Analog Devices Inc./Maxim Integrated DS2505+T&R

Overview

DS2505+T&R from Maxim Integrated (now Analog Devices) is a 16 kbit add-only EPROM memory IC with factory-lasered 64-bit ROM, operating via single-wire 1-Wire® interface. It provides traceable device identity (8-bit family code 0xBH, 48-bit serial number, 8-bit CRC), 64 pages of 256-bit memory, page-level write protection, and software-managed page redirection for data patching. Used in calibration storage, asset tracking, and maintenance logging where tamper-resistant, low-pin-count memory is required.

For engineers reviewing the DS2505+T&R datasheet, DS2505+T&R pinout, DS2505+T&R application, or DS2505+T&R equivalent, key selection considerations include its parasitic-power operation (2.8–6.0 V read, 11.5–12.0 V program), TO-92 tape-and-reel packaging, 16.3 kbps communication speed, and strict 1-Wire protocol compliance - especially ROM function command sequencing and EPROM status byte management.

Technical Context

The DS2505+T&R implements a hierarchical 1-Wire protocol requiring ROM Function Commands (Read/Match/Search/Skip ROM) before accessing memory functions. Its internal architecture separates 64-bit lasered ROM (for device singulation), 16384-bit EPROM data memory (64 × 256-bit pages), and 704-bit EPROM status memory (write-protect bits, page redirection bytes, and usage flags).

Power is derived entirely from the 1-Wire line during read operations using parasitic capacitance; programming requires externally pulsed 12 V at 10 mA. Data integrity relies on dual-layer CRC: 8-bit CRC over ROM contents and 16-bit CRC per memory transaction (scratchpad load, page read/write, status access), with all bit transfers LSB-first.

Key Specifications

Pinout & Package

DS2505+T&R is supplied in lead(Pb)-free TO-92 package (3.7 × 4.0 × 1.5 mm), tape-and-reel format. Pin configuration supports minimal PCB footprint and compatibility with standard automated assembly equipment.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS2505+T&R, DS2430A offers rewritable memory but lacks guaranteed uniqueness and page-level immutability, while DS28EC20 adds security features at the cost of complexity and incompatibility with simple add-only data logging workflows.

Availability

DS2505+T&R is available at Aetrix Electronics and suitable for calibration storage, asset tracking, product revision management, and access code vaulting requiring stable component supply, RoHS-compliant packaging, and long-term obsolescence mitigation.

Supply support for DS2505+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 (acquired by Analog Devices in 2021) designs precision analog, mixed-signal, and digital ICs for industrial, automotive, and computing applications.

The DS2505+T&R belongs to Maxim's 1-Wire memory product line, engineered specifically for secure, low-pin-count identification and immutable data logging in resource-constrained systems.

FAQ

What is the function of the NC pin on the DS2505+T&R?

The NC (No Connect) pin on the DS2505+T&R is internally unconnected and must remain floating or tied to ground per layout recommendations. It serves no electrical function and exists solely for mechanical symmetry in the TO-92 package. Incorrect routing or biasing of this pin has no effect on DS2505+T&R operation but may violate IPC assembly standards.

Can the DS2505+T&R be reprogrammed after initial write?

Yes - the DS2505+T&R supports multiple programming sessions, but only in "add-only" mode: existing bits can transition from 1 to 0, never from 0 to 1. New data is appended or replaces old data via page redirection in status memory. Once a page is write-protected, it cannot be altered, making DS2505+T&R ideal for auditable, versioned records.

What voltage is required to program the DS2505+T&R?

The DS2505+T&R requires a precisely timed 11.5 V to 12.0 V programming pulse (480 µs duration) on the DATA line, delivered while maintaining valid 1-Wire timing. This high-voltage pulse is generated externally by the bus master; the DS2505+T&R detects it internally to enable EPROM programming. Read operations use only 2.8–6.0 V.

How does the DS2505+T&R ensure data integrity during read operations?

The DS2505+T&R guarantees data integrity via built-in 16-bit CRC calculation per memory page during Extended Read Memory commands. Each page read concludes with a CRC computed over the actual stored data - not precomputed or stored - ensuring consistency even after field updates. The DS2505+T&R also validates all command/address sequences with CRC before execution.

Is the DS2505+T&R compatible with standard 1-Wire microcontroller libraries?

Yes - the DS2505+T&R fully complies with the Dallas Semiconductor 1-Wire protocol specification, including ROM function command sequencing (Read/Match/Search/Skip ROM) and memory function opcodes (F0H, AAH, A5H, 0FH). Standard 1-Wire drivers (e.g., Maxim's own OneWire library or open-source Arduino implementations) support DS2505+T&R without modification.