Texas Instruments BQ29412PWG4

Overview

BQ29412PWG4 from Texas Instruments is a secondary overvoltage protection IC for 2-, 3-, or 4-cell Li-ion battery packs, featuring fixed 4.45 V per-cell overvoltage threshold, programmable delay via external capacitor on CD pin, and ultra-low 2 µA supply current. It monitors individual cell voltages (VC1–VC4), activates OUT high upon overvoltage detection, and drives external fuse-blowing circuitry in notebook and portable instrumentation battery systems.

For engineers reviewing the BQ29412PWG4 datasheet, BQ29412PWG4 pinout, BQ29412PWG4 application, or BQ29412PWG4 equivalent, key selection factors include its 4.45 V precision overvoltage trip point, ±80 mV accuracy over –40°C to 110°C, 1–2 s programmable delay with 0.22 µF capacitor, TSSOP-8 (PW) package, and role as second-level hardware safety guard in multi-cell Li-ion packs.

Technical Context

The BQ29412PWG4 implements independent voltage monitoring across up to four series-connected Li-ion cells using dedicated VC1–VC4 inputs, comparing each against an internal reference to detect overvoltage. Its protection sequence initiates when any single cell exceeds 4.45 V, triggering a constant-current (0.18 µA) charge of the external CD capacitor until 1.2 V is reached.

Upon CD pin reaching 1.2 V, the open-drain OUT pin transitions high to enable an external N-channel FET that blows the main fuse in the battery's positive rail. Recovery requires all cell voltages to fall below 4.45 V minus 320 mV hysteresis before OUT resets low.

Key Specifications

Pinout & Package

TSSOP-8 (PW) package: 3.0 mm × 4.4 mm, 1.2 mm max height, lead pitch 0.65 mm, RoHS-compliant CU-NiPdAu finish, MSL Level-2-260°C-1 year.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ29412PWG4, BQ29411PWG4 provides earlier overvoltage cutoff (4.40 V vs. 4.45 V) for conservative safety margins, while BQ29413PWG4 delays action to 4.50 V-enabling compatibility with high-accuracy chargers or aged cells-without altering PCB layout or timing behavior.

Availability

BQ29412PWG4 is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, and medical handheld devices requiring stable component supply for legacy battery management designs.

Supply support for BQ29412PWG4 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.

The bq2941x family was designed specifically for hardware-based secondary overvoltage protection in multi-cell Li-ion battery packs, delivering precision analog monitoring independent of host microcontroller control.

FAQ

What is the exact overvoltage protection threshold of the BQ29412PWG4?

The BQ29412PWG4 has a fixed overvoltage protection threshold of 4.45 V per cell, with accuracy of ±25 mV at 25°C and ±80 mV over the full –40°C to 110°C operating range. This value is factory-trimmed and does not require external configuration. The BQ29412PWG4 uses this threshold to initiate the CD capacitor charging sequence when any monitored cell exceeds it.

How does the BQ29412PWG4 implement programmable delay time?

The BQ29412PWG4 implements programmable delay via its CD pin, which sources a constant 0.18 µA current to charge an external capacitor. When the CD pin voltage reaches 1.2 V, the OUT pin activates. Using a 0.22 µF capacitor yields a nominal delay of 1.5 seconds (t_D = 1.2 V × C_DELAY / 0.18 µA). The BQ29412PWG4 supports delay tuning across 1–2 s by adjusting capacitance.

Is the BQ29412PWG4 pin-compatible with other bq2941x variants?

Yes, the BQ29412PWG4 is fully pin-compatible with all bq2941x family members-including BQ29410PWG4, BQ29411PWG4, BQ29413PWG4, and BQ29414PWG4-in both TSSOP-8 (PW) and MSOP-8 (DCT) packages. All share identical pinout, electrical interface, and functional timing; only the overvoltage threshold differs (4.30–4.60 V). No PCB changes are needed when substituting within the family.

What is the recommended operating temperature range for the BQ29412PWG4?

The BQ29412PWG4 is rated for operation from –40°C to +110°C ambient temperature, with guaranteed overvoltage detection accuracy and delay timing performance across this full industrial range. Its thermal design supports placement directly on battery module PCBs near cell connections, and the TSSOP-8 package provides adequate power dissipation (273 mW at 85°C) without heatsinking.

Does the BQ29412PWG4 require external passive components for basic operation?

Yes, the BQ29412PWG4 requires three external components for standard operation: a 0.22 µF capacitor on the CD pin for delay timing, a pull-up resistor (typically 10 kΩ) on the open-drain OUT pin, and optional RC filters (R_IN/C_IN and R_VD/C_VD) on VCx and VDD lines for noise immunity. These are explicitly specified in the BQ29412PWG4 datasheet and required for reliable overvoltage detection.