19-5702; 12/10
DS2408
1-Wire 8-Channel Addressable Switch
www.maxim-ic.com
FEATURES
PIN CONFIGURATION
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Eight Channels of Programmable I/O with
Open-Drain Outputs
On-Resistance of PIO Pulldown Transistor
100Ω (max); Off-Resistance 10MΩ (typ)
Individual Activity Latches Capture
Asynchronous State Changes at PIO Inputs for
Interrogation by the Bus Master
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Data-Strobe Output to Synchronize PIO Logic
States to External Read/Write Circuitry
Built-in Multidrop Controller Ensures
Compatibility with Other Dallas Semiconductor
1-Wire® Net Products
150-mil SO
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Supports 1-Wire Conditional Search Command
with Response Controlled by Programmable
PIO Conditions
Unique Factory-Lasered 64-Bit Registration
Number Ensures Error-Free Device Selection
and Absolute Part Identity
Communicates to Host with a Single Digital
Signal at 15.3kbps or 100kbps using 1-Wire
Protocol
Operating Range: 2.8V to 5.25V, -40°C to
+85°C
ORDERING INFORMATION
PART
TEMP RANGE PIN-PACKAGE
DS2408S+
-40°C to +85°C
16 SO
16 SO
DS2408S+T&R -40°C to +85°C
+Denotes a lead(Pb)-free package.
T&R = Tape and reel.
DESCRIPTION
The DS2408 is an 8-channel, programmable I/O 1-Wire chip. PIO outputs are configured as open-drain and
provide an on resistance of 100Ω max. A robust PIO channel-access communication protocol ensures that PIO
output-setting changes occur error-free. A data-valid strobe output can be used to latch PIO logic states into
external circuitry such as a D/A converter (DAC) or microcontroller data bus.
DS2408 operation is controlled over the single-conductor 1-Wire bus. Device communication follows the
standard Dallas Semiconductor 1-Wire protocol. Each DS2408 has its own unalterable and unique 64-bit
ROM registration number that is factory lasered into the chip. The registration number guarantees unique
identification and is used to address the device in a multidrop 1-Wire net environment. Multiple DS2408
devices can reside on a common 1-Wire bus and can operate independently of each other. The DS2408 also
supports 1-Wire conditional search capability based on PIO conditions or power-on-reset activity; the
conditions to cause participation in the conditional search are programmable. The DS2408 has an optional VCC
supply connection. When an external supply is absent, device power is supplied parasitically from the 1-Wire
bus. When an external supply is present, PIO states are maintained in the absence of the 1-Wire bus power
source. The RSTZ signal is configurable to serve as either a hard-wired reset for the PIO output or as a strobe
for external circuitry to indicate that a PIO write or PIO read has completed.
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
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