DS2480 Dallas Semiconducotr, DS2480 Datasheet - Page 10

• Manufacturer Part Number: DS2480
• Description: Serial 1.Wire Line Driver
• Manufacturer: Dallas Semiconducotr

CONFIGURATION COMMAND OVERVIEW Table 3
The numbers given for parameter 001 (Pull–Down Slew
Rate Control) are nominal values. They may vary as
specified in the Electrical Characteristics section and
are almost independent of the load on the 1–Wire bus.
Information on how to select the optimum value of this
parameter is given in section “Controlled Edges”.
For the parameters 010 (Programming Pulse Duration)
and 011 (Strong Pull–Up Duration) one may select
indefinite duration. This value, however, should only be
selected if one is not going to switch the device to Data
Mode. As long as the device stays in Command Mode,
any pulse function (programming or strong pull–up) that
uses one of these parameters can be terminated by
sending the command code F1h. Termination is not pos-
sible if the device is in Data Mode.
CONFIGURATION PARAMETER VALUE CODES Table 4
DS2480
042498 10/26
Pull–Down Slew Rate Control
Programming Pulse Duration
Strong Pull–up Duration
Write 1 low time
Data Sample Offset and
Write 0 Recovery Time
RS232 Baud Rate
001 (PDSRC)
010 (PPD)
011 (SPUD)
100 (W1LT)
101 (DSO/W0RT)
111 (RBR)
P
Parameter Description
P
Parameter Code
D
C d
i i
P
Par. Code
001
010
011
100
101
111
16.4
C d
000
9.6
15
32
8
3
65.5
19.2
001
2.2
Regular Flexible Overdrive
64
9
4
1.65
57.6
Configurable at
010
128
131
10
5
Parameter 111 (RS232 Baud Rate) has two functions. It
selects the baud rate and allows inversion of the signal
at the RXD pin. Using one of the value codes 100 to 111
will set the polarity at RXD to the opposite of what is
defined by the logic level at the POL pin (asymmetry bit,
see Figure 1). This may reduce the component count in
some applications of the device. Note that when chang-
ing the baud rate, the DS2480 will send the command
response byte at the new data rate.
A short explanation on the use of parameters 100 (Write
1 low time) and 101 (Data Sample Offset/Write 0 Recov-
ery Time) is given in the section “Timing Diagrams” later
in this document. The parameter code 110 is reserved
for future extensions; one should not change the value
code from its default setting.
115.2
Value Codes
1.37
011
256
262
11
6
100
512
524
1.1
9.6
12
7
1024
1048
0.83
19.2
101
13
8
Reg./Flex.
9.6k bits/s
15 V/ s
524 ms
512 s
8 s
3 s
3 s
2048
2096
57.6
110
0.7
14
9
Default
115.2
0.55
111
15
10
Overdrive
9.6k bits/s
15 V/ s
524 ms
512 s
1 s
1 s
3 s
kbits/s
U i
Unit
V/ s
ms
s
s
s