Texas Instruments BQ29411DCTT

Overview

BQ29411DCTT 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, <2 µA supply current, and programmable delay via external capacitor on CD pin. It monitors individual cell voltages (VC1–VC4), triggers OUT high to activate external fuse-blowing circuitry upon overvoltage, and supports notebook computers and portable instrumentation.

For engineers reviewing the BQ29411DCTT datasheet, BQ29411DCTT pinout, BQ29411DCTT application, or BQ29411DCTT equivalent, key selection criteria include per-cell voltage threshold accuracy (±50 mV over –20°C to 85°C), low ICC (<2 µA), CD-pin-based delay timing (1–2 s with 0.22 µF), and compatibility with DCT 8-pin MSOP package in space-constrained battery management systems.

Technical Context

The BQ29411DCTT implements independent voltage monitoring across up to four series-connected Li-ion cells using precision comparators referenced to an internal bandgap. Each VCn input (VC1–VC4) senses a specific cell's voltage relative to adjacent nodes, enabling detection of overvoltage on any single cell without requiring full pack voltage measurement.

Upon detection of any cell exceeding 4.40 V, an internal 0.18 µA current source charges the external capacitor at CD, and when CD reaches 1.2 V, the open-drain OUT pin transitions high to drive an external N-channel FET. The device includes 250–320 mV hysteresis and maintains stable operation during pulse charging and under high supply ripple conditions.

Key Specifications

Pinout & Package

Package: SSOP-8 (DCT), 3.0 mm × 3.0 mm × 1.3 mm body, 0.65 mm pitch, moisture sensitivity level 1, RoHS-compliant NiPdAu lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ29411DCTT, BQ29412DCTT raises protection by 50 mV for higher-energy cells, while BQ29410DCTT lowers it by 50 mV for aging-sensitive deployments-both preserve identical PCB layout, timing behavior, and thermal performance.

Availability

BQ29411DCTT is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, and medical portable devices requiring stable component supply with guaranteed long-term lifecycle support.

Supply support for BQ29411DCTT 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, embedded processing, and power management technologies, with over 50 years of leadership in precision analog ICs.

The bq2941x family was designed specifically for secondary overvoltage protection in multi-cell Li-ion battery packs, delivering hardware-enforced safety without MCU dependency or external passive components.

FAQ

What is the exact overvoltage protection threshold of the BQ29411DCTT?

The BQ29411DCTT has a fixed overvoltage protection threshold of 4.40 V per cell, specified with ±50 mV accuracy over –20°C to 85°C ambient temperature. This value is factory-trimmed and non-adjustable, ensuring consistent secondary protection behavior across production lots without calibration.

How does the BQ29411DCTT implement programmable delay time?

The BQ29411DCTT 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 activates. With a 0.22 µF capacitor, delay time is 1–2 seconds; scaling CDELAY linearly adjusts timing per td = (1.2 V × CDELAY) / 0.18 µA.

Can the BQ29411DCTT be used in a 2-cell Li-ion configuration?

Yes, the BQ29411DCTT supports 2-cell configurations by connecting VC1 = VC2 = VC3 = VDD and VC4 to the bottom of the stack (cell 2 cathode), with GND completing the reference. The device automatically adapts sensing to the active cell count without external configuration pins or firmware.

What is the maximum operating voltage range for the VC1–VC4 inputs of the BQ29411DCTT?

The VC1–VC4 inputs of the BQ29411DCTT accept voltages from 0 V to 25 V each, with differential voltage limits of –0.3 V to 8 V between adjacent sense terminals (e.g., VC1–VC2). This supports full 4S Li-ion packs (up to ~16.8 V) plus margin for transient overshoot.

Does the BQ29411DCTT require external passive components for basic operation?

Yes - the BQ29411DCTT requires an external 0.22 µF capacitor on the CD pin for delay timing and a pull-up resistor on the open-drain OUT pin to interface with the external N-channel FET gate. No external resistors are needed for voltage threshold setting, as it is internally fixed at 4.40 V.