Texas Instruments BQ29449DRBR

Overview

BQ29449DRBR from Texas Instruments is a second-level overvoltage protection IC for 2-, 3-, or 4-series Li-ion battery packs, featuring fixed 4.30 V overvoltage threshold, ±25 mV accuracy (0°C to 60°C), <2 µA typical supply current, and external capacitor-controlled delay timing. It operates across –40°C to +110°C and is used in notebook computers and power tools for cell-level voltage monitoring and fault-triggered output assertion.

For engineers reviewing the BQ29449DRBR datasheet, BQ29449DRBR pinout, BQ29449DRBR application, or BQ29449DRBR equivalent, key selection criteria include its 4.30 V OVP threshold, DRB 8-pin QFN package with exposed thermal pad, non-latching OUT behavior, 9.0 s/µF delay scale factor, and compatibility with multi-cell stack topologies requiring secondary protection redundancy.

Technical Context

The BQ29449DRBR implements precision per-cell voltage monitoring using internal high-accuracy comparators referenced to a stable bandgap. Each VCx pin independently senses inter-cell voltage differences (VC1–VC2, VC2–VC3, VC3–VC4, VC4–GND) up to 5 V, triggering protection when any exceeds 4.30 V ±25 mV.

Upon overvoltage detection, a 140 nA current source charges the external CD capacitor; when voltage at CD reaches 1.2 V, the open-drain OUT pin pulls high (≤9.5 V, IOH = 0 mA). The device supports Customer Test Mode (CTM) with reduced 0.08 s/µF delay scaling for accelerated production verification.

Key Specifications

Pinout & Package

Package: DRB - 8-pin 3.0 mm × 3.0 mm SON (Small Outline No-Lead) with exposed thermal pad; requires soldering of thermal pad for thermal and mechanical reliability per TI SLUA271 guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ29449DRBR, BQ29441DRBR offers a 100 mV higher OVP threshold for wider chemistry compatibility but identical timing and packaging, while BD8637GUL trades configurability and 4-series flexibility for ultra-small footprint and integrated drive-making it unsuitable as a drop-in replacement.

Availability

BQ29449DRBR is available at Aetrix Electronics and suitable for notebook computers, power tools, and portable medical devices requiring stable component supply across long-life industrial programs.

Supply support for BQ29449DRBR 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 battery management and power ICs.

The bq2944x family was designed specifically for secondary overvoltage protection in multi-cell Li-ion battery packs, emphasizing accuracy, ultra-low quiescent current, and field-configurable timing without MCU dependency.

FAQ

What is the overvoltage protection threshold of the BQ29449DRBR?

The BQ29449DRBR has a fixed overvoltage protection threshold of 4.30 V with ±25 mV accuracy over 0°C to 60°C. This value is factory-trimmed and not user-adjustable. It applies to each monitored cell voltage (VC1–VC2, VC2–VC3, VC3–VC4, VC4–GND), and the device triggers protection if any single cell exceeds this threshold. The BQ29449DRBR does not support alternative thresholds-other variants like BQ29441DRBR offer 4.40 V, but those are distinct part numbers.

Does the BQ29449DRBR provide latched or non-latched overvoltage output behavior?

The BQ29449DRBR provides non-latched output behavior: the OUT pin transitions high after the CD capacitor charges to 1.2 V during an overvoltage event, but returns low automatically once all cell voltages fall below the 4.30 V threshold and the CD capacitor discharges. Unlike the BQ2944L9 variant, the BQ29449DRBR has no internal latch-no external shorting of CD to GND is required for reset. This simplifies system recovery in applications requiring automatic resumption after transient overvoltage.

How is the overvoltage delay time set on the BQ29449DRBR?

The overvoltage delay time on the BQ29449DRBR is set by an external capacitor connected to the CD pin. A 140 nA internal current source charges this capacitor; when voltage reaches 1.2 V, OUT asserts high. With a nominal delay scale factor of 9.0 s/µF, a 0.33 µF capacitor yields ~3 s delay. The BQ29449DRBR supports Customer Test Mode (CTM), reducing the scale factor to 0.08 s/µF for accelerated validation-activated by setting VDD ≈ 9.5 V above VC1.

What package type and thermal requirements apply to the BQ29449DRBR?

The BQ29449DRBR uses the DRB package: an 8-pin 3.0 mm × 3.0 mm SON (Small Outline No-Lead) with exposed thermal pad. Per TI documentation, the thermal pad must be soldered to the PCB for mechanical integrity and thermal performance. Recommended layout follows TI SLUA271 guidelines, including 81% solder paste coverage on the thermal pad and optional vias filled or tented. The junction-to-board thermal resistance is 19.3°C/W, confirming effective heat dissipation through the pad.

Can the BQ29449DRBR monitor 2-series, 3-series, and 4-series Li-ion battery configurations?

Yes, the BQ29449DRBR supports 2-, 3-, and 4-series Li-ion battery configurations via its five voltage sense inputs: VC1 (top cell), VC2 (second cell), VC3 (third cell), VC4 (bottom cell), and GND. For 2-series use, only VC1, VC2, and GND are connected; for 3-series, VC1–VC3 and GND; for 4-series, all four VCx pins plus GND. The datasheet explicitly confirms interoperability across all three topologies, and the pinout is identical regardless of stack size-no configuration pins or mode selection are required.