ADI DS2408

DS2408 General Description

The DS2408 stands as an 8-channel, configurable I/O 1-Wire chip. In this setup, the PIO outputs adopt an open-drain configuration, featuring an on resistance capped at 100Ω max. The system employs a robust channel-access communication protocol for PIO, ensuring error-free transitions in PIO output settings. A data-valid strobe output is also at your disposal, which can be harnessed to latch the logic states of PIO into external components like a D/A converter (DAC) or the data bus of a microcontroller.

Control over the DS2408's operation unfolds along the single-conductor 1-Wire bus. The device adheres to the standard Dallas Semiconductor 1-Wire protocol. Each DS2408 carries its own unalterable and unique 64-bit ROM registration number, etched into the chip during manufacturing. This registration number guarantees distinct identification and is employed to address the device in a multidrop 1-Wire network setting. It's worth noting that multiple DS2408 devices can coexist on a shared 1-Wire bus and can function independently of each other.

Moreover, the DS2408 boasts support for 1-Wire conditional search capability, triggered by conditions related to PIO or power-on-reset activity. The conditions that prompt participation in the conditional search are programmable.

As for the power supply, the DS2408 provides an optional VCC connection. In instances where an external supply is absent, the device derives power parasitically from the 1-Wire bus. However, in the presence of an external supply, the PIO states remain stable even when the 1-Wire bus power source is disconnected.

Additionally, the RSTZ signal configuration is flexible, capable of serving as either a hard-wired reset for the PIO output or as a strobe signal for external components, indicating the completion of a PIO write or read operation.

Features

Efficient Control of Eight Independent I/O Ports with a Single Micro Port Pin:

Gain command over eight separate Programmable I/O (PIO) channels featuring open-drain outputs.
The PIO pulldown transistor exhibits an impressive on-resistance of just 100Ω (maximum), while the off-resistance stands at a reliable 10MΩ (typical).
Individual activity latches capture asynchronous state changes occurring at PIO inputs, allowing for easy interrogation by the bus master.
A data-strobe output is included, facilitating synchronization of PIO logic states with external read/write circuitry.

Streamlined 1-Wire Interface for Cost-Effective and Simple Integration:

The DS2408 incorporates a minimalist 1-Wire interface, effectively reducing both cost and interface complexity.
It boasts a built-in multidrop controller, ensuring seamless compatibility with other 1-Wire® network products.
Support for the 1-Wire conditional search command, with the response being controlled by programmable PIO conditions.
Each DS2408 is equipped with a unique 64-bit registration number, factory-lasered to guarantee error-free device selection and absolute part identity.
Communication with the host is achieved using a single digital signal, capable of operating at either 15.3kbps or 100kbps.

Robust Performance Across Wide Voltage and Temperature Ranges:

The DS2408 operates reliably within a wide voltage range of 2.8V to 5.25V.
It is designed to endure challenging environmental conditions, boasting an industrial temperature range of -40°C to +85°C.
These features collectively make the DS2408 a versatile and reliable solution for applications requiring control and monitoring of multiple I/O channels with simplified interfacing and robust performance.

Application

Port Expander for Microcontrollers: The DS2408 can be employed as a port expander, allowing microcontrollers with limited I/O pins to interface with multiple external devices or sensors. This is especially useful in projects where additional I/O pins are required.

Remote Multichannel Sensor/Actuator: It can serve as a remote sensor and actuator interface, enabling the collection of data from multiple sensors distributed over a wide area and the control of various actuators remotely. This makes it suitable for applications in home automation, industrial control systems, and environmental monitoring.

Communication and Control Unit of a Microterminal: In microterminal or control applications, the DS2408 can be used to manage and control peripheral devices, facilitating communication between the microterminal and external components such as displays, keypads, or sensors.

Network Interface for a Microcontroller: It can function as a network interface for a microcontroller, allowing the microcontroller to connect to a network and communicate with other devices or systems. This is particularly useful in applications that require network connectivity, such as IoT (Internet of Things) devices.

Specifications