Analog Devices Inc./Maxim Integrated DS2490S

Overview

DS2490S from Maxim Integrated is a USB-to-1-Wire bridge IC that enables full-speed 12Mbps USB host communication with 1-Wire buses, supports regular/overdrive/flexible timing modes, provides active slew-rate-controlled 1-Wire edge shaping, and delivers stiff 5V strong pullup for EEPROMs, sensors, and iButton® devices in industrial and embedded systems.

For engineers reviewing the DS2490S datasheet, DS2490S pinout, DS2490S application, or DS2490S equivalent, key selection criteria include USB remote wake-up capability, programmable pulldown slew rate (target 1V/µs for 300m networks), crystal-based 12MHz timebase for precision waveform generation, and support for stiff 5V pullup on long or loaded 1-Wire networks.

Technical Context

The DS2490S integrates a USB 1.1-compliant transceiver, USB device controller, and dedicated 1-Wire interface controller with active edge shaping circuitry. It uses an external 12.0MHz crystal (XI/XO) to generate precise 1-Wire timing, enabling accurate reset/presence detection and data slot waveforms across all speed modes.

Its 1-Wire I/O features programmable parameters including Write-1 low time (4–11µs), data sample offset (10–24µs), strong pullup duration (predefined or infinite), and pulldown slew rate (adjustable via MODE_CMD). USB remote wake-up is supported but disabled at power-on default and requires explicit host enablement.

Key Specifications

Pinout & Package

DS2490S is housed in a 24-pin SOIC package (300-mil width), RoHS-compliant and lead-free. Pin functions are validated per Maxim's DS2490 datasheet Rev 19-4993.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar USB-to-1-Wire bridge applications.

Compared with DS9490R, DS2490S offers full layout control, thermal management, and custom 1-Wire network design; compared with TUSB3410, DS2490S eliminates firmware timing-critical code and external analog components, delivering turnkey 1-Wire compliance with crystal-locked accuracy.

Availability

DS2490S is available at Aetrix Electronics and suitable for industrial asset tagging, secure access control, environmental sensor networks, and legacy system modernization requiring stable component supply and long-term lifecycle support.

Supply support for DS2490S includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs high-performance analog and mixed-signal ICs for industrial, communications, and computing applications.

The DS2490S belongs to Maxim's 1-Wire interface product line, engineered specifically to offload precise 1-Wire timing, edge control, and USB protocol handling from host processors in embedded and PC-connected systems.

FAQ

What is the primary function of the DS2490S in a USB-to-1-Wire system?

The DS2490S serves as a dedicated hardware bridge that translates USB host commands into precisely timed 1-Wire waveforms. It handles all low-level 1-Wire protocol requirements - including reset/presence detection, data slot timing, active edge shaping, and 5V strong pullup - freeing the host CPU from real-time timing constraints. This makes DS2490S essential for reliable communication with Dallas Semiconductor 1-Wire devices such as iButton® tokens, temperature sensors, and crypto memories.

Does the DS2490S require an external crystal, and why?

Yes, the DS2490S requires an external 12.0MHz fundamental-mode parallel-resonant crystal connected between XI and XO pins. This crystal provides the timebase for all 1-Wire timing functions - including reset pulse widths, data slot durations, and presence sampling offsets - ensuring accuracy across voltage and temperature variations. Without this crystal, DS2490S cannot generate compliant 1-Wire waveforms; a CMOS clock source may substitute but must meet strict jitter and stability specs.

How does the DS2490S support long 1-Wire networks up to 300 meters?

The DS2490S supports long 1-Wire networks through programmable pulldown slew rate control (target 1V/µs), flexible timing mode with adjustable Write-1 low time and data sample offset, and active rising-edge pullup that reduces rise time versus passive resistors. These features collectively minimize ringing, improve noise margin, and ensure reliable signal recovery on highly capacitive lines - validated in Maxim's documentation for networks up to 300m using appropriate cabling and termination.

Can the DS2490S wake up a suspended USB host system?

Yes, the DS2490S supports USB remote wake-up: when enabled via vendor-specific command, it asserts resume signaling on the USB bus upon detecting 1-Wire device attachment or activity. This feature is disabled by default at power-on and must be explicitly activated by host software. Once enabled, DS2490S allows battery-powered or energy-efficient hosts to remain in suspend mode until a 1-Wire event triggers wake-up - critical for access control and sensor polling applications.

What are the power supply requirements for the DS2490S?

The DS2490S requires three distinct supplies: VB = 3.3V ±10% for USB interface (derived from USB VBUS), and VD = 5.0V ±10% for digital logic and 1-Wire functions. VD2 is a second VD pin that must be externally tied to VD - it is not internally connected. All supplies require local ceramic decoupling (e.g., 0.1µF) near the respective pins. GND serves as the common reference for all domains.