Texas Instruments BQ29400PWR

Overview

BQ29400PWR from Texas Instruments is a BiCMOS secondary overvoltage protection IC for 2-, 3-, or 4-cell Li-ion battery packs, featuring 4.35 V ±25 mV overvoltage detection threshold, <2 µA supply current, and programmable delay via external capacitor on CD pin; used in notebook PCs and portable medical equipment to blow external fuse during cell overvoltage events.

For engineers reviewing the BQ29400PWR datasheet, BQ29400PWR pinout, BQ29400PWR application, or BQ29400PWR equivalent, key selection criteria include its fixed 4.35 V protection threshold, TSSOP-8 (PW) package, 8-pin voltage-sense architecture, and role as second-level hardware safety cutoff independent of primary protection circuitry.

Technical Context

The BQ29400PWR implements precision per-cell voltage monitoring using four dedicated sense inputs (VC1–VC4) referenced to GND, with internal comparator accuracy of ±25 mV at 4.35 V. It triggers a controlled delay sequence when any sensed cell exceeds V(PROTECT), charging an external capacitor at 0.2 µA until CD reaches 1.2 V.

Upon CD threshold crossing, the open-drain OUT pin transitions high to activate an external N-channel FET that blows a fuse in the positive battery rail. Recovery occurs only after all cells fall below V(PROTECT) – 300 mV hysteresis, ensuring latch-free reset behavior under transient overvoltage conditions.

Key Specifications

Pinout & Package

TSSOP-8 (PW) package: 3.0 mm × 4.4 mm body, 0.65 mm lead pitch, 1.2 mm max height, RoHS-compliant CU-NiPdAu finish, JEDEC MO-153 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ29400PWR, BQ29401PW offers a higher, non-adjustable trip point but identical timing and interface behavior, while BD14000GUL sacrifices sensing granularity and delay flexibility for integration and size-making BQ29400PWR the only option supporting configurable 4-cell protection with sub-2 µA ICC.

Availability

BQ29400PWR is available at Aetrix Electronics and suitable for notebook PC battery packs, portable medical devices, and industrial test equipment requiring stable component supply despite its Not Recommended for New Designs (NRND) status.

Supply support for BQ29400PWR 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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions across industrial, automotive, and personal electronics markets.

The BQ29400PWR belongs to TI's battery protection IC product line, designed specifically to provide hardware-redundant, low-power secondary overvoltage cutoff for multi-cell Li-ion battery packs in safety-critical portable systems.

FAQ

What is the overvoltage protection threshold of the BQ29400PWR?

The BQ29400PWR has a fixed overvoltage detection threshold of 4.35 V ±25 mV per monitored cell. This value is factory-trimmed and not adjustable. It applies uniformly across all four sense inputs (VC1–VC4) and remains stable over the –25°C to +85°C operating temperature range. The BQ29400PWR uses this threshold to initiate the CD capacitor charging sequence when any single cell exceeds the limit.

How does the BQ29400PWR implement programmable delay for overvoltage response?

The BQ29400PWR implements programmable delay via the CD pin, which sources a precise 0.2 µA current to charge an external capacitor. When the voltage on CD reaches 1.2 V, the OUT pin activates. For example, using a 0.22 µF capacitor yields a nominal delay of 1.32 seconds (t = 1.2 V × C / 0.2 µA). The BQ29400PWR does not include internal timing components-delay is fully determined by the external capacitor value.

Can the BQ29400PWR be used in a 2-cell Li-ion battery configuration?

Yes, the BQ29400PWR supports 2-cell configurations by connecting VC1, VC2, and VC3 together to the positive terminal of the top cell, and VC4 to the junction between the two cells. The BQ29400PWR monitors the differential voltage across each cell using its internal comparator architecture. Correct connection sequencing-GND → VC4 → VC1/VC2/VC3-is mandatory to prevent false triggering, as specified in the BQ29400PWR datasheet Figure 7.

What is the supply current consumption of the BQ29400PWR under normal operation?

The BQ29400PWR draws less than 2 µA of supply current (I_CC) when all monitored cell voltages remain below the 4.35 V overvoltage threshold. This ultra-low quiescent current is measured at V_DD = 4.3 V and TA = 25°C with all sense inputs at 2.3 V. The BQ29400PWR maintains this current level across its full operating temperature range, making it suitable for long-duration battery standby applications.

Is the BQ29400PWR pin-compatible with other devices in the bq2940x family?

Yes, the BQ29400PWR shares identical pinout and package (TSSOP-8 PW) with BQ29401PW and BQ29405PW. All devices in the bq2940x family use the same VC1–VC4, GND, OUT, VDD, and CD terminal assignments and electrical interface. However, the BQ29400PWR is not functionally interchangeable without design review due to its unique 4.35 V threshold-BQ29401PW (4.45 V) and BQ29405PW (4.65 V) require corresponding system-level voltage margin adjustments.