Texas Instruments BQ29440DRBT

Overview

BQ29440DRBT from Texas Instruments is a second-level overvoltage protection IC for 2-, 3-, or 4-series Li-ion battery packs, featuring fixed 4.35 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 delivers precise cell voltage monitoring in notebook computers and power tools.

For engineers reviewing the BQ29440DRBT datasheet, BQ29440DRBT pinout, BQ29440DRBT application, or BQ29440DRBT equivalent, key selection criteria include overvoltage threshold accuracy, latch-free operation, QFN-8 package thermal performance, and compatibility with multi-cell battery management systems requiring secondary protection.

Technical Context

The BQ29440DRBT continuously monitors individual cell voltages via VC1–VC4 inputs using high-accuracy comparators referenced to an internal 4.35 V threshold. When any cell exceeds VPROTECT, a 140 nA current source charges the external CD capacitor until it reaches 1.2 V, triggering OUT high after a delay scalable by capacitor value.

No internal latch is implemented - the OUT pin returns low once overvoltage clears and the CD capacitor fully discharges. The device supports 2–4 series configurations with independent voltage sensing per cell and operates with VDD from 4 V to 25 V, enabling integration into compact, thermally constrained battery packs.

Key Specifications

Pinout & Package

8-pin SON (DRB) package with 0.65 mm pitch, 2.9 mm × 2.9 mm body, and exposed thermal pad soldered to PCB for thermal and mechanical stability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ29441DRBT and BQ29449DRBT, the BQ29440DRBT offers the industry-standard 4.35 V threshold balancing cell longevity and safety - making it the default choice for conventional 3.6 V nominal Li-ion packs in consumer and industrial equipment.

Availability

BQ29440DRBT is available at Aetrix Electronics and suitable for notebook computers, power tools, and portable medical devices requiring stable component supply and long-term lifecycle support.

Supply support for BQ29440DRBT 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 solutions.

The bq2944x product line delivers precision secondary overvoltage protection for multi-cell Li-ion battery packs, targeting applications where reliability, low power, and configurable timing are essential for functional safety compliance.

FAQ

What is the overvoltage protection threshold of the BQ29440DRBT?

The BQ29440DRBT has a fixed overvoltage protection threshold of 4.35 V with ±25 mV accuracy over 0°C to 60°C. This value is factory-trimmed and non-adjustable. It applies to each monitored cell voltage (VC1–VC2, VC2–VC3, VC3–VC4, and VC4–GND), and the BQ29440DRBT triggers protection if any single cell exceeds this threshold.

Does the BQ29440DRBT include an internal latch function?

No, the BQ29440DRBT does not include an internal latch. It is a non-latching variant - the OUT pin returns to low once the overvoltage condition is removed and the CD capacitor discharges fully. Latching behavior is only available in the BQ2944L0 and BQ2944L9 variants, which are explicitly marked with "L" in the part number.

How is the overvoltage delay time set on the BQ29440DRBT?

The overvoltage delay time on the BQ29440DRBT is set using an external capacitor connected to the CD pin. With a nominal scale factor of 9.0 s/µF, a 0.33 µF capacitor yields ~3 seconds delay. The internal 140 nA current source charges the capacitor to 1.2 V, at which point OUT transitions high. Delay time varies ±15% across temperature due to XDELAY specification limits.

What package type and dimensions does the BQ29440DRBT use?

The BQ29440DRBT uses an 8-pin SON (DRB) package measuring 2.9 mm × 2.9 mm with 0.65 mm pitch and 1 mm max height. It features an exposed thermal pad on the bottom for PCB soldering, providing θ_JB = 19.3°C/W. The DRB marking appears on the top surface, and pin 1 is located in quadrant Q2 per tape-and-reel orientation.

Can the BQ29440DRBT monitor 2-cell, 3-cell, and 4-cell Li-ion battery configurations?

Yes, the BQ29440DRBT supports 2-, 3-, and 4-series Li-ion battery configurations using its VC1–VC4 inputs. For 2-cell packs, only VC1, VC2, and GND are used; for 3-cell, VC1–VC3 and GND; for 4-cell, all four VC pins plus GND. The device automatically adapts sensing range and does not require configuration pins or firmware.