Analog Devices Inc./Maxim Integrated MAX6431FJUS-T

Overview

MAX6431FJUS-T from Maxim Integrated is a dual-output, 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 and supports battery-good/weak/empty state indication in portable medical devices and cordless phones.

For engineers reviewing the MAX6431FJUS-T datasheet, MAX6431FJUS-T pinout, MAX6431FJUS-T application, or MAX6431FJUS-T equivalent, this device delivers precise dual-threshold monitoring without external components - critical for low-power, space-constrained battery management in consumer and industrial edge devices.

Technical Context

The MAX6431FJUS-T implements two independent comparators with internal hysteresis and fixed factory-trimmed thresholds: VHTH− (e.g., 2.8V) and VLTH− (e.g., 2.3V) for LBOH/LBOL assertion, plus corresponding VHTH+ (≈1.05×VHTH−) and VLTH+ (≈1.05×VLTH−) for deassertion. Its logic is referenced to BATT, not VDD, enabling direct battery-supplied operation.

It features guaranteed valid output states down to BATT = 1.0V, immunity to short voltage transients (<100µs), and stable 140–280ms timeout behavior across −40°C to +85°C. No external resistors or capacitors are required - all thresholds and timing are internally calibrated.

Key Specifications

Pinout & Package

SOT143-4 package: ultra-small surface-mount plastic package with 1.6mm × 2.9mm body, 0.95mm height, and 0.65mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6430FJUS-T, MAX6431FJUS-T offers higher trip points for Li+-optimized use cases; compared with TLV809E33DBZR, it delivers true dual-state battery intelligence with built-in hysteresis and timeout - eliminating design complexity and improving reliability in battery-critical applications.

Availability

MAX6431FJUS-T is available at Aetrix Electronics and suitable for portable medical devices, cordless phones, and electronic toys requiring stable component supply with long-term lifecycle assurance.

Supply support for MAX6431FJUS-T 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 precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX6427–MAX6438 family was designed specifically for ultra-low-power, component-minimized battery state monitoring - targeting applications where size, current budget, and reliability outweigh programmability needs.

FAQ

What is the function of the LBOH and LBOL outputs on the MAX6431FJUS-T?

The MAX6431FJUS-T features two independent active-low open-drain outputs: LBOH asserts when battery voltage falls below the factory-trimmed high-threshold (e.g., 2.8V), signaling "battery weak"; LBOL asserts at the lower factory-trimmed threshold (e.g., 2.3V), signaling "battery empty". Both include 140ms minimum timeout to prevent chatter during transient dips. Each output requires an external pull-up resistor to its target logic rail.

Does the MAX6431FJUS-T require external resistors to set its thresholds?

No. The MAX6431FJUS-T uses factory-trimmed internal thresholds - no external resistors, dividers, or capacitors are required. This distinguishes it from the adjustable-threshold MAX6436–MAX6438 series. Its VHTH−, VHTH+, VLTH−, and VLTH+ values are laser-trimmed during production and permanently fixed per orderable variant (e.g., FJUS-T corresponds to specific threshold codes per Maxim's ordering table).

Can the MAX6431FJUS-T operate with a 1.8V battery supply?

No. The MAX6431FJUS-T requires a minimum supply voltage of 1.6V to guarantee functional operation, but its factory-trimmed thresholds (e.g., 2.3V/2.8V) are intended for use with batteries whose nominal voltage exceeds those levels - such as single Li+ (3.0–4.2V) or 2–3-cell alkaline/NiMH (2.4–4.5V). At 1.8V, the device may power up but will assert both LBOH and LBOL continuously, as the supply is below usable threshold range.

What is the maximum sink current supported by the LBOH and LBOL pins of the MAX6431FJUS-T?

The MAX6431FJUS-T LBOH and LBOL outputs each support up to 3.2mA sink current while maintaining VOL ≤ 0.4V (at V_BATT ≥ 4.5V). At lower supply voltages (≥2.7V), they sustain 1.2mA with VOL ≤ 0.3V, and at ≥1.6V, 100µA with VOL ≤ 0.3V. These ratings ensure compatibility with standard logic inputs and LED drivers without additional buffering.

How does the 140ms timeout period improve system reliability in the MAX6431FJUS-T?

The 140ms minimum timeout in the MAX6431FJUS-T prevents premature re-enabling of system functions after brief voltage sags - such as those caused by motor startup or RF transmission. By holding LBOH/LBOL asserted until BATT remains above the deassertion threshold for ≥140ms, the MAX6431FJUS-T ensures the battery has truly recovered, avoiding repeated sleep/wake cycles that degrade firmware stability and user experience.