Datasheet

DS2480B
Maxim Integrated ........................................................................................................................................................................................... 12
Table 3. CONFIGURATION PARAMETER OVERVIEW
Parameter
Description
Configurable at
Default
Par. Code
Standard
Flexible
Overdrive
Reg./Flex.
Overdrive
Pulldown Slew Rate
Control
001 √ 15V/µs 15V/µs
Programming Pulse
Duration
010 √ √ √ 512µs 512µs
Strong Pullup Duration
011
√
√
√
524ms
524ms
Write-1 Low Time
100
√
8µs
1µs
Data Sample Offset and
Write 0 Recovery Time
101 √
3µs
3µs
1µs
3µs
RS232 Baud Rate
111
√
√
√
9.6kbps
9.6kbps
The numbers given for parameter 001 (Pulldown Slew Rate Control) are nominal values. They may vary
to some extent 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 the Controlled Edges section .
For the parameters 010 (Programming Pulse Duration) and 011 (Strong Pullup 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 pullup) that uses one of these parameters can be terminated by sending the command code F1h.
Termination is not possible if the device is in Data Mode.
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 changing the baud rate,
the DS2480B 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 Recovery Time) is given in the Timing Diagrams section later in this document.