Texas Instruments BQ29411PWG4

Overview

BQ29411PWG4 from Texas Instruments is a secondary overvoltage protection IC for 2-, 3-, or 4-cell Li-ion battery packs, featuring fixed 4.40 V per-cell overvoltage threshold, programmable delay via external capacitor on CD pin, and ultra-low 2 µA supply current. It monitors individual cell voltages (VC1–VC4), activates OUT high to trigger external fuse blow when overvoltage occurs, and supports stable operation during pulse charging in portable instrumentation.

For engineers reviewing the BQ29411PWG4 datasheet, BQ29411PWG4 pinout, BQ29411PWG4 application, or BQ29411PWG4 equivalent, key selection criteria include its precise 4.40 V overvoltage detection accuracy (±25 mV at 25°C), 1.2 V CD-pin delay trigger threshold, 8-pin TSSOP (PW) package compatibility, and second-level protection role in battery management systems requiring fail-safe redundancy.

Technical Context

The BQ29411PWG4 implements independent voltage monitoring across up to four series-connected Li-ion cells using dedicated VC1–VC4 inputs, with internal precision reference comparison and hysteresis of 320 mV. Its protection sequence initiates only when any single cell exceeds 4.40 V, triggering a current source (0.18 µA nominal) to charge an external capacitor on CD.

Delay time is determined by t_D = (1.2 V × C_DELAY) / I_CD, where C_DELAY ranges from 0.22 µF to achieve 1–2 s typical delay. The OUT pin drives high (≥2.5 V at 40 µA sink) to control an external N-channel FET, enabling fuse activation in the positive battery rail without requiring continuous power from the protected pack.

Key Specifications

Pinout & Package

Package: 8-pin TSSOP (PW), 3.0 mm × 4.4 mm body, 0.65 mm pitch, RoHS-compliant green finish (CU NIPDAU), MSL Level-2-260C-1 YEAR.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar secondary overvoltage protection applications.

Compared with BQ29412PWG4, the BQ29411PWG4 provides earlier overvoltage intervention at 4.40 V-critical for aging cells prone to swelling-and compared with MP26028DJ-LF-Z, it delivers true multi-cell independence and field-configurable delay timing essential for industrial battery packs.

Availability

BQ29411PWG4 is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, medical portable devices, and industrial handheld scanners requiring stable component supply with guaranteed long-term manufacturability.

Supply support for BQ29411PWG4 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 leader delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.

The BQ29411PWG4 belongs to TI's bq2941x family of secondary protection ICs, designed specifically to provide hardware-enforced, cell-level overvoltage safety in multi-cell Li-ion battery packs where primary BMS may fail or lack redundancy.

FAQ

What is the exact overvoltage protection threshold of the BQ29411PWG4?

The BQ29411PWG4 has a fixed, factory-trimmed overvoltage protection threshold of 4.40 V per cell, specified with ±25 mV accuracy at 25°C and ±80 mV over –40°C to 110°C. This value is laser-trimmed during production and does not require external calibration or resistor networks. The BQ29411PWG4 maintains this threshold across its full operating temperature range and supply voltage (4 V to 25 V), making it suitable for safety-critical battery applications where predictable trip points are mandatory.

How does the BQ29411PWG4 implement programmable delay time?

The BQ29411PWG4 uses an internal 0.18 µA current source to charge an external capacitor connected to the CD pin; when the CD voltage reaches 1.2 V, the OUT pin transitions high. Delay time is calculated as t_D = (1.2 V × C_DELAY) / 0.18 µA-for example, a 0.22 µF capacitor yields ~1.5 s typical delay. The BQ29411PWG4 clamps CD to GND if overvoltage clears before threshold is reached, preserving full delay for subsequent events. This method avoids reliance on RC tolerances or temperature drift.

Can the BQ29411PWG4 be used in a 2-cell Li-ion battery configuration?

Yes, the BQ29411PWG4 supports 2-cell configurations by connecting VC1, VC2, and VC3 together to the positive terminal of the top cell, and VC4 to the positive terminal of the bottom cell, with GND at the battery negative. In this setup, the BQ29411PWG4 compares the summed voltage across both cells against its 4.40 V threshold per cell-i.e., total pack voltage must exceed 8.80 V to trigger protection. The device's architecture allows seamless reconfiguration between 2S, 3S, and 4S without firmware or hardware changes.

What is the function of the OUT pin on the BQ29411PWG4?

The OUT pin on the BQ29411PWG4 is an open-drain output that transitions high (to VDD level) when any monitored cell exceeds 4.40 V and the CD pin delay expires. It is designed to drive the gate of an external N-channel MOSFET, which in turn activates a fuse in the positive battery rail. After overvoltage clears and all cells fall below (4.40 V – 320 mV hysteresis), OUT returns low. The BQ29411PWG4 specifies 2.5 V minimum high-level voltage at 40 µA sink, ensuring robust interface with common logic-level FETs.

Does the BQ29411PWG4 require external passive components for basic operation?

Yes-the BQ29411PWG4 requires at minimum an external capacitor on the CD pin to set overvoltage delay time (0.22 µF typical), plus optional RC filters on VC pins (R_IN = 100 Ω–1 kΩ, C_IN = 0.01–0.1 µF) and VDD (R_VD = 0–1 kΩ, C_VD = 0.1 µF) for noise immunity. No external resistors are needed for voltage threshold setting, as the 4.40 V reference is internal and trimmed. All required passive values are specified in the BQ29411PWG4 datasheet's recommended operating conditions table.