Texas Instruments BQ7790400PW

Overview

BQ7790400PW from Texas Instruments is a factory-programmed, ultra-low-power lithium-ion battery protector for 3- to 4-series cell packs, implementing independent overvoltage (4225 mV), undervoltage (2200 mV), open-wire, and dual-stage overcurrent discharge (OCD1: 40 mV; OCD2: 100 mV) protections without MCU intervention. It integrates low-side NMOS CHG and DSG FET drivers and supports cascaded stackable configurations for higher-cell-count systems.

For engineers reviewing the BQ7790400PW datasheet, BQ7790400PW pinout, BQ7790400PW application, or BQ7790400PW equivalent, this device delivers verified ±10 mV voltage protection accuracy, 6 µA normal-mode current, 2-s OV/UV delay timing, and load-removal recovery - critical for power tool, E-bike, and UPS battery pack safety design.

Technical Context

The BQ7790400PW operates as a standalone analog protection IC with no firmware or communication interface. Its protection logic uses internal comparators with factory-trimmed thresholds and fixed delay timers - including 2 s for overvoltage and undervoltage detection, 350 ms for OCD2, and 0 s for short-circuit discharge recovery - all implemented without external components or host control.

It features dual independent FET drivers (CHG and DSG) with 12 V typical on-voltage at ≥12 V VDD, 0.5 kΩ CHG off-resistance, and 10–16 Ω DSG off-resistance. The device supports cascading via CTRC/CTRD pins and uses VC1–VC5 inputs for cell voltage monitoring, with VC5 internally tied to VC4 in BQ77904 variants.

Key Specifications

Pinout & Package

Package: 20-pin TSSOP (PW), 6.50 mm × 4.40 mm body size, with exposed thermal pad (not electrically connected).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar lithium-ion battery protection applications.

Compared with BQ7790400PW, BQ7790500PW extends cell count support and tightens overvoltage timing but reduces OCD2 threshold sensitivity; BD41060FV offers lower quiescent current but sacrifices standalone operation and field-proven stackability in industrial battery systems.

Availability

BQ7790400PW is available at Aetrix Electronics and suitable for power tools, light electric vehicles, and energy storage systems requiring stable component supply, long-term lifecycle support, and automotive-grade reliability.

Supply support for BQ7790400PW 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 experience in battery management solutions.

The BQ77904 product line delivers autonomous, stackable, ultra-low-power protection for lithium-based battery packs - designed specifically for cost-sensitive, high-reliability applications where MCU-free safety is mandatory.

FAQ

What is the overvoltage protection threshold and accuracy of the BQ7790400PW?

The BQ7790400PW has a factory-programmed overvoltage threshold of 4225 mV with ±10 mV accuracy at 25°C, degrading to ±40 mV across –40°C to +85°C. This precision prevents Li-ion cell overcharge while allowing full utilization of the 4.2 V nominal range. The BQ7790400PW implements hysteresis of 100 mV to avoid oscillation near trip point.

Does the BQ7790400PW support stacking for battery packs with more than four series cells?

Yes, the BQ7790400PW supports cascaded stacking via its CTRC and CTRD pins to protect battery packs with up to 20 series cells. In a stack, the upper device's CHGU output connects to the lower device's CTRC pin, enabling synchronized CHG/DSG control. The BQ7790400PW itself is rated for 3S–4S, but functions as the bottom device in larger configurations.

What is the purpose of the LD pin on the BQ7790400PW?

The LD (Load Detection) pin on the BQ7790400PW senses disconnection of the PACK– terminal. When voltage at LD falls below 1.3 V, the device recognizes load removal and enables automatic recovery after fault conditions clear - eliminating need for manual reset in portable tools or UPS systems. This behavior is enabled by default in the BQ7790400PW configuration.

How does the BQ7790400PW handle overcurrent detection stages?

The BQ7790400PW implements two independent overcurrent discharge stages: OCD1 triggers at 40 mV (e.g., 20 A with 2 mΩ sense resistor) with configurable delays from 10 ms to 1420 ms, while OCD2 trips at 100 mV (e.g., 50 A) with 350-ms fixed delay. Both use (SRP – SRN) differential sensing and recover automatically after load removal - a key feature of the BQ7790400PW design.

Is the BQ7790400PW compatible with NTC thermistors for temperature monitoring?

Yes, the BQ7790400PW interfaces directly with standard 10-kΩ NTC thermistors via the TS pin, using VTB (3.0 V bias output) to form a voltage divider. Temperature thresholds - such as OTD=70°C and UTC=–5°C - are defined as ratios of VTB (e.g., 20.56% VTB for 70°C), enabling accurate, resistor-free calibration. This analog thermistor interface is integral to the BQ7790400PW's MCU-free operation.