Analog Devices Inc./Maxim Integrated DS24B33+

Overview

DS24B33+ from Analog Devices is a 4096-bit, single-conductor 1-Wire® EEPROM organized as 16 pages of 256 bits each, featuring a 32-byte scratchpad for verified write operations, unique factory-programmed 64-bit registration number for multidrop bus addressing, and operation from +2.8V to +5.25V across –40°C to +85°C - used for board identification, calibration constant storage, and product revision tracking in industrial sensor nodes and embedded systems.

For engineers reviewing the DS24B33+ datasheet, DS24B33+ pinout, DS24B33+ application, or DS24B33+ equivalent, key selection considerations include 1-Wire parasitic power capability, 200k write/erase cycles at +25°C, ±8kV IEC 1000-4-2 ESD rating, 5ms EEPROM programming time, and TO-92 through-hole package compatibility with legacy DS2433 designs.

Technical Context

The DS24B33+ implements a fully compliant 1-Wire slave interface with ROM function command support (Read ROM, Match ROM, Skip ROM) followed by memory function commands (Write Scratchpad, Read Scratchpad, Copy Scratchpad, Read Memory). It derives all operating power parasitically from the IO line and uses internal CRC-16 generation (X¹⁶ + X¹⁵ + X² + 1) for data integrity verification during scratchpad writes.

Memory access follows a two-step protocol: data is first written to the volatile 32-byte scratchpad and verified before copying to nonvolatile EEPROM. Addressing uses 16-bit target registers (TA1/TA2), and transfer status is tracked via the E/S register containing partial byte flag (PF), authorization accepted (AA), and ending offset (E[4:0]).

Key Specifications

Pinout & Package

DS24B33+ is supplied in a lead(Pb)-free, RoHS-compliant TO-92 through-hole package (2-pin, 100-mil lead spacing), with GND and IO terminals only. The exposed pad variant (e.g., DS24B33Q+) is not applicable to this part number.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS2433+, the DS24B33+ offers double the write endurance and higher ESD robustness for harsher industrial use; compared with DS24B33AS+, it provides identical functionality in a through-hole form factor ideal for prototyping, repair, or legacy board upgrades.

Availability

DS24B33+ is available at Aetrix Electronics and suitable for industrial sensor calibration, PCB identification, and product revision management requiring stable component supply, long-term data retention, and proven 1-Wire interoperability.

Supply support for DS24B33+ 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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and connectivity applications.

The DS24B33+ belongs to Analog Devices' 1-Wire EEPROM product line, engineered specifically for reliable, low-pin-count nonvolatile storage in distributed sensor networks, asset tracking systems, and embedded identification solutions.

FAQ

What is the primary function of the DS24B33+ in a 1-Wire system?

The DS24B33+ serves as a 4096-bit nonvolatile EEPROM slave device on a 1-Wire bus, providing tamper-resistant, individually addressable storage for calibration data, board IDs, and configuration parameters. Its 64-bit factory-programmed ROM enables multidrop operation, and its parasitic power design eliminates the need for a separate VCC connection - making the DS24B33+ ideal for space- and cost-constrained embedded systems where the DS24B33+ integrates seamlessly with microcontroller 1-Wire drivers.

Does the DS24B33+ require an external power supply?

No, the DS24B33+ operates entirely from parasitic power harvested from the 1-Wire bus via its IO pin - eliminating the need for a dedicated VCC connection. This requires only an external pullup resistor (0.3–2.2 kΩ) on the IO line and compliance with timing specifications (e.g., tREC ≤ 10 µs before reset). During EEPROM programming, the DS24B33+ draws up to 2 mA, so the pullup network must maintain ≥2.8V on IO; the DS24B33+ thus supports ultra-low-pin-count designs where the DS24B33+ replaces traditional I²C/SPI EEPROMs.

How does the scratchpad mechanism in the DS24B33+ prevent data corruption?

The DS24B33+ uses a 32-byte volatile scratchpad as an intermediate buffer: data is first written to the scratchpad, then verified via Read Scratchpad before being copied to EEPROM using the Copy Scratchpad command. This two-step process ensures integrity - if power is lost or communication fails during write, only the scratchpad is affected, leaving EEPROM contents unchanged. The DS24B33+ also reports partial byte errors (PF flag) and authorization status (AA flag) to guide recovery, making the DS24B33+ highly resilient in noisy or intermittently powered environments.

Is the DS24B33+ pin-compatible with the DS2433+?

Yes, the DS24B33+ is software- and pin-compatible with the DS2433+, sharing identical 2-pin TO-92 packaging, same 64-bit ROM structure (including family code 0x23), identical memory map, and full command set compatibility. This allows direct replacement in existing DS2433+-based systems without hardware or firmware changes - though the DS24B33+ delivers improved specifications including 200k write cycles (vs. 100k), enhanced ±8kV/±15kV ESD protection, and tighter timing margins for robust operation.

What is the maximum recommended pullup resistance for the DS24B33+ IO line?

The DS24B33+ specifies a 1-Wire pullup resistance range of 0.3 kΩ to 2.2 kΩ under typical conditions - with lower values required for faster overdrive-speed operation or multi-device buses. At minimum VPUP (+2.8V), a steeper falling-edge slew rate (>15 V/µs) is recommended. For systems with more than one DS24B33+, active pullup (e.g., DS2482-x00) may be necessary to meet tREC and tW0L timing constraints. The DS24B33+ datasheet defines these limits precisely to ensure reliable reset detection and data sampling - critical for stable DS24B33+ deployment.