Texas Instruments BQ29401DCT3E6

Overview

BQ29401DCT3E6 from Texas Instruments is a BiCMOS secondary overvoltage protection IC for 2-, 3-, or 4-cell Li-ion battery packs. It provides precise cell voltage monitoring with ±25 mV accuracy at 4.45 V, programmable delay timing via external capacitor (0.22 µF typical), <2 µA supply current, and drives an external N-channel FET to blow a fuse during overvoltage events. It is used in notebook PCs and portable medical instrumentation as second-level safety protection.

For engineers reviewing the BQ29401DCT3E6 datasheet, BQ29401DCT3E6 pinout, BQ29401DCT3E6 application, or BQ29401DCT3E6 equivalent, key selection considerations include its fixed 4.45 V overvoltage threshold, 8-pin DCT (MSOP-8) package, CD pin-based delay programming, GND-referenced VC4 input, and compatibility with series-connected Li-ion cell stacks requiring fail-safe secondary cutoff.

Technical Context

The BQ29401DCT3E6 implements independent per-cell voltage comparison against a precision internal reference, triggering protection only when any single cell exceeds 4.45 V ±25 mV. Its internal current source (0.2 µA nominal) charges an external capacitor on the CD pin to generate a programmable delay before OUT activation.

Upon reaching 1.2 V at CD, the OUT pin transitions high to enable an external N-channel FET; it returns low only after all cells fall below (4.45 V – 300 mV hysteresis). The device supports 2–4 series configurations via configurable VC1–VC4 inputs and operates across –25°C to 85°C with supply voltage up to 25 V.

Key Specifications

Pinout & Package

The BQ29401DCT3E6 uses an 8-pin DCT (MSOP-8) package, 3.0 mm × 3.0 mm, 1.2 mm max height, RoHS-compliant with CuSnBi finish and JEDEC MO-187 DA compliance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar secondary Li-ion battery overvoltage protection applications.

Compared with BQ29401DCT3E6, BQ29400DCT3 offers earlier trip timing for conservative chemistries but lacks alignment with modern 4.45 V cells, while BQ29401PW delivers identical protection behavior in a larger, less dense package-requiring layout revision but no functional requalification.

Availability

BQ29401DCT3E6 is available at Aetrix Electronics and suitable for notebook PC battery management, portable medical instrumentation, and industrial test equipment requiring stable component supply and long-term lifecycle support.

Supply support for BQ29401DCT3E6 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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions across industrial, automotive, and personal electronics markets.

The BQ29401DCT3E6 belongs to TI's battery protection IC product line, designed specifically to provide hardware-based, second-level overvoltage safety for multi-cell Li-ion battery packs in portable and mission-critical applications.

FAQ

What is the overvoltage detection threshold of the BQ29401DCT3E6?

The BQ29401DCT3E6 has a fixed overvoltage detection threshold of 4.45 V ±25 mV per cell. This value is factory-trimmed and applies to any individual cell monitored via VC1–VC4 inputs. It is not adjustable and differs from other members of the bq2940x family such as the BQ29400 (4.35 V) or BQ29405 (4.65 V).

How is the delay time set on the BQ29401DCT3E6?

The delay time on the BQ29401DCT3E6 is set by an external capacitor connected to the CD pin. Using the formula t_D = (1.2 V × C_DELAY) / I_CD, where I_CD = 0.2 µA, a 0.22 µF capacitor yields ~1.32 seconds. The BQ29401DCT3E6 does not use resistors or internal registers for delay programming-only the CD capacitor determines timing.

Can the BQ29401DCT3E6 be used in a 2-cell Li-ion battery configuration?

Yes, the BQ29401DCT3E6 supports 2-cell configurations by connecting VC1, VC2, and VC3 together to the positive terminal of the top cell, and VC4 to the junction between the two cells. GND connects to the battery negative. This configuration uses only VC4–GND and VC1–VC4 differential measurements to monitor both cells independently.

What is the function of the OUT pin on the BQ29401DCT3E6?

The OUT pin on the BQ29401DCT3E6 is an open-drain output that pulls low under normal conditions and transitions high (to VDD level) when overvoltage is detected and the CD delay expires. It is designed to drive the gate of an external N-channel MOSFET, which in turn opens a fuse or disconnects the battery pack's positive rail-enabling irreversible shutdown.

Is the BQ29401DCT3E6 RoHS compliant and what is its moisture sensitivity level?

Yes, the BQ29401DCT3E6 is RoHS compliant with Pb-free (CU SNBI) finish and meets JEDEC Level-1 MSL rating at 260°C peak reflow temperature. Its packaging data confirms "Pb-Free (RoHS)" and "Level-1-260C-UNLIM" per TI's 2017 Package Option Addendum, making it suitable for standard SMT assembly without dry-pack requirements.