Fractional Baud
Rate Generator
DLL P
V
ALUE
Registers
Logic
9C
3C
A6
4E
1E
1A
71
38
96
34
27
14
ROGRAM
(HEX)
DLD P
V
and Receiver
to Transmitter
ALUE
Rate Clock
16X or 8X
Sampling
ROGRAM
0
0
8
4
0
2
0
1
1
0
1
0
(HEX))
16X S
xr
AMPLING
D
ATA
R
ATE
0.04
0.08
REV. 1.0.0
0
0
0
0
0
0
0
0
0
0
E
RROR
(%)