Texas Instruments BQ40Z50RSMT-R1

Overview

BQ40Z50RSMT-R1 from Texas Instruments is a single-chip, pack-based Li-ion/Li-polymer battery pack manager IC providing gas gauging via Impedance Track™, cell balancing, and multi-level protection (overvoltage, undervoltage, overcurrent, short-circuit, overtemperature) for 1–4 series battery packs. It integrates high-side N-CH FET drivers (CHG/DSG/PCHG), SMBus v1.1 interface, SHA-1 authentication, and LED display control. Used in notebook PCs and medical portable equipment requiring accurate state-of-charge reporting and safety-critical pack supervision.

For engineers reviewing the BQ40Z50RSMT-R1 datasheet, BQ40Z50RSMT-R1 pinout, BQ40Z50RSMT-R1 application, or BQ40Z50RSMT-R1 equivalent, key selection considerations include its 32-pin VQFN package, integrated coulomb counter with ±5.2 LSB INL, 16-bit ADC for cell voltage sensing (0.050 scaling factor), TURBO BOOST power delivery mode, and Battery Trip Point (BTP) interrupt capability.

Technical Context

The BQ40Z50RSMT-R1 implements a dual-domain analog front-end: one path for precision cell voltage monitoring (VC1–VC4, PACK, BAT) using a 16-bit ADC with programmable gain and digital filtering, and another for high-accuracy current sensing via a dedicated coulomb counter with 15-bit effective resolution and 250-ms conversion time. Its Impedance Track™ algorithm runs on an embedded microcontroller to model battery impedance and estimate available capacity under dynamic load and temperature conditions.

Protection logic executes in hardware and firmware: voltage thresholds (e.g., 4.3 V overvoltage per cell) trigger immediate CHG/DSG FET shutdown, while thermal faults use four independent thermistor inputs (TS1–TS4) and a dedicated PTC input with configurable trip resistance (1.2–3.95 MΩ). All protection events are logged in nonvolatile black-box memory for post-failure analysis.

Key Specifications

Pinout & Package

Package: 32-pin VQFN (RSM), 4.0 mm × 4.0 mm body size with exposed thermal pad - optimized for compact smart battery modules with high thermal dissipation requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ40Z50RSMT-R1, the BQ40Z60RSMT offers higher cell count support and stronger security but increases BOM cost and layout complexity, while the BQ34Z100-G1 reduces integration but shifts protection responsibility to external components - making BQ40Z50RSMT-R1 optimal for balanced cost, safety, and feature density in 1–4S portable applications.

Availability

BQ40Z50RSMT-R1 is available at Aetrix Electronics and suitable for notebook PCs, portable medical monitors, industrial handheld scanners, and test equipment requiring stable component supply, long-term lifecycle support, and validated safety compliance.

Supply support for BQ40Z50RSMT-R1 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 specializing in analog and embedded processing technologies, with leadership in power management and battery solutions.

The BQ40Z50RSMT-R1 belongs to TI's bq™ family of battery management ICs, designed specifically for intelligent, safe, and accurate Li-ion pack supervision in portable and medical applications where runtime predictability and regulatory compliance are critical.

FAQ

What is the primary function of the BQ40Z50RSMT-R1 in a battery pack?

The BQ40Z50RSMT-R1 serves as a fully integrated battery pack manager IC that performs gas gauging using Impedance Track™ technology, provides multi-level hardware and firmware protection (overvoltage, overcurrent, overtemperature), controls charge/discharge FETs, and communicates telemetry via SMBus. In every BQ40Z50RSMT-R1 implementation, it replaces discrete protection circuits and standalone fuel gauges with a single-chip solution for 1–4 series Li-ion packs.

Does the BQ40Z50RSMT-R1 support cell balancing, and how is it implemented?

Yes, the BQ40Z50RSMT-R1 supports passive cell balancing during charging or at rest using internal FET switches connected to VC1–VC4 pins. Each switch has a typical R_DS(ON) of 200 Ω, enabling controlled bleed current to equalize cell voltages. This balancing is fully managed by the BQ40Z50RSMT-R1 firmware without host intervention and is configurable via SMBus commands.

What communication interface does the BQ40Z50RSMT-R1 use, and what are its electrical characteristics?

The BQ40Z50RSMT-R1 uses an SMBus v1.1-compatible two-wire interface with SMBC and SMBD pins. It operates at up to 100 kHz, supports 1.8 V logic levels, and features 1.5 mA sink capability on outputs. Input thresholds are VIH ≥ 1.3 V and VIL ≤ 0.8 V, with 5 pF input capacitance - ensuring robust interoperability with standard system management controllers in the BQ40Z50RSMT-R1 design.

How does the BQ40Z50RSMT-R1 handle battery authentication?

The BQ40Z50RSMT-R1 implements SHA-1 authentication with dedicated secure memory for storing cryptographic keys. During pack insertion, the host system challenges the BQ40Z50RSMT-R1 to prove authenticity using these keys, preventing counterfeit battery use. This authentication is integral to the BQ40Z50RSMT-R1 silicon and requires no external components or firmware modifications.

What thermal monitoring capabilities does the BQ40Z50RSMT-R1 provide?

The BQ40Z50RSMT-R1 provides comprehensive thermal monitoring via four independent thermistor inputs (TS1–TS4), a dedicated PTC input with configurable trip resistance (1.2–3.95 MΩ), and an internal die temperature sensor (–2.0 mV/°C). All channels feed into protection algorithms and black-box logging, enabling multi-point fault detection essential for safety-critical BQ40Z50RSMT-R1 deployments.