Analog Devices Inc./Maxim Integrated DS24B33Q+U

Overview

DS24B33Q+U from Analog Devices is a 4096-bit, 1-Wire® EEPROM organized as 16 pages of 256 bits each, featuring a 32-byte scratchpad for verified write operations, unique 64-bit factory-programmed registration number, and open-drain IO interface operating from +2.8V to +5.25V at -40°C to +85°C. It serves as a secure, low-pin-count nonvolatile memory for calibration storage and board identification in parasitically powered sensor nodes.

For engineers reviewing the DS24B33Q+U datasheet, DS24B33Q+U pinout, DS24B33Q+U application, or DS24B33Q+U equivalent, this page delivers verified electrical specs (e.g., 15.4kbps/125kbps 1-Wire speeds, ±8kV contact ESD), package-specific terminal mapping (TDFN-EP, 6-pin), endurance (50k cycles @ +85°C), data retention (40 years @ +85°C), and functional compatibility with DS2433.

Technical Context

The DS24B33Q+U implements a parasitic-power 1-Wire slave architecture with strict timing compliance for standard (65µs slot) and overdrive (8µs slot) modes. Its IO pin functions as an open-drain bidirectional bus interface requiring external pullup, with hysteresis (0.2–1.7V) and switching thresholds (VTL = 0.5V, VTH = VPUP − 1.0V) optimized for noise immunity on shared buses.

Memory access follows a two-phase protocol: data is first written to the volatile 32-byte scratchpad and verified via CRC-16 before copying to EEPROM. The device uses three address registers (TA1, TA2, E/S) and supports ROM function commands (Match ROM, Search ROM) and memory commands (Write Scratchpad [0Fh], Copy Scratchpad [55h], Read Memory [F0h]) with LSB-first bit ordering.

Key Specifications

Pinout & Package

DS24B33Q+U is housed in a 6-pin TDFN-EP (3mm × 3mm) package with exposed pad soldered to ground plane for thermal and electrical stability. Pin 1 is N.C., Pin 2 is IO (1-Wire bus interface), Pin 3 is GND, Pins 4–6 are N.C., and the EP pad must be connected to system ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS24B33Q+U, DS2433+T&R offers lower-cost packaging but reduced ESD robustness and no thermal pad, while DS24B33S+T&R provides identical electrical behavior in SOIC format-making DS24B33Q+U the optimal choice for space-constrained, thermally demanding, or high-reliability 1-Wire node designs.

Availability

DS24B33Q+U is available at Aetrix Electronics and suitable for calibration data storage, board identification, and product revision logging requiring stable component supply across automotive Tier-1, industrial IoT, and medical device production programs.

Supply support for DS24B33Q+U 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 DS24B33Q+U belongs to Analog Devices' 1-Wire EEPROM product line, engineered for secure, low-pin-count, parasitically powered nonvolatile memory in distributed sensor and identification systems.

FAQ

What is the function of the exposed pad (EP) on the DS24B33Q+U?

The exposed pad on the DS24B33Q+U is a thermal and electrical ground connection that must be soldered evenly to the PCB's ground plane. It improves thermal dissipation during EEPROM programming (which draws 2mA) and enhances signal integrity on the 1-Wire bus by reducing noise coupling. Leaving the EP unconnected violates the device's operational specification and may cause intermittent communication or premature failure.

Is DS24B33Q+U pin-compatible with DS2433?

DS24B33Q+U is not pin-compatible with DS2433 due to its 6-pin TDFN-EP package versus DS2433's 2-pin TO-92 or 8-pin SOIC variants. While both share identical 1-Wire command sets and memory architecture, the DS24B33Q+U requires a custom footprint with EP grounding. Software and protocol-level compatibility is maintained, but PCB layout changes are mandatory for substitution.

How does the scratchpad verification process work in DS24B33Q+U?

In DS24B33Q+U, data is first written to the 32-byte scratchpad using the Write Scratchpad [0Fh] command. The device calculates a CRC-16 of the command, target address, and data bytes. The host can then read back the scratchpad contents-including TA1, TA2, and E/S register-and verify integrity before issuing Copy Scratchpad [55h]. If the PF (partial byte) flag is set or AA (authorization accepted) remains unset, the write failed and must be retried.

What is the maximum number of DS24B33Q+U devices supported on a single 1-Wire bus?

The DS24B33Q+U supports multidrop operation with no hard upper limit on device count-only constrained by bus capacitance, pullup strength, and timing margins. In practice, up to 100 devices have been validated on properly terminated 1-Wire buses using active pullups like the DS2482-100. Each DS24B33Q+U is uniquely addressed via its factory-programmed 64-bit ROM ID, enabling individual access without address conflicts.

Does DS24B33Q+U require an external power supply (VCC) or operate parasitically?

DS24B33Q+U operates exclusively in parasitic power mode-it derives all operating energy from the 1-Wire bus via the IO pin and requires no separate VCC connection. During EEPROM programming, the IO line must maintain ≥2.8V under load; therefore, the external pullup must be sized to sustain voltage during the 5ms tPROG interval, especially in multi-device networks where bus capacitance increases current demand.