Analog Devices Inc./Maxim Integrated DS2438Z+

Overview

DS2438Z+ from Maxim Integrated is a smart battery monitor IC with integrated 1-Wire® interface, on-chip temperature sensor (−55°C to +125°C, 0.03125°C resolution), 10-bit battery voltage ADC (0–10 V, 10 mV LSB), current sensing via external shunt (36.41 Hz sampling), and 40-byte nonvolatile EEPROM for battery-specific data storage. It serves as the core fuel-gauge and health-monitoring element in rechargeable battery packs.

For engineers reviewing the DS2438Z+ datasheet, DS2438Z+ pinout, DS2438Z+ application, or DS2438Z+ equivalent, key selection concerns include 1-Wire bus compatibility, parasitic power operation, ICA/CCA/DCA accumulator behavior, temperature-to-digital conversion format, and VAD/VDD voltage source selection for ADC measurements.

Technical Context

The DS2438Z+ implements a parasitically powered 1-Wire slave device with a 64-bit lasered ROM (family code 0x26) enabling multi-drop bus operation. Its internal architecture integrates a two-stage A/D subsystem: one dedicated to battery voltage (10-bit, 10 mV LSB), another to current-derived voltage across VSENS± (12-bit, 0.2441 mV LSB), plus an on-die bandgap temperature sensor digitized to 13-bit two's complement format.

It features three synchronized accumulators - Integrated Current Accumulator (ICA, 8-bit volatile, 0.4882 mV·hr LSB), Charging Current Accumulator (CCA), and Discharge Current Accumulator (DCA) - all configurable via Status/Configuration Register bits (IAD, CA, EE) and backed by shadow-to-EEPROM capability. The elapsed time meter provides 4-byte binary seconds counter with 1-second resolution and disconnect/end-of-charge timestamp registers.

Key Specifications

Pinout & Package

DS2438Z+ is housed in an 8-pin SOIC (150-mil) package with lead-free finish. Pin 6 and Pin 7 are no-connect terminals; Pin 5 (VDD) accepts 2.4 V to 10.0 V supply; parasitic power operation is supported via DQ pin when VDD is unconnected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar smart battery monitor applications.

Compared with DS2438Z+, BQ2019DBTR requires additional signal conditioning and lacks integrated temperature sensing, while MAX17043G+T delivers superior SoC accuracy but forfeits 1-Wire simplicity and user EEPROM flexibility-making DS2438Z+ optimal for cost-sensitive, multi-drop, chemistry-agnostic battery packs.

Availability

DS2438Z+ is available at Aetrix Electronics and suitable for portable computing, handheld instrumentation, and consumer electronics battery-pack designs requiring stable component supply, long-lifecycle support, and 1-Wire bus compatibility.

Supply support for DS2438Z+ 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 U.S.-based semiconductor company specializing in precision analog, mixed-signal, and power-management ICs for industrial, computing, and consumer applications.

The DS2438Z+ belongs to Maxim's 1-Wire Smart Battery Monitor product line, designed specifically to embed intelligence into battery packs-enabling chemistry-independent fuel gauging, health diagnostics, and secure identification without adding system-level complexity.

FAQ

What is the operating voltage range for DS2438Z+?

The DS2438Z+ operates from 2.4 V to 10.0 V on the VDD pin. It also supports parasitic power mode where VDD is unconnected and power is drawn from the DQ line during high states-enabling operation even when the battery is fully discharged. In parasitic mode, timing and pull-up requirements per the 1-Wire specification must be strictly observed to ensure reliable power harvesting and communication.

Does DS2438Z+ require an external thermistor?

No, DS2438Z+ does not require an external thermistor. It incorporates an on-die temperature sensor with calibrated output over −55°C to +125°C and 0.03125°C resolution in 13-bit two's complement format. This eliminates board space, cost, and calibration effort associated with discrete thermistors-making DS2438Z+ ideal for sealed battery packs where external sensors are impractical.

How does DS2438Z+ handle current measurement accuracy and offset calibration?

DS2438Z+ performs continuous current measurement at 36.41 Hz across VSENS± and stores raw values in a two's complement Current Register (0.2441 mV LSB). It includes a nonvolatile Offset Register to cancel ADC offset errors: users write the two's complement of a zero-current reading to this register while the IAD bit is disabled. This calibration is performed at factory and recommended again during battery pack assembly to maintain <±2 LSB accuracy over temperature and time.

Can DS2438Z+ measure both battery voltage and an auxiliary voltage simultaneously?

No, DS2438Z+ cannot measure both voltages simultaneously. Its single 10-bit ADC can be configured-via the Status/Configuration Register-to sample either VDD (battery voltage) or VAD (auxiliary input), but not both at once. A "Convert V" command triggers one measurement, and the result populates the same 2-byte Voltage Register. To monitor two sources, external multiplexing or sequential sampling with software coordination is required.

What is the function of the Disconnect Timestamp in DS2438Z+?

When DS2438Z+ detects DQ held low for approximately 2 seconds-indicating physical removal from the host-it automatically writes the current Elapsed Time Meter value to the Disconnect Timestamp register and enters low-power sleep mode (except in DS2438AZ+ variant). Upon reconnection, the host reads this timestamp to compute storage duration and apply self-discharge correction to the ICA-derived remaining capacity-ensuring accurate SoC reporting after extended shelf life.