Texas Instruments BQ7791508PW

Overview

BQ7791508PW from Texas Instruments is a stackable ultra-low power primary protector IC for 3- to 5-series Li-ion/Li-polymer battery packs, implementing autonomous voltage (±10 mV OV/±18 mV UV), current (OCD1: –3000 mV threshold, 1420 ms delay), and temperature (OTD: 65°C, OTC: 50°C) protections with integrated 50-mA passive cell balancing. It enables e-bike and power tool pack safety without MCU supervision.

For engineers reviewing the BQ7791508PW datasheet, BQ7791508PW pinout, BQ7791508PW application, or BQ7791508PW equivalent, key selection criteria include its factory-programmed 4.2 V overvoltage threshold with 100 mV hysteresis, 500-ms overcurrent discharge recovery, and TSSOP-24 package compatibility with stacked multi-device configurations up to 20-series cells.

Technical Context

The BQ7791508PW uses independent low-side NMOS CHG/DSG FET drivers with programmable gate resistors (RCHG = 1 kΩ, RDSG = 4.5 kΩ) and supports cascade stacking via LPWR→PRES interconnects. Its protection logic includes dual overcurrent discharge thresholds (OCD1/OCD2), open-wire detection on all VCx pins, and thermistor-based temperature sensing using 10-kΩ pullup + 103AT NTC at TS/VTB.

Cell balancing operates autonomously using internal FETs (8–20 Ω on-resistance) with 521-ms per-group duration and 90% duty cycle, triggered when cell voltage exceeds VCBTH by ≥50 mV above VCBTL. HIBERNATE mode entry requires 4.5 s PRES pin deglitch; exit occurs within 10 ms after PRES high assertion.

Key Specifications

Pinout & Package

TSSOP-24 package with 0.65-mm pitch; body size 7.70 mm × 4.40 mm; exposed thermal pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ7791508PW, BQ7791506PW offers faster overcurrent reaction but reduced cell balancing flexibility, while BQ7791514PW sacrifices undervoltage temperature recovery for ultra-fast fault isolation-making BQ7791508PW optimal for consumer e-mobility where balanced delay tuning and full thermal recovery are essential.

Availability

BQ7791508PW is available at Aetrix Electronics and suitable for power tools, e-bikes, and robotic vacuum cleaner designs requiring stable component supply, long-term lifecycle support, and consistent factory-programmed protection thresholds.

Supply support for BQ7791508PW 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 specializing in analog, embedded processing, and power management technologies with decades of battery management system expertise.

The BQ77915 family delivers autonomous, stackable primary protection for multi-cell Li-ion packs - designed specifically for cost-sensitive, high-volume portable power applications where MCU-free operation and ultra-low quiescent current are mandatory.

FAQ

What is the factory-programmed overvoltage threshold for BQ7791508PW?

The BQ7791508PW has a factory-programmed overvoltage threshold of 4.200 V ±10 mV with 100 mV hysteresis, optimized for standard 4.2-V Li-ion cells. This value is fixed and cannot be adjusted externally; it is verified per TI's SLUSCU0L datasheet revision L (August 2023). The BQ7791508PW uses this precise threshold to prevent cell degradation during charging without requiring host calibration.

Does BQ7791508PW support stacking beyond 5-series cells?

Yes, BQ7791508PW supports stacking up to 20-series cells using up to four devices in cascade. Each BQ7791508PW handles 3–5 series; higher counts require interconnecting LPWR→PRES and CBO→CBI pins between adjacent devices. The BQ7791508PW's design ensures consistent timing and fault propagation across the stack without additional timing compensation.

How does the HIBERNATE mode function on BQ7791508PW?

BQ7791508PW enters HIBERNATE mode when the PRES pin is left floating for ≥4.5 seconds, reducing quiescent current to 2 µA. Exit occurs within 10 ms when PRES is driven high. This mode is intended for shipping and long-term storage - the BQ7791508PW retains all programmed thresholds and state memory, resuming NORMAL operation without reset or reconfiguration.

What is the maximum cell balancing current supported by BQ7791508PW?

The BQ7791508PW delivers up to 50 mA of cell balancing current using its integrated FETs, with on-resistance specified at 8–20 Ω. For higher balancing currents, external FETs can be added - the BQ7791508PW provides dedicated CBI/CBO control signals and supports external RC filtering (RINE = 1 kΩ, CINE = 0.1 µF) per datasheet Section 8.3.

Can BQ7791508PW detect open-wire faults on all cell connections?

Yes, BQ7791508PW performs open-wire detection on all six VCx inputs (VC0–VC5) by monitoring voltage differentials between adjacent sense lines. A fault triggers when VCx falls below VCx−1 by 450–550 mV (typical), with 100-mV hysteresis. Detection delay is fixed at 4.5 seconds, and the BQ7791508PW reports the fault independently of other protections to ensure reliable pack wiring validation.