DS2480B Datasheet, PDF (1/30 Pages) Dallas Semiconductor – Serial 1-Wire Line Driver with Load Sensor

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DS2480B
Serial 1-Wire^TM Line
Driver with Load Sensor
FEATURES
§ Universal, common-ground serial port to 1-
Wire™ line driver for MicroLAN applications
§ Works with all iButtons and MicroLAN-
compatible 1-Wire slave devices
§ Communicates at regular and Overdrive 1-
Wire speed and serial port data rates of 9600
(default), 19200, 57600 and 115200 bps
§ Supports 12V EPROM programming and stiff
5V pullup for crypto iButton, sensors and
EEPROM
§ Load sensor to terminate the stiff pullup as
the energy demand of the crypto iButton
drops
§ Self-calibrating time base with ± 5%
tolerance for serial and 1-Wire
communication
§ Slew rate controlled 1-Wire pulldown and
active pullup to accommodate long lines and
reduce radiation
§ User-selectable RXD/TXD polarity
minimizes component count when interfacing
to 5V based RS232 systems or directly to
UARTs
§ Programmable 1-Wire timing and driver
characteristics accommodate a wide range of
MicroLAN configurations at regular speed
§ Smart protocol combines data and control
information without requiring extra pins
§ Compatible with 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
PIN ASSIGNMENT
GND
1
8
RXD
1-W
2
NC
3
7
TXD
6
POL
VDD
4
5
VPP
8-Pin SOIC (150-mil)
PIN DESCRIPTION
GND
- Ground
1-W
- 1-Wire Input/Output
NC
- No Connection
VDD
- 4.5 to 5.5 Volts
VPP
- Optional EPROM
Programming Voltage
POL
- RXD/TXD Polarity Select
TXD
- Serial Data from UART
RXD
- Serial Data to UART
ORDERING INFORMATION
DS2480BS 8-pin SOIC
Note: The DS2480B will replace the DS2480
later in 1999. It is fully backward compatible to
software drivers that accept a 0 as well as a 1 for
bit 2 of the Reset-command response byte (see
page 7, Table 2)
DESCRIPTION
The DS2480B is a serial port to 1-Wire interface chip that supports regular and Overdrive speeds. It con-
nects directly to UARTs and 5V RS232 systems. Interfacing to RS232C (± 12V levels) requires a passive
clamping circuit 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 DS2480B can translate each character
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