DS2480B Maxim Integrated Products, DS2480B Datasheet - Page 12

• Manufacturer Part Number: DS2480B
• Description: IC LINE DRVR W/SENSOR 1-W 8-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Line Driver, Transmitterr

Specifications of DS2480B

• Number Of Drivers/receivers: 1/0
• Protocol: RS232
• Voltage - Supply: 4.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Table 3. CONFIGURATION PARAMETER OVERVIEW
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 .
Parameter 110 (Load Sensor Threshold) has been implemented in order to more efficiently support the
high current demand of the crypto iButton. The load sensor is only active if “dynamic” (value code 110)
for the Strong Pullup Duration (parameter 011) has been selected. The nominal and default value for the
load sensor threshold is 3.0mA with a tolerance band of -25% to +80%. The sensor threshold should be
left at its default value; changes should only be made to compensate for tolerances. Dynamic duration
should only be used when operating crypto iButtons and not for gang-programming 1-Wire EEPROMs or
measuring temperature with multiple temperature sensors converting simultaneously.
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.
Pulldown Slew Rate
Control
Programming Pulse
Duration
Strong Pullup Duration
Write-1 Low Time
Data Sample Offset and
Write 0 Recovery Time
Load Sensor Threshold
RS232 Baud Rate
Parameter Description
Par. Code Regular
001
010
011
100
101
110
111
√
√
√
√
12 of 31
Configurable at
Flexible
√
√
√
√
√
√
√
Overdrive
√
√
√
√
Reg./Flex.
9.6kbps
15V/µs
524ms
512µs
3mA
8µs
3µs
3µs
Default
Overdrive
9.6kbps
15V/µs
524ms
512µs
3mA
1µs
1µs
3µs