Analog Devices Inc./Maxim Integrated DS1481S+T&R

Overview

DS1481S+T&R from Maxim Integrated is a dedicated 1-Wire® bus master timing generator for parallel-port-based host interfaces, supporting standard and overdrive-speed communication (tSIO = 8 μs / 2 μs), reset generation (≥480 μs low pulse), and cascaded multi-device configurations. It operates from 2.7 V to 5.5 V and is packaged in a 14-pin SO (150 mil) for short-reach 1-Wire networks (<3 inches), commonly used with legacy PC parallel ports and microcontroller coexistence designs.

For engineers reviewing the DS1481S+T&R datasheet, DS1481S+T&R pinout, DS1481S+T&R application, or DS1481S+T&R equivalent, key selection considerations include its dual busy-signal arbitration (O1/BSY1 & O2/BSY2), transparent/EPP/ECP mode toggle sequence, ENI-triggered time-slot execution, and I/O line state sampling at tSIO - all critical for spooler-safe 1-Wire host integration.

Technical Context

The DS1481S+T&R implements a hardware-timed 1-Wire bus master with synchronous control via D/CLK and RES inputs, where logic states define read/write/reset operations before ENI activation. It uses open-drain I/O with 40 mA drive capability and internal 50 kΩ pullups on I1, I2, ENI, D/CLK, RES, and ENO.

Its dual-mode operation includes standard-speed (tBLB = 60 μs, tBLR = 960 μs) and overdrive-speed (tBLB = 6 μs, tBLR = 96 μs) timing, with automatic OD-bit toggling via four consecutive overdrive commands. The device detects last-in-stack position by monitoring absence of upstream busy signals, disabling I1/I2 propagation during ENI assertion.

Key Specifications

Pinout & Package

DS1481S+T&R is housed in a 14-pin SOIC package (150 mil width), with exposed pad omitted and NC pins unused. Pin functions are electrically validated per Maxim's official DS1481 datasheet Rev. 0, pages 2–3 and 8.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 1-Wire bus master applications.

Compared with DS1481S+T&R, DS2480B+ and DS2490 eliminate parallel port dependency and extend 1-Wire reach but sacrifice spooler-safe busy signaling and cascaded topology support - making them unsuitable for legacy LPT-based systems requiring printer coexistence.

Availability

DS1481S+T&R is available at Aetrix Electronics and suitable for legacy PC peripheral integration, microcontroller-based sensor bridges, industrial data loggers, and printer-embedded environmental monitors requiring stable component supply and long-term obsolescence management.

Supply support for DS1481S+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 power management ICs for industrial, communications, and computing applications.

The DS1481S+T&R belongs to Maxim's 1-Wire interface product line, designed specifically to simplify host-side 1-Wire protocol implementation in parallel-port and microcontroller systems without firmware timing constraints.

FAQ

What is the primary function of the DS1481S+T&R in a 1-Wire system?

The DS1481S+T&R serves as a hardware-based 1-Wire bus master that generates precise reset pulses and time-slot waveforms for Dallas Semiconductor 1-Wire devices. It interfaces directly with parallel ports or microcontrollers via D/CLK and RES control lines, offloading timing-critical tasks from the host processor. Unlike software-driven solutions, DS1481S+T&R guarantees compliance with 1-Wire timing specifications including tBLR ≥960 μs for reset and tSIO = 8 μs for standard-speed communication - making it essential for reliable legacy-system integration.

Does the DS1481S+T&R support overdrive mode, and how is it enabled?

Yes, the DS1481S+T&R supports overdrive mode for accelerated 1-Wire communication (tSIO = 2 μs). It is enabled by issuing four consecutive overdrive toggle commands - achieved by setting D/CLK and RES low and pulsing ENI low four times. After the fourth pulse, the DS1481S+T&R toggles its internal OD bit and enters overdrive mode. No external configuration or register writes are required; the DS1481S+T&R handles all timing adjustments autonomously, maintaining full backward compatibility with standard-speed devices.

How does the DS1481S+T&R handle coexistence with parallel-port printers?

The DS1481S+T&R manages printer coexistence using dual input/output pins: I1/I2 accept printer BUSY and SELECT OUT signals, while O1/BSY1 and O2/BSY2 drive corresponding status lines back to the host. When ENI is inactive, O1/BSY1 and O2/BSY2 propagate I1/I2 states - allowing uninterrupted printer operation. During 1-Wire I/O, the DS1481S+T&R asserts busy signals to pause spooling, then restores I1/I2 states post-execution. Its last-part detection logic further prevents bus conflicts when multiple DS1481S+T&R units are cascaded behind a printer.

What package type and pin count does the DS1481S+T&R use?

The DS1481S+T&R is supplied in a 14-pin small-outline integrated circuit (SOIC) package with 150-mil body width. This surface-mount package includes two no-connect (NC) pins (pins 7, 9, and 10 - three total per datasheet, though only pins 7 and 9 are marked NC in pinout diagrams), GND (pin 8), VCC (pin 1), and dedicated 1-Wire I/O (pin 14). The layout matches JEDEC MS-012AC standards, enabling drop-in replacement in existing parallel-port adapter PCBs designed for the DS1481 family.

Is the DS1481S+T&R recommended for new designs, and why?

No, the DS1481S+T&R is explicitly marked "Not Recommended for New Design" in Maxim's official documentation due to its dependence on legacy parallel port infrastructure and lack of modern interface support (e.g., USB, I²C, SPI). While fully functional and supported for existing systems, new designs should consider alternatives like the DS2480B+ (USB-to-1-Wire) or DS2490 for improved noise immunity and longer bus reach. DS1481S+T&R remains viable for repair, maintenance, and life-extension programs targeting installed base equipment with parallel ports.