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.
Key Features
Applications/Uses
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
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
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
Industrial Control Instrumentation Test and Measurement Rack Based Systems Such as Central Office Switches, Wireless Base Stations, and PBXs
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