DS2480
Serial
1–Wire
TM
DS2480
Line Driver
FEATURES
•
Universal, common–ground serial port to 1–Wire
TM
line driver for MicroLAN
TM
applications
PIN ASSIGNMENT
GND
1–W
NC
V
DD
1
2
3
4
8
7
6
5
RXD
TXD
POL
V
PP
•
Works
with all iButtons and MicroLAN–compatible
1–Wire slave devices
•
Communicates
•
Supports
at regular and Overdrive 1–Wire
speed and serial port data rates of 9600 (default),
19200, 57600 and 115200 bps
12V EPROM programming and stiff 5V
pull–up for Crypto iButton, sensors and EEPROM
time base with
±5%
tolerance for
serial and 1–Wire communication
rate controlled 1–Wire pull–down and active
pull–up to accommodate long lines and reduce radi-
ation
polarity minimizes com-
ponent count when interfacing to 5V based RS232
systems or directly to UARTs
tics accommodate a wide range of MicroLAN configu-
rations at regular speed
GND
1–W
NC
V
DD
V
PP
POL
TXD
RXD
8–PIN SOIC
(150 MIL)
PIN DESCRIPTION
Ground
1–Wire Input/Output
No Connection
4.5 to 5.5 Volts
Optional EPROM
Programming Voltage
RXD/TXD Polarity Select
Serial Data from UART
Serial Data to UART
•
Self–calibrating
•
Slew
•
User–selectable RXD/TXD
•
Programmable 1–Wire timing and driver characteris-
•
Smart protocol combines data and control information
without requiring extra pins
ORDERING INFORMATION
DS2480S
8–pin SOIC
•
Compatible to optical, IR and RF to RS232 converters
•
Low cost 8–pin SOIC surface mount package
•
Operates over 4.5V to 5.5V from –40°C to +85°C
DESCRIPTION
The DS2480 is a serial port to 1–Wire interface chip that
supports standard and Overdrive speeds. It connects
directly to UARTs and 5V RS232 systems. Interfacing to
RS232C (± 12V levels) requires a passive clamping cir-
cuit and one 5V to
±
12V level translator. Internal timers
relieve the host of the burden of generating the time–
critical 1–Wire communication waveforms. In contrast
to the DS9097(E) where a full character must be sent by
the host for each 1–Wire time slot, the DS2480 can
translate each character into eight 1–Wire time slots
thereby increasing the data throughput significantly. In
addition, the DS2480 can be set to communicate at four
different data rates including 115.2 kbps, 57.6 kbps and
19.2 kbps with 9.6 kbps being the power–on default.
Command codes received from the host’s crystal con-
trolled UART serve as a reference to continuously cali-
brate the on–chip timing generator. The DS2480 uses a
unique protocol that merges data and control informa-
tion without requiring control pins. This approach main-
tains compatibility to off–the–shelf serial to wireless
converters allowing easy realization of 1–Wire media
jumpers. The various control functions of the DS2480
are optimized for MicroLAN 1–Wire networks and sup-
port the special needs of all current 1–Wire devices
including the Crypto iButton, EPROM–based Add–Only
Memories, EEPROM devices and 1–Wire Thermome-
ters.
042498 1/26
DALLAS [ DALLAS SEMICONDUCTOR ]
