Analog Devices Inc./Maxim Integrated DS2490S+T&R

Overview

DS2490S+T&R from Maxim Integrated is a USB-to-1-Wire bridge IC that enables full-speed 12Mbps USB host communication with 1-Wire networks, supports regular/overdrive/flexible 1-Wire speeds, provides active 5V strong pullup for EEPROMs/sensors/iButton® devices, and features crystal-based timing precision (12MHz XO) for noise-immune waveform generation on long bus lines up to 300m.

For engineers reviewing the DS2490S+T&R datasheet, DS2490S+T&R pinout, DS2490S+T&R application, or DS2490S+T&R equivalent, this device serves as a dedicated protocol bridge-requiring no host-side 1-Wire timing control, supporting remote wake-up from 1-Wire events, and enabling robust multi-drop sensor or security token interfacing via standard USB infrastructure.

Technical Context

The DS2490S+T&R integrates a USB 1.1-compliant transceiver, USB device controller, and dedicated 1-Wire interface controller with active edge shaping and slew-rate-controlled pulldown. Its 12MHz crystal oscillator ensures precise 1-Wire timing across all speed modes-regular (65µs slot), overdrive (10.4µs slot), and flexible (configurable tLOW1/tDSO)-with programmable parameters stored in internal state registers.

It implements four USB endpoints: EP0 (control pipe for vendor commands), EP1 (interrupt pipe for status/attach detection, 1ms or 10ms polling), EP2 (bulk OUT for 1-Wire command/data), and EP3 (bulk IN for 1-Wire response data). Remote wake-up is supported but disabled at power-on default and requires explicit enablement via USB SET_FEATURE.

Key Specifications

Pinout & Package

DS2490S+T&R is housed in a 24-pin SOIC (300-mil) package with exposed pad not connected internally. Pin functions are validated per Maxim 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 and MAX31826, the DS2490S+T&R provides full programmability of 1-Wire timing, slew rate, and pullup behavior-making it the sole option for custom 1-Wire network topologies, long-line deployments, or mixed-device systems requiring vendor-command-level control.

Availability

DS2490S+T&R is available at Aetrix Electronics and suitable for industrial sensor hubs, secure access token readers, USB-based asset tracker dongles, and legacy system 1-Wire adapters requiring stable component supply and RoHS-compliant tape-and-reel packaging.

Supply support for DS2490S+T&R 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) is a semiconductor company specializing in analog, mixed-signal, and high-reliability interface solutions for industrial, computing, and security applications.

The DS2490 belongs to Maxim's 1-Wire interface product line, designed specifically to offload 1-Wire protocol timing and physical layer control from host processors-enabling robust, standards-compliant connectivity to Dallas Semiconductor-compatible devices.

FAQ

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

The DS2490S+T&R serves as a dedicated USB-to-1-Wire bridge IC that translates USB vendor-specific commands into precisely timed 1-Wire waveforms. It handles all physical-layer responsibilities-including reset generation, bit-level timing, active 5V pullup, and slew-controlled edges-relieving the host processor from real-time 1-Wire timing constraints. This makes DS2490S+T&R essential for deterministic, noise-immune communication with sensors, EEPROMs, and iButton® devices over extended 1-Wire networks.

Does the DS2490S+T&R support remote wake-up from USB suspend mode?

Yes, the DS2490S+T&R supports USB remote wake-up, but it is disabled by default at power-on. When explicitly enabled via USB SET_FEATURE command, the DS2490S+T&R asserts resume signaling upon detecting a 1-Wire device attachment event-allowing a suspended host system to wake and process the new device. The SUSO pin reflects USB suspend state and requires an external pullup resistor for proper operation.

What crystal frequency is required for the DS2490S+T&R, and why is it critical?

The DS2490S+T&R requires a 12.0MHz fundamental-mode parallel-resonant crystal connected between XI and XO pins. This crystal establishes the timing reference for all 1-Wire waveforms-including reset pulses, time slots, and strong pullup durations-ensuring ±0.5% accuracy across temperature. Using an RC oscillator would introduce unacceptable timing drift, risking failure in overdrive mode or with strict 1-Wire slave devices like DS1961S crypto iButton®.

Can the DS2490S+T&R drive long 1-Wire networks, and how is this achieved?

Yes, the DS2490S+T&R is engineered for long 1-Wire networks up to 300m. It achieves this through slew-rate-controlled pulldown (configurable to ~1V/µs), active rising-edge pullup to reduce rise time, and flexible-speed timing parameters (tLOW1, tDSO) that adapt to bus capacitance. These features minimize ringing, improve noise margin, and maintain signal integrity-verified in Maxim's application notes for multi-drop industrial installations using twisted-pair cabling.

What are the power supply requirements for the DS2490S+T&R, and how are they partitioned?

The DS2490S+T&R requires three distinct supplies: VB = 3.3V ±10% for USB core logic (regulated from VBUS), VD = 5.0V ±10% for digital and 1-Wire I/O, and VD2 which must be externally tied to VD. This separation isolates noise-sensitive USB signaling from 1-Wire drive circuitry. Decoupling capacitors (0.1µF ceramic + 10µF tantalum) are mandatory at each supply pin per Maxim's layout guidelines to ensure stable operation under dynamic 1-Wire load conditions.