Analog Devices Inc./Maxim Integrated DS2484Q+T

Overview

The DS2484Q+T from Analog Devices is a single-channel I²C-to-1-Wire® bridge IC that functions as a 1-Wire master, enabling standard (100kHz) and fast (400kHz) I²C hosts to control 1-Wire slave devices such as DS18B20 temperature sensors and DS2431 EEPROMs. It supports both standard and overdrive 1-Wire speeds, features user-adjustable timing (tRSTL, tMSP, tW0L, tREC0), dual-voltage operation (I²C side: 1.8V/3.3V/5.0V; 1-Wire side: 1.8V–5.0V), and integrated strong pullup for parasitic-power delivery.

For engineers reviewing the DS2484Q+T datasheet, DS2484Q+T pinout, DS2484Q+T application, or DS2484Q+T equivalent, key selection considerations include its adjustable 1-Wire timing registers, sleep mode via SLPZ pin (4µA typical ICC), ±8kV HBM ESD protection on IO, and support for industrial sensor networks requiring reliable bus arbitration and power management across mixed-voltage systems.

Technical Context

The DS2484Q+T implements a self-timed 1-Wire controller with dedicated input/output logic that executes time-critical waveforms-including reset/presence-detect, read-byte, write-byte, and triplet-without host CPU intervention. Its internal timing engine derives all 1-Wire timing parameters (tRSTL, tMSP, tW0L, tREC0) from a single oscillator, ensuring consistency across standard and overdrive modes.

It integrates three distinct pullup mechanisms: passive (RWPU = 375–1375Ω), active (RAPU = 40–100Ω, fixed-duration), and strong (same transistor, extended conduction). The Device Configuration register controls APU, PDN, SPU, and 1WS bits independently, while the Status register provides real-time feedback (PPD, SD, 1WB, SBR) for robust error handling in noisy environments.

Key Specifications

Pinout & Package

DS2484Q+T is packaged in an 8-pin TDFN (2mm × 3mm, exposed pad) with lead-free RoHS-compliant finish. Pin 1 is marked by a dot; the exposed pad (EP) must be soldered to PCB ground for thermal and electrical stability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C-to-1-Wire bridge applications.

Compared with DS2482-100+T, DS2484Q+T delivers overdrive speed, user-adjustable timing, and superior ESD robustness - critical for high-reliability medical and industrial deployments. Against MAX31826ATK+, DS2484Q+T offers broader 1-Wire peripheral compatibility and deterministic timing control, making it the preferred choice for systems integrating diverse 1-Wire devices beyond temperature sensing.

Availability

DS2484Q+T is available at Aetrix Electronics and suitable for industrial sensor networks, medical instrumentation, printer peripheral management, and cell phone accessory authentication requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for DS2484Q+T 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

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets with precision components and system-level solutions.

The DS2484Q+T belongs to Analog Devices' 1-Wire interface product line, engineered specifically to simplify integration of legacy and modern 1-Wire sensors and security devices into I²C-based embedded systems while maintaining timing fidelity and power efficiency.

FAQ

What is the primary function of the DS2484Q+T in an embedded system?

The DS2484Q+T serves as an I²C-to-1-Wire bridge IC, acting as a hardware-managed 1-Wire master that relieves the host microcontroller from generating time-critical 1-Wire waveforms. It handles reset/presence detection, read/write byte, single-bit, and triplet commands autonomously, reporting status (PPD, SD, 1WB) via its Status register. This offloads timing-critical tasks from firmware, improving system determinism and reducing CPU overhead in applications like sensor networks and secure authentication.

How does the DS2484Q+T support dual-voltage operation between I²C and 1-Wire domains?

The DS2484Q+T separates I²C and 1-Wire voltage domains: the SLPZ pin supplies the I²C interface voltage (VCI2C), which can be 1.8V, 3.3V, or 5.0V, while the VCC pin powers the core logic and 1-Wire driver, supporting 1.71V–5.25V. The IO pin operates across 1.8V–5.0V independently of VCI2C, enabled by an integrated level translator. This eliminates external level-shifting components when connecting a 1.8V I²C MCU to a 5V 1-Wire EEPROM or temperature sensor - a key advantage of the DS2484Q+T over simpler bridges.

Can the DS2484Q+T drive parasitic-powered 1-Wire devices, and how is this implemented?

Yes, the DS2484Q+T supports parasitic-powered 1-Wire devices via its programmable strong pullup (SPU) feature. When activated, the same internal FET used for active pullup conducts continuously during specified 1-Wire commands (e.g., Write Byte), delivering up to ~100mA peak current to charge the parasite capacitor of devices like DS2431 EEPROMs or DS1920 temperature sensors. The RAPU parameter (40–100Ω) ensures sufficient voltage margin at the 1-Wire bus under load - a capability explicitly documented for the DS2484Q+T in its Electrical Characteristics table and functional description.

What timing parameters of the DS2484Q+T are user-adjustable, and how are they configured?

The DS2484Q+T provides four user-adjustable 1-Wire timing parameters: tRSTL (reset low time), tMSP (presence-detect sample time), tW0L (write-zero low time), and tREC0 (write-zero recovery time). These are stored in the Port Configuration register and configured using the "Adjust 1-Wire Port" command (0xD2). Each parameter has separate standard and overdrive values, encoded as 4-bit values per Table 7 in the datasheet. This adjustability allows system designers to optimize bus timing for cable length, capacitance, and slave device tolerances - a distinguishing feature of the DS2484Q+T versus fixed-timing alternatives.

How does the sleep mode of the DS2484Q+T reduce system power consumption?

The DS2484Q+T enters ultra-low-power sleep mode when the SLPZ pin is driven low, reducing supply current to 4µA (typical at VCC = 5.25V). In this state, the 1-Wire port goes high-impedance, isolating downstream devices, and internal clocks halt. Wake-up occurs on SLPZ rising edge with a guaranteed 2ms tSWUP delay before I²C communication resumes. This behavior is explicitly characterized in the DS2484Q+T datasheet's Electrical Characteristics table and enables significant energy savings in battery-powered applications such as handheld medical devices and portable printers - a verified design value of the DS2484Q+T.