Analog Devices Inc./Maxim Integrated DS2505P+T&R

Overview

DS2505P+T&R from Maxim Integrated (now Analog Devices) is a 16 kbit add-only EPROM IC operating on the 1-Wire® bus, featuring a factory-lasered 64-bit ROM (8-bit family code 0BH + 48-bit serial number + 8-bit CRC), 64 pages of 256-bit memory, single-pin parasitic-power operation, and page-level write protection. It enables traceable asset tagging and calibration storage in industrial sensors and medical devices.

For engineers reviewing the DS2505P+T&R datasheet, DS2505P+T&R pinout, DS2505P+T&R application, or DS2505P+T&R equivalent, key selection criteria include 1-Wire protocol compliance, 2.8–6.0 V read voltage range, 11.5–12.0 V programming requirement, TSOC package dimensions (3.7 × 4.0 × 1.5 mm), and guaranteed-unique 48-bit serial identity for secure device authentication.

Technical Context

The DS2505P+T&R implements a hierarchical 1-Wire protocol stack requiring ROM Function Commands (Read/Match/Search/Skip ROM) before enabling Memory Function Commands (Read/Write Memory, Read/Write Status, Extended Read). Its internal architecture separates 64-bit lasered ROM, 16384-bit EPROM data memory, and 704-bit EPROM status memory - with dedicated scratchpad buffering and CRC validation for each transaction.

Power is derived entirely from the 1-Wire line via parasitic capacitance during high periods; programming requires externally pulsed 12 V at 10 mA for 480 µs per byte. Page redirection is implemented via 64 one's-complement address bytes in status memory (100H–13FH), enabling software-managed data patching without physical erasure.

Key Specifications

Pinout & Package

DS2505P+T&R is housed in a 6-pin TSOC surface-mount package (3.7 × 4.0 × 1.5 mm), RoHS-compliant and lead-free. Pin 1 is DATA, Pin 2 is GND; Pins 3–6 are no-connect (NC).

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS2430A+ and DS28EC20, the DS2505P+T&R uniquely combines guaranteed-unique factory ROM, irreversible add-only memory, and software-managed page redirection - making it irreplaceable for applications requiring immutable, auditable data histories without cryptographic overhead.

Availability

DS2505P+T&R is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device asset tagging, equipment maintenance logging, and secure access credentialing requiring stable component supply and long-term lifecycle support.

Supply support for DS2505P+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 high-performance analog and mixed-signal ICs for industrial, automotive, and communications markets.

The DS2505P+T&R belongs to Maxim's 1-Wire memory product line, engineered specifically for low-pin-count, parasitic-powered identification and traceability in space-constrained, cost-sensitive embedded systems.

FAQ

What is the function of the DS2505P+T&R in a 1-Wire system?

The DS2505P+T&R serves as a tamper-evident, add-only memory node on a 1-Wire bus. It provides factory-guaranteed unique identification via its 64-bit lasered ROM and stores up to 16 kbit of user data in 64 programmable pages. Its role is to enable traceability and calibration retention in systems where minimal wiring, low cost, and data immutability are critical - such as industrial sensors and medical devices. The DS2505P+T&R does not require external power or clock signals, drawing all operating energy parasitically from the 1-Wire line.

Can the DS2505P+T&R be reprogrammed multiple times?

Yes, the DS2505P+T&R supports multiple programming operations, but only in "add-only" mode: individual bits can transition from logical 1 to 0, never from 0 to 1. This means data can be appended or pages redirected, but existing 0-bits cannot be restored to 1. Each page may be written once, then permanently write-protected via status memory. To update data, software uses page address redirection (stored in status memory addresses 100H–13FH) to point readers to newly programmed replacement pages - preserving full audit history. The DS2505P+T&R thus enables versioned, non-erasable data storage.

What voltage levels are required to operate and program the DS2505P+T&R?

The DS2505P+T&R reads data across 2.8 V to 6.0 V at temperatures from –40°C to +85°C, powered entirely parasitically from the 1-Wire line. Programming requires externally generated 11.5 V to 12.0 V pulses applied to the same DATA line for 480 µs per byte, with current capability of at least 10 mA. These high-voltage pulses must be precisely timed and isolated from the host microcontroller's I/O pin using a dedicated HV driver circuit - the DS2505P+T&R contains internal detection logic to enable programming mode only when 12 V is present.

How does the DS2505P+T&R ensure data integrity during read and write operations?

The DS2505P+T&R enforces data integrity through mandatory 16-bit CRC validation at three levels: (1) after every ROM function command (e.g., Match ROM), (2) after each memory command's address and data payload (e.g., Write Memory), and (3) at the end of every 32-byte page during Extended Read Memory. CRCs are computed using polynomial X¹⁶ + X¹⁵ + X² + 1 and verified by both the DS2505P+T&R and the bus master. If mismatch occurs, the bus master must issue a reset pulse and restart the sequence - preventing undetected corruption in calibration records or asset logs stored in the DS2505P+T&R.

Is the DS2505P+T&R pin-compatible with other 1-Wire memory devices like the DS2430A+?

No, the DS2505P+T&R is not pin-compatible with the DS2430A+. While both use 6-pin TSOC packages, the DS2505P+T&R assigns Pin 1 to DATA and Pin 2 to GND, with Pins 3–6 as NC. The DS2430A+ uses Pin 1 as V_DD, Pin 2 as GND, and Pin 3 as I/O - requiring different PCB layout and power architecture. Furthermore, the DS2505P+T&R relies solely on parasitic power and lacks a V_DD pin, whereas the DS2430A+ supports both parasitic and external power modes. Interchangeability would require redesign of the 1-Wire interface circuitry and firmware protocol handling.