DS2480B

into eight 1-Wire time slots, thereby increasing the data throughput significantly. In addition, the

DS2480B can be set to communicate at four different data rates, including 115.2kbps, 57.6kbps, and

19.2kbps, with 9.6kbps being the power-on default. Command codes received from the host’s crystal

controlled UART serve as a reference to continuously calibrate the on-chip timing generator. The

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

PIN

SYMBOL

DESCRIPTION

1

GND

Ground Pin. Common ground reference and ground return for 1-Wire bus

2

1-W

1-Wire Input/Output Pin. 1-Wire bus with slew-rate-controlled pulldown,

temperature conversion.

3

N.C.

No Connection

4

Power Input Pin. Power supply for the chip and 1-Wire pullup voltage, 5V

5

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.

6

POL

RXD/TXD Polarity Select. RXD/TXD polarity select; tied to GND for RS232

7

TXD

Serial Data from UART. Data input from host (inverted or true); maximum

8

RXD

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.

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.

Maxim Integrated ............................................................................................................................................................................................. 2