DS2480B+ Maxim Integrated Products, DS2480B+ Datasheet - Page 2

• 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: Lead free / RoHS Compliant

DS2480B uses a unique protocol that merges data and control information without requiring control pins.
This approach maintains compatibility to off-the-shelf serial to wireless converters, allowing easy
realization of 1-Wire media jumpers. The various control functions of the DS2480B are optimized for 1-
Wire networks and support the special needs of all current 1-Wire devices including EPROM-based add-
only memories, EEPROM devices, and 1-Wire thermometers. See Application Note 192: Using the
DS2480B Serial 1-Wire Driver for detailed software examples.
DETAILED PIN DESCRIPTION
OVERVIEW
The DS2480B directly interfaces a 5V serial communication port with its lines TXD (transmit) and RXD
(receive) to a 1-Wire bus. In addition the device performs a speed conversion allowing the data rate at the
communication port to be different from the 1-Wire data rate. Several parameters relating to the 1-Wire
port and its timing as well as the communication speed at both the port and the 1-Wire bus are
configurable. The circuit to achieve these functions is outlined in the block diagram (see Figure 1).
The device gets its input data from the serial communication port of the host computer through pin TXD.
For compatibility with active-high as well as active-low systems, the incoming signal can be inverted by
means of the polarity input POL. The polarity chosen by hard-wiring the logic level of this pin is also
valid for the output pin RXD. If for minimizing the interface hardware an asymmetry between RXD and
TXD is desired, this can be achieved by setting the most significant bit of the speed control parameter to a
1 (see Configuration Parameter Value Codes). With the MS bit of the speed control set to 1, the polarity
at TXD is still selected by the logic level at POL, but the polarity at RXD will be the opposite of what the
logic level at POL specifies.
PIN
1
2
3
4
5
6
7
8
SYMBOL
GND
RXD
TXD
N.C.
POL
1-W
V
V
DD
PP
DESCRIPTION
Ground Pin. Common ground reference and ground return for 1-Wire bus
1-Wire Input/Output Pin. 1-Wire bus with slew-rate-controlled pulldown,
active pullup, ability to switch in V
in V
temperature conversion.
No Connection
Power Input Pin. Power supply for the chip and 1-Wire pullup voltage, 5V
±10%, must always be lower than or equal to V
V
EPROM Programming Voltage. 12V supply input for EPROM programming.
If EPROM programming is not required, connect this pin directly to the system’s
5V supply.
RXD/TXD Polarity Select. RXD/TXD polarity select; tied to GND for RS232
(12V or 5V) connection; tied to V
Serial Data from UART. Data input from host (inverted or true); maximum
voltage swing -0.3V to V
Serial Data to UART. Signal output to host; push-pull driver with CMOS
compatible levels; for true 12V RS232 systems an external level translator must
be provided.
PP
by a separate voltage regulator whenever possible.
DD
through a low-impedance path to program EEPROM, or perform a
DD
2 of 32
+ 0.3V; for logic thresholds see DC specifications.
DD
PP
for direct connection to UART chip.
to program EPROM, and ability to switch
PP
. V
DD
should be derived from