Texas Instruments BQ771818DPJT

Overview

BQ771818DPJT from Texas Instruments is a dedicated overvoltage protection IC for 2- to 5-series Li-ion battery packs, featuring ±10 mV OVP accuracy, 4.300 V fixed overvoltage threshold, and 1 s internal delay timer. It operates across –40°C to 110°C and consumes only ≈1 µA in normal state, enabling reliable cell-level fault detection in power tool battery management systems.

For engineers reviewing the BQ771818DPJT datasheet, BQ771818DPJT pinout, BQ771818DPJT application, or BQ771818DPJT equivalent, key selection criteria include its CMOS active-high output drive, 8-pin QFN (3.00 mm × 4.00 mm) package, low 100 nA per-cell input leakage, functional safety documentation support, and compatibility with handheld power tools requiring fast, accurate overvoltage response.

Technical Context

The BQ771818DPJT independently monitors up to five differential cell voltages (V1–VSS through V5–V4) using precision internal references. Upon detecting any cell voltage exceeding 4.300 V, it initiates a fixed 1 s delay timer before asserting the CMOS active-high OUT signal.

Its sensing architecture requires external RC filters on each Vx input and VDD, with design-critical RIN = 1 kΩ for calibrated OVP accuracy. The device supports Customer Test Mode (CTM) with sub-15 ms fault detection for production-line validation, while maintaining functional safety capability per ISO 26262 system-level development guidance.

Key Specifications

Pinout & Package

Package: 8-pin WSON (QFN), 3.00 mm × 4.00 mm, wettable flank, RoHS-compliant, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ771801DPJT and BQ771802DPJT, the BQ771818DPJT offers a higher 4.300 V trip point optimized for standard NMC Li-ion cells, eliminates external pull-up requirements via CMOS active-high output, and simplifies PCB routing and firmware interrupt handling in space-constrained battery packs.

Availability

BQ771818DPJT is available at Aetrix Electronics and suitable for handheld power tools, cordless vacuum cleaners, light electric vehicles, and UPS battery backup systems requiring stable component supply, long-term lifecycle support, and functional safety documentation.

Supply support for BQ771818DPJT 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 delivering analog and embedded processing solutions, with leadership in battery management ICs and functional safety infrastructure.

The BQ7718 family is designed specifically for standalone overvoltage protection in multi-cell Li-ion battery packs, targeting cost-sensitive, high-reliability applications where precision, low power, and production test efficiency are critical.

FAQ

What is the overvoltage protection threshold and accuracy of the BQ771818DPJT?

The BQ771818DPJT has a fixed overvoltage protection threshold of 4.300 V with ±10 mV accuracy at 25°C. Its accuracy degrades to ±44 mV over the full –40°C to 110°C operating range, as specified in the DC characteristics table. This precision enables reliable detection of overvoltage conditions in standard NMC-based 2–5S Li-ion battery packs without external calibration. The BQ771818DPJT maintains this performance using factory-trimmed internal references and matched sensing circuitry.

Does the BQ771818DPJT support Customer Test Mode (CTM), and how is it activated?

Yes, the BQ771818DPJT supports Customer Test Mode (CTM) to reduce production-line test time. CTM is activated by applying VDD at least 10 V higher than the V5 pin voltage, which shortens the overvoltage delay to less than 15 ms. The BQ771818DPJT exits CTM automatically when the VDD-to-V5 differential drops below 10 V. This feature allows rapid validation of OVP functionality without modifying hardware or firmware, and is documented in Section 8.4.3 of the BQ771818DPJT datasheet.

What package type and footprint does the BQ771818DPJT use?

The BQ771818DPJT uses an 8-pin WSON (QFN) package designated DPJ, with nominal dimensions of 3.00 mm × 4.00 mm and wettable flanks for automated optical inspection. It is RoHS-compliant, rated MSL Level-1, and compatible with standard reflow profiles. The BQ771818DPJT pinout places VDD and VSS on opposite corners, with V1–V5 arranged sequentially for straightforward daisy-chain PCB routing in multi-cell battery monitor layouts.

How does the BQ771818DPJT handle cell voltage sensing and what external components are required?

The BQ771818DPJT senses each cell's differential voltage independently using dedicated Vx inputs (V1–V5), requiring a 1 kΩ resistor and 0.1 µF capacitor on each input for noise filtering and stability. The BQ771818DPJT's OVP accuracy is calibrated for RIN = 1 kΩ - deviations introduce measurable error in trip voltage. VDD also requires a series resistor and bypass capacitor. These RC networks are mandatory for proper operation and are detailed in Figure 9-1 and Table 9-1 of the BQ771818DPJT datasheet.

Is the BQ771818DPJT functional safety-capable, and what documentation is available?

Yes, the BQ771818DPJT is functional safety-capable, with documentation available to aid ISO 26262 system-level safety design. This includes FIT rate data, failure mode effect analysis (FMEA), and diagnostic coverage guidance - not just generic statements. The BQ771818DPJT's architecture supports safety mechanisms such as redundant sensing paths and predictable fault response timing (1 s delay), and TI provides dedicated safety manuals for the BQ7718 family to support ASIL-B development workflows.