Texas Instruments BQ24401DR

Overview

BQ24401DR from Texas Instruments is a programmable monolithic NiCd/NiMH fast-charge management IC with ΔT/Δt, maximum temperature, and maximum time termination. It features integrated high-speed comparator, push-pull MOD output for current control, open-drain LED status indicator, and RC-programmable timing. Used in multi-cell nickel-based battery chargers requiring safe, adaptive charge qualification and top-off.

For engineers reviewing the BQ24401DR datasheet, BQ24401DR pinout, BQ24401DR application, or BQ24401DR equivalent, key selection considerations include its 8-pin SOIC package, VCC range of 4–6 V, sleep current of 5 µA, programmable MTO timing via RC network, and support for trickle-charge revival of deeply discharged cells.

Technical Context

The BQ24401DR implements a hysteretic current-control loop using SNS input to regulate fast-charge current via MOD output, with user-defined RSNS setting IMAX = 0.05 / RSNS. It samples TS every 8 seconds during fast charge to compute ΔT/Δt using internal ADC and voltage thresholds referenced to VCC.

Charge state progression follows a deterministic finite-state machine: initiation → charge qualification (trickle if VBAT < 950 mV) → fast charge (current-regulated) → optional top-off (IMAX/16 pulses at 1 Hz) → trickle maintenance. Sleep mode activates when VBAT > VCC−1 V, reducing ICCS to 5 µA.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (Narrow) - surface-mount, industry-standard footprint compatible with automated assembly and thermal relief design.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NiCd/NiMH charge management applications.

Compared with BQ24401DR, BQ24400DR lacks top-off and programmable hold-off-reducing NiMH capacity utilization-while MAX713CPA+ offers wider VCC range and discrete control at the cost of increased BOM count and design complexity.

Availability

BQ24401DR is available at Aetrix Electronics and suitable for portable power tools, medical handheld devices, emergency lighting systems, and two-way radio chargers requiring stable component supply and long-term lifecycle support.

Supply support for BQ24401DR 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

Texas Instruments is a global semiconductor company specializing in analog and embedded processing technologies, with leadership in power management and battery solutions.

The bq244xx family was designed specifically for autonomous, high-safety nickel-based battery charging in consumer, industrial, and medical equipment-emphasizing analog precision, thermal robustness, and minimal external component count.

FAQ

What termination methods does the BQ24401DR use for NiCd/NiMH fast charging?

The BQ24401DR uses three independent fast-charge termination methods: rate of temperature rise (ΔT/Δt) measured every 8 seconds, maximum cell voltage (VMCV = 2.00 V ±2.5%), and programmable maximum charge time (MTO). All three are active simultaneously, and termination occurs upon first violation. This triple-criteria approach ensures safety across varying battery ages, temperatures, and chemistries without software intervention.

How does the BQ24401DR handle deeply discharged or shorted NiMH batteries?

The BQ24401DR initiates pre-charge qualification when VBAT falls below 950 mV. It then applies 1 Hz pulse-trickle charge via the MOD output to safely condition the cell. During this phase, the LED flashes at 1 Hz, and charging remains suspended until VBAT exceeds 950 mV and TS remains within VLTF–VHTF. This prevents damage to defective or over-discharged packs before fast-charge begins.

Can the BQ24401DR be used with both NiCd and NiMH battery chemistries?

Yes, the BQ24401DR is explicitly designed for both NiCd and NiMH chemistries. Its termination algorithms-including ΔT/Δt sensitivity, VMCV = 2.00 V/cell, and optional top-off-are optimized for nickel-based electrochemistry. The datasheet confirms identical functional behavior across both chemistries, with no configuration changes required when switching between them.

What is the role of the RC pin on the BQ24401DR, and how is it configured?

The RC pin on the BQ24401DR programs multiple timing functions: maximum charge time (MTO), hold-off period (MTO/32), top-off enable/disable, and trickle pulse-width. It uses an external resistor (RMTO, 2–250 kΩ) from RC to VSS and capacitor (CMTO, 0.001–1 µF) from RC to VCC. The resulting RC network generates a sawtooth waveform during active timing, allowing real-time state diagnosis without additional test points.

Does the BQ24401DR support battery removal and reinsertion detection?

Yes, the BQ24401DR detects battery removal and insertion autonomously. When the battery is removed, VBAT drops below VSLP (VCC−1 V), exiting sleep mode and triggering reinitialization. Upon reinsertion, the IC performs full charge qualification-including voltage and temperature checks-before resuming charging. This behavior is inherent to the analog state machine and requires no external circuitry or host processor interaction.