Texas Instruments BQ78350DBT

Overview

BQ78350DBT from Texas Instruments is a Li-ion/LiFePO₄ battery management controller and fuel gauge companion to the bq769x0 AFE family, providing CEDV-based state-of-charge estimation, lifetime data logging, SMBus 1.1 host communication, and full voltage/current/temperature protection for 3–15-series cell packs up to 320 Ahr in e-bikes, power tools, and UPS systems.

For engineers reviewing the BQ78350DBT datasheet, BQ78350DBT pinout, BQ78350DBT application, or BQ78350DBT equivalent, key selection considerations include its 30-pin TSSOP (DBT) package, dual-oscillator architecture (4.194 MHz + 32.768 kHz), 16-bit ADC with ±0.03% FSR INL, 10-year data flash retention, and SHA-1 authentication support for secure battery pack identification.

Technical Context

The BQ78350DBT implements a CoolRISC CPU with integrated delta-sigma ADC and coulomb counter, interfacing exclusively via SMBus 1.1 (slave-only) to host controllers while coordinating real-time protection decisions with the bq769x0 AFE over dedicated SDA/SCL lines. It supports configurable safety levels - primary (cell-level OV/UV, OC, OT/UT) and secondary (SAFE pin-triggered fuse blow) - with independent thresholds per thermistor channel.

Its fuel gauging relies on Compensated End-of-Discharge Voltage (CEDV) algorithm, integrating current measurements from the bq769x0's 15-bit bipolar integrating ADC (±0.2 V range, 15 µV resolution), compensating for temperature and SoC drift, and estimating self-discharge dynamically. Lifetime logging stores 12 safety events, cycle count, min/max cell voltages, and thermal extremes in non-volatile memory.

Key Specifications

Pinout & Package

Package: 30-pin TSSOP (DBT), 7.80 mm × 6.40 mm body size, surface-mount, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ78350DBT, the BQ78350-R1 offers improved ESD immunity and updated gauging models but requires layout changes for POR network adjustment, while MAX17055 reduces BOM count in low-channel-count applications but forfeits AFE synchronization and secondary safety enforcement.

Availability

BQ78350DBT is available at Aetrix Electronics and suitable for electric bicycles, cordless power tools, and uninterruptible power supply systems requiring stable component supply, long-term lifecycle support, and traceable sourcing for industrial-grade battery packs.

Supply support for BQ78350DBT 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 innovation.

The BQ78350DBT belongs to TI's bq783xx fuel gauge and BMS controller product line, designed specifically to complement the bq769x0 AFE family for scalable, high-accuracy Li-ion and LiFePO₄ battery pack monitoring and protection.

FAQ

What is the primary function of the BQ78350DBT in a battery management system?

The BQ78350DBT serves as a fuel gauge and battery management controller that works exclusively with the bq769x0 AFE family. It performs CEDV-based state-of-charge estimation, lifetime data logging, SMBus 1.1 host communication, and coordinated voltage/current/temperature protection. The BQ78350DBT does not measure cells directly but processes digitized data from the AFE to execute gauging algorithms and protection decisions.

Does the BQ78350DBT support standalone operation without the bq769x0 AFE?

No, the BQ78350DBT requires the bq769x0 AFE (bq76920, bq76930, or bq76940) to function. It has no internal cell voltage or current sensing circuitry. All analog measurements - including cell voltages, current via SRP/SRN, and thermistor readings - are performed by the AFE and communicated to the BQ78350DBT over the dedicated SDA/SCL interface. The BQ78350DBT cannot operate as a standalone fuel gauge.

What are the key timing specifications for SMBus communication with the BQ78350DBT?

The BQ78350DBT complies with SMBus 1.1 timing: clock frequency 10–100 kHz, data hold time ≥300 ns, data setup time ≥250 ns, and bus free time ≥4.7 ms. It supports packet error checking (PEC) and operates as a slave only. The device times out transactions if clock low exceeds 25–35 ms, ensuring robustness against bus hangs in noisy industrial environments.

How does the BQ78350DBT handle battery pack authentication?

The BQ78350DBT implements SHA-1 cryptographic authentication per SMBus command. When queried by a host, it generates a challenge-response signature using a unique 160-bit key stored in one-time-programmable memory. This enables OEMs to verify genuine TI battery modules and prevent unauthorized third-party packs from operating in certified equipment - a feature confirmed in the SLUSB48 datasheet Section 9.3.6.

What is the role of the SAFE pin on the BQ78350DBT?

The SAFE pin is an active-high, secondary-level safety output used to trigger irreversible actions such as blowing an external fuse or disabling charge/discharge paths upon critical faults - including cell imbalance, AFE communication failure, or safety overvoltage. Unlike primary protections (e.g., ALERT), SAFE asserts only after redundancy checks and is intended for catastrophic fault containment, as defined in Section 9.3.2 of the BQ78350DBT datasheet.