19-4874; 8/09
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DS9097U
www.maxim-ic.com
FEATURES
True-Ground Interface to an RS232 COM Port for
Reading and Writing 1-Wire® Devices
Works with Bipolar as well as Unipolar Logic
Signals
Compatible to COM port of (±)5V to (±)12V (DB-9
Version Only) or (±)6V to (±)12V (DB-25 Version)
Supports Reading and Writing at Regular and
Overdrive Speeds
Provides Strong Pullup to 5V for Temperature-,
Crypto-, and EEPROM 1-Wire devices
Programs 1-Wire EPROM Devices (DB-25
Version with External 12V Power Supply Only)
Communicates at Data Rates of 9.6 (default),
19.2, 57.6, and 115.2kbps
Standard DB-9 or DB-25 Female Connector and
6-lead RJ-11 Connector for Easy Attachment of
Standard 1-Wire Cables and Probes
Includes DS2502 Identification Chip (DS9097U-
009 only)
PIN ASSIGNMENT
DB-25: TXD (2), RXD (3), DTR (20), RTS (4), PC-
Ground (7); all other pins not connected
DB-9: TXD (3), RXD (2), DTR (4), RTS (7),
PC-Ground (5); all other pins not connected
NOTES:
* The external supply for the DS9097U-E25 must
provide well-regulated 12V @ 10mA minimum,
center = GND, outer ring = V+ (Newark Electronics
Stock No. 84F2081, Allied Electronics Stock No.
928-9895, Stancor Model STA-300R, or equivalent)
* The color of the DS9097U plastic case may vary.
ORDERING INFORMATION
DS9097U-009# DB-9, with DS2502 ID Chip
DS9097U-S09# DB-9, no ID chip
DS9097U-E25# DB-25, with EPROM Write
# Denotes an RoHS-compliant device that may include lead(Pb)
that is exempt under the RoHS requirements.
PACKAGE OUTLINE
DB-09 version
SIDE VIEW REAR VIEW
RJ-11 pin 1
DB-25 version
RJ-11 pin 1
SIDE VIEW REAR VIEW
+ contact
- contact
2.1mm
power jack
SCHEMATIC (for illustration)
DB-9 version
6
4
RTS
DTR
RXD
TXD
GND
RS232
COM Port
5V
Reg.
DS
2480B
1
7
8
5
2
RJ-11
1-W
GND
6
5
4
3
2
1
ID
Chip
DS9097U-009
only
DB-25 version
6
4
RTS
DTR
RXD
TXD
GND
RS232
COM Port
5V
Reg.
DS
2480B
1
7
8
5
2
RJ-11
1-W
GND
6
5
4
3
2
1
Power Jack
9V
Universal 1-Wire COM Port Adapte
r
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
DS9097U
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DESCRIPTION
The DS9097U is a sophisticated RS232 to 1-Wire adapter, which performs RS232 level conversion and actively
generates the 1-Wire communication signals. Together with an adequate TMEX software driver, it enables an IBM-
compatible PC to directly communicate with any 1-Wire device connected to the adapter's RJ-11 port. The DB-9
version reads and writes any non-EPROM 1-Wire device. To write to EPROM devices, the DB-25 version with
external power supply is required.
All DS9097U adapters are based on the DS2480B Serial 1-Wire Line Driver chip and therefore are not a plug-in
replacement for the DS9097 or DS9097E. The RXD/TXD Polarity Select input of the DS2480B is tied to VDD (non-
inverting). Free software drivers can be downloaded from http://www.ibutton.com/software/tmex/index.html.
The DS9097U communicates with 1-Wire devices at regular speed as well as Overdrive speed. The serial port
must support a data transmission rate of 9600bps. Under software control, the adapter can be set up for RS232
data rates of 19200, 57600, and 115200bps. The two higher rates are recommended for communication at
Overdrive speed with Overdrive capable devices. Since the DS9097U operates in a byte mode, every data byte
received from the RS232 port generates eight time slots on the 1-Wire line. At 19200bps data rate the DS9097U-
E25 is already faster than the DS9097 (E) at 115200bps.
Note that there are some COM ports that use signal levels of less than () 5V. The DB-9 versions of this adapter
will not work with such ports. The DS9097U-E25 adapter, however, will function in most cases if external power is
supplied. Without EPROM programming, the external power may be anywhere in the range of 6V to 9V. For
EPROM programming the voltage must be at 12V in any case. Before using an externally powered DS9097U-E25
with a COM port of less than () 5V check whether the COM port will not be damaged by 5V on its RXD input.
DS9097U
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REVISION HISTORY
REVISION
DATE DESCRIPTION PAGES
CHANGED
8/09 Added the # sign to all the part numbers in the Ordering Information table. 1
