Analog Devices Inc./Maxim Integrated MAX6431EIUS+

Overview

MAX6431EIUS+ from Maxim Integrated is a dual-level, factory-trimmed battery monitor IC for single Li+ or multi-cell alkaline/NiMH/NiCd power supplies. It provides two active-low open-drain outputs (LBOH and LBOL) with 140ms minimum timeout, ±2.5% threshold accuracy, and 1µA typical supply current. It operates from 1.6V to 5.5V over –40°C to +85°C and is used to trigger low-power mode and system shutdown in portable medical devices and pagers.

For engineers reviewing the MAX6431EIUS+ datasheet, MAX6431EIUS+ pinout, MAX6431EIUS+ application, or MAX6431EIUS+ equivalent, key selection criteria include dual-threshold hysteresis behavior, guaranteed LBO logic state down to BATT = 1.0V, immunity to short voltage transients, and compatibility with SOT143-4 PCB layouts requiring minimal external components.

Technical Context

The MAX6431EIUS+ implements two independent comparators with internal reference and timing circuitry to monitor high- and low-battery thresholds simultaneously. Its factory-trimmed VHTH− (2.7V) and VLTH− (1.9V) thresholds define weak-battery and empty-battery states, while corresponding VHTH+ (2.835V) and VLTH+ (1.995V) set deassertion points with ~5% hysteresis.

It uses push-pull or open-drain output logic options; MAX6431EIUS+ specifically features open-drain LBOH/LBOL outputs referenced to GND, enabling interface with higher-voltage microcontrollers. The 140ms timeout ensures stable voltage recovery before deassertion, preventing chattering during battery recovery after load removal.

Key Specifications

Pinout & Package

MAX6431EIUS+ is housed in a lead-free 4-pin SOT143-4 package (3.0mm × 1.7mm × 1.3mm), optimized for space-constrained portable designs. Pin 1 is BATT, Pin 2 is LBOH, Pin 3 is GND, and Pin 4 is LBOL - all pins are surface-mount compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-threshold battery monitor applications.

Compared with MAX6430EIUS+, MAX6431EIUS+ offers safer interface flexibility via open-drain outputs, while compared with TLV809E27DBZR it delivers integrated dual-threshold decision logic-reducing BOM count, PCB area, and firmware complexity in portable battery-powered systems.

Availability

MAX6431EIUS+ is available at Aetrix Electronics and suitable for portable medical devices, pagers, legacy cellular handsets, and electronic toys requiring stable component supply with guaranteed long-term manufacturability and RoHS-compliant lead-free packaging.

Supply support for MAX6431EIUS+ 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 semiconductor company specializing in high-performance analog, mixed-signal, and power management solutions for industrial, automotive, and consumer applications.

The MAX6427–MAX6438 family was designed to deliver ultra-low-power, precision battery monitoring for space- and energy-constrained portable electronics - emphasizing factory-trimmed accuracy, minimal external components, and robust transient immunity.

FAQ

What is the exact factory-trimmed threshold voltage pair for MAX6431EIUS+?

The MAX6431EIUS+ features factory-trimmed thresholds of VHTH− = 2.7V (for LBOH assertion) and VLTH− = 1.9V (for LBOL assertion), with corresponding deassertion voltages VHTH+ = 2.835V and VLTH+ = 1.995V. These values are confirmed in Table 2 of the MAX6427–MAX6438 datasheet and correspond to the "EI" suffix in the part number.

Does MAX6431EIUS+ require external resistors to set its thresholds?

No, MAX6431EIUS+ does not require external resistors. As a factory-trimmed variant in the MAX6430–MAX6432 series, it integrates precision voltage references and comparator circuitry internally. All threshold voltages and hysteresis are laser-trimmed during production - eliminating external components and calibration effort.

Can MAX6431EIUS+ operate with a 1.0V battery supply?

Yes, MAX6431EIUS+ guarantees valid logic states on LBOH and LBOL outputs down to BATT = 1.0V, as explicitly stated in the datasheet's "Guaranteed Valid LBO Logic State to BATT = 1.0V" feature. This ensures reliable shutdown signaling even during deep discharge or low-temperature battery sag.

What is the purpose of the 140ms timeout period in MAX6431EIUS+?

The 140ms minimum timeout in MAX6431EIUS+ ensures that the battery voltage remains stably above the high threshold (VHTH+ or VLTH+) for at least that duration before deasserting LBOH or LBOL. This prevents chattering during transient recovery after load removal and guarantees stable enablement of power converters or microprocessors.

How does MAX6431EIUS+ differ from MAX6431EUS+?

MAX6431EIUS+ is the lead-free version (denoted by "+" suffix), while MAX6431EUS+ is the legacy leaded variant. Both share identical electrical specifications, pinout, and thermal performance. The "I" in MAX6431EIUS+ indicates the EI threshold option (2.7V/1.9V), and "US" denotes SOT143-4 packaging - confirming full functional and mechanical equivalence except for RoHS compliance.