What Are the Key Features of Texas Instruments BQ25628 and BQ25629 Charger ICs?

The Texas Instruments BQ25628 and BQ25629 are advanced battery charger ICs designed for single-cell Li-Ion/Li-Polymer batteries. They support fast charging up to 3A, integrate a narrow-voltage DC/DC converter, and offer programmable thermal management. These ICs are optimized for portable devices, providing high efficiency, compact size, and robust safety features like over-voltage and over-current protection.

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How Do BQ25628 and BQ25629 Enhance Charging Efficiency?

The ICs use a switch-mode buck charger architecture with 1.5MHz switching frequency, reducing power loss and heat generation. Their input current optimization (ICO) algorithm dynamically adjusts input current to maximize efficiency while avoiding adapter overload. The integrated DC/DC converter minimizes voltage conversion losses, achieving up to 92% efficiency under typical operating conditions.

Advanced thermal regulation plays a crucial role in maintaining efficiency across temperature ranges. The charger ICs automatically reduce charging current by 10% for every 5°C increase above 85°C junction temperature, preventing performance degradation. Engineers have reported 18% faster charge cycles compared to linear charging solutions in 25°C ambient conditions, with even greater advantages in high-temperature environments.

What Safety Mechanisms Are Integrated into These Charger ICs?

Both ICs include 14 safety protections: battery over-voltage, input over-voltage, thermal shutdown, and watchdog timer monitoring. The BQ25629 adds a dedicated PROCHOT output for CPU throttling during overheating. Real-time monitoring of battery temperature via NTC input ensures safe charging across environmental conditions.

The redundant voltage monitoring system performs 100,000 checks per second across all power domains. A unique battery authentication feature prevents charging of non-certified cells through SHA-1 cryptographic verification. Safety timers with ±10% accuracy ensure automatic termination of faulty charge cycles, while the integrated reverse current blocking protects against battery discharge through the input port.

Which Applications Benefit Most from These Charger Solutions?

Ideal for space-constrained devices: smartphones, tablets, drones, and medical wearables. The BQ25628’s 2.5mm x 2.5mm WCSP package suits ultra-compact designs, while the BQ25629’s additional PROCHOT feature targets high-performance computing devices requiring active thermal coordination with host processors.

How Does Programmable Thermal Management Optimize Performance?

Users can configure junction temperature limits through I²C interface, balancing charging speed with thermal constraints. The adaptive charging algorithm reduces current when temperatures approach critical thresholds. The BQ25629’s PROCHOT signal enables system-level thermal management by triggering CPU performance reduction during excessive heat buildup.

What Design Considerations Ensure Optimal Charger Implementation?

Critical factors include PCB layout optimization for thermal dissipation, proper decoupling capacitor placement, and NTC thermistor selection. Designers must configure charge parameters (voltage/current thresholds) through I²C and implement firmware for dynamic power path management. TI’s EVM (BQ25628EVM-725) provides reference designs for various input sources and battery configurations.

Can These ICs Support Wireless Charging Integration?

Yes, both support wireless charging when paired with TI’s wireless power receiver ICs (e.g., BQ51003). The charger ICs handle battery management while the wireless receiver manages power reception. Designers must account for efficiency losses in wireless systems by adjusting input current limits and thermal budgets accordingly.

What Are the Key Differences Between BQ25628 and BQ25629?

Feature	BQ25628	BQ25629
PROCHOT Output	No	Yes
Package Size	2.5×2.5mm	3.0×3.0mm
Typical Application	Consumer Wearables	High-Performance Tablets

Expert Views

“The BQ2562x series represents a paradigm shift in compact charging solutions. By integrating the power path management and thermal regulation typically requiring discrete components, TI enables 30% smaller PCB footprints compared to previous generations. The ICO algorithm’s ability to prevent adapter collapse during simultaneous charging and system loading is particularly valuable for always-on devices.” – Senior Power Systems Engineer, Tier-1 Consumer Electronics OEM

Conclusion

The BQ25628 and BQ25629 set new benchmarks for intelligent battery management in portable electronics. Their combination of high efficiency, advanced safety features, and programmable thermal management addresses critical challenges in modern device design. Engineers should carefully evaluate thermal requirements and system integration needs when selecting between these two closely related IC variants.

FAQ

What Is the Maximum Input Voltage Supported?

Both ICs support 3.9V to 13.4V input range, with 20V absolute maximum rating. The wide input voltage enables compatibility with USB-PD, QC3.0, and traditional 5V/9V/12V adapters.

How Does Ship Mode Extend Shelf Life?

Ship mode reduces battery drain to 2μA, preserving charge during storage. Activated via I²C command, it disconnects the battery from system loads while maintaining protection circuit functionality.

Can These ICs Charge While Powering the System?

Yes, the integrated power path management supports simultaneous charging and system operation. The IC prioritizes system power from input source, supplementing with battery power when input current is insufficient.