The BQ40Z50RSMR - R1 is an advanced battery management chip launched by Texas Instruments (TI), 

designed specifically for 1 - 4 - cell lithium - ion/polymer battery packs.It is a battery pack-based fully integrated single chip solution, 

providing a variety of functions such as power monitoring, protection and certification for 1, 2, 3 and 4 series lithium-ion or lithium polymer battery packs.

 Its functions and applications are as follows:

Functions
Accurate Power Monitoring: It adopts the patented Impedance Track™ technology to accurately measure the available power in lithium - ion and lithium - polymer batteries. 

Using integrated high - performance analog peripherals, it can measure the available capacity, 

voltage, current, temperature, and other key parameters of the battery, retain accurate data records, 

and report this information to the system host controller through the SMBus v1.1 compatible interface.
Integrated Protection Features: 

It provides software - based level 1 and level 2 safety protection to prevent over - voltage, under - voltage, over - current, short - circuit, overload, 

over - heat, and other battery pack and battery - related faults. It also has a high - side N - channel protection field - effect transistor (FET) drive.
Cell Balancing: It supports integrated cell balancing during charging or standby, which helps to improve the overall performance and service life of the battery pack.

Programmable Protection Thresholds and Delays: It has a complete array of programmable protection features, 

including voltage, current, temperature, charge timeout, etc., which can be set according to specific application requirements.
Battery Life Prediction and Health Monitoring: It can monitor the state of health (SOH) of the battery and predict the battery life, 

providing users with relevant information about the battery's health status.
Support for Turbo Boost Mode: It can provide the maximum power and current to the host system, supporting Turbo boost mode, 

which is beneficial for applications that require short - term high - power output.
Battery Trip Point (BTP) Support: It supports the battery trip point, and can send a BTP interrupt signal to the host 

system at the preset charging threshold state, so that the system can take corresponding actions in time.
SHA - 1 Authentication: With the secure memory for authentication keys, SHA - 1 authentication can identify genuine battery packs, 

which helps to prevent the use of counterfeit batteries and improve system security.
Built - in Temperature Sensor and External Temperature Detection: It has a built - in temperature sensor and can also detect external temperature, 

which can more comprehensively monitor the battery temperature and ensure the safe operation of the battery.
LED Display: It supports LED display, which can visually display the battery status, such as remaining power, charging status, etc.

Applications

Electric Vehicles: It is suitable for battery management systems in electric vehicles, which can accurately monitor the power and status of the battery pack, 
ensure the safe and efficient operation of the battery, and improve the endurance and performance of electric vehicles.
Portable Devices: Such as laptops, tablets, smart phones, and other portable electronic devices.
 It can effectively manage the battery in the device, improve battery life, and ensure the normal operation of the device. 
At the same time, its compact package is also suitable for the miniaturization requirements of portable devices. Smart Bracelets: Precision Energy Monitoring
In a smart fitness tracker, the BQ40Z50RSMR-R1 is integrated to manage a single-cell Li-ion battery. 

Leveraging its Impedance Track™ technology, the device provides real-time, 

sub-1% accuracy in remaining capacity (mAh) and state of charge (SoC) measurements . 

For example:Real-Time Data Transmission: The chip communicates with the tracker's MCU via the SMBus v1.1 interface, 

delivering critical parameters like voltage, current, and temperature. 

This enables the device to dynamically adjust power consumption-e.g., 

triggering low-power mode when SoC drops below 10% .
Safety-Centric Design: Built-in overvoltage/undervoltage protection 

and high-side N-channel FET drive prevent battery damage during extreme usage, 

ensuring the tracker operates safely even during intensive workouts .
Smartwatches: Enhanced Safety and Longevity
A premium smartwatch utilizes the BQ40Z50RSMR-R1 to safeguard its multi-cell Li-polymer battery pack.

 Key applications include:Comprehensive Protection: 

The chip's dual-level safety mechanisms (Level 1 and Level 2) guard against overcurrent, 

short circuits, and thermal runaway. For instance, if the watch's GPS module draws excessive current, 

the BQ40Z50RSMR-R1 immediately disconnects the load via its programmable OCC (Overcurrent Charge/Discharge) thresholds .
Cell Balancing: During charging, the integrated cell balancing feature equalizes cell voltages, 

extending the battery pack's cycle life by up to 20%. 

This is critical for smartwatches that require consistent performance over years .
Turbo Boost Support: When the watch enters high-performance modes (e.g., 4G connectivity or GPS navigation), 

the BQ40Z50RSMR-R1 enables Turbo Boost to deliver peak current, ensuring seamless operation without voltage droop .
 AR/VR Headsets: High-Power, Low-Delay Management
In augmented reality (AR) glasses, the BQ40Z50RSMR-R1 manages a 3-cell Li-ion battery pack under demanding conditions:
Dynamic Power Allocation: The chip's adaptive charging algorithm optimizes power delivery during mixed workloads 

(e.g., rendering 3D graphics while streaming data). It adjusts charge current in real time to prevent thermal throttling, 

maintaining stable operation even during prolonged use .
Battery Health Monitoring: Using SHA-1 authentication, the BQ40Z50RSMR-R1 verifies the authenticity of the battery pack, 

preventing counterfeit cells that could compromise safety. Additionally, its state of health (SOH) tracking alerts users when battery degradation exceeds 20%, 

ensuring timely replacements .
Temperature Resilience: With a -40°C to 85°C operating range, the chip reliably monitors battery temperature in extreme environments 

(e.g., outdoor AR navigation in hot climates), activating overtemperature protection to avoid performance degradation .
Wireless Earbuds: Miniaturized, Efficient Power
For true wireless earbuds, the BQ40Z50RSMR-R1's compact 32-pin VQFN package (4x4 mm) enables space-constrained designs while offering robust features:
Ultra-Low Power Modes: The chip enters standby mode with <1 μA current consumption when the earbuds are not in use, 

preserving battery life during storage. Its wake-on-charge feature automatically resumes monitoring when the charging case is connected .
LED Indication: Integrated LED drivers provide  battery status feedback on the charging case 

(e.g., green for 75–100% SoC, red for <20% SoC), enhancing user experience .
Fast Charging Optimization: The BQ40Z50RSMR-R1 supports JEITA-compliant charging profiles, 

ensuring safe fast charging (e.g., 10-minute charge for 1 hour of playback) without compromising battery longevity

Precautions for Using Battery Fuel Gauge BQ40Z50-R1:

1. The /PRES pin is used to detect whether there is a system. When this pin is pulled down externally, it means that there is a system. 

2. /SHUTDN pin is used to control the chip's sleep or operation. The falling edge is valid. 

     Entering sleep and wake-up are triggered by falling edges. You can use button control. 

3. The /PRES pin and the /SHUTDN pin are the same pin. 

4. When the application is less than four strings, start from the highest battery-saving cell (VC4). 

5. The maximum internal equalization current is 10mA, which can equalize multiple sections at the same time; 

    the external equalization circuit can only equalize one section at the same time. 

6. The pressure difference range between the current detection input SRP and SRN is -0.1V ~ 0.1V. 

7. When V(SRP) > V(SRN), it is charging, otherwise it is discharge. 

8. It has historical data recording function, and records specific data every 10 hours: maximum and minimum battery voltage, 

    maximum battery voltage difference, maximum charging current, maximum discharge current, 

    maximum average discharge current, maximum average discharge power, maximum minimum battery temperature, 

   maximum battery temperature difference, maximum internal sensor temperature, maximum MOSFET temperature, 

   safety time occurrence and cycles in the last safety event, effective charging planting and cycles in the last cycle, 

  Qmax and Ra update times and cycles in the last update, Shutdown times, equalization time per battery cell, 

  total running time and running time in each temperature range. 

9. Support SHA-1 certification. 

10. It can drive 3, 4 and 5 segment LEDs to display capacity status and fault code indication. 

11. The battery voltage detection period is 250ms. 

12. The recommended resistance value of the current sense resistor is 1mΩ ~ 3mΩ. 

13. With an internal temperature sensor and four external temperature sensors, 

    all five sensors can be individually configured to turn on or off and can be configured for cell temperature or FET temperature detection. 

14. The communication method is SMBus V1.1. When the two communication lines are pulled down for more than 2S, 

    the communication is closed. After the two lines are pulled up, the communication will resume work within 1ms. 

15. It has three working modes: normal mode, sleep mode, and Shutdown mode. 

16. Normal mode: Data sampling, calculation, protection action execution and data update are performed in 250ms cycles, 

     and the time interval is a low power consumption stage. 

17. Sleep mode: Data sampling, calculation, protection action execution and data update are performed with adjustable time periods, 

     and the time interval is a low power consumption stage. When a current is detected or a fault occurs, 

it can be woken up to normal mode. 

18. Shutdown mode: All are prohibited. 

19. The protection parameters are configured using the bqSTUDIO tool. 

20. If the number of application strings is 1 string or 2 strings, 

     the first parameter configuration should be connected to an external charger or power supply to prevent the chip from being turned off. 

      (Because the chip default application is 3 strings, the total voltage of 1 string or 2 strings is too low, causing the system to shut down.)

21. Charging and discharging MOS is NMOS and has high-end drivers. The pre-charged MOS is PMOS. 

22. The FUSE pin outputs an effective signal of 8V. In the event of a safety fault, it is used to drive the MOS to turn on to fuse the three-terminal fuse. 

23. The equivalent resistance of the internal equalization circuit is 200Ω, 

      and it is recommended to have an external input resistor of 100Ω-1kΩ for effective cell equalization. 

24. A diode is used between the VBAT pin and the battery to prevent the voltage drop caused by a short circuit from affecting the VBAT voltage. 

25. Connect a MOS tube (Q4) in parallel to the GS end of the discharge MOS to prevent the charger from being reversed. 

26. The BQ40Z50 has four external thermistor interfaces, each of which can enable an internal pull-up resistor of 18KΩ. Unused interface grounding. 

27. Three LED drive pins can control up to five LEDs without the need for external driving voltage. 

      Unused LED control pins can be hung or grounded. If the LED function is not used, the DISP pin needs to be grounded. 

28. The safe PTC thermistor interface can be connected to an external PTC resistor to detect the MOSFET temperature. 

      The driving current of the PTC pin is 370nA. The PTC fault is triggered when the pin voltage is higher than 0.7V. 

      This fault is a safety fault and will drive the FUSE pin to output an 8V voltage and can only be cleared by the reset operation. 

       The effect of preventing MOS overheating can be achieved by selecting appropriate PTC. When this function is not used, 

      the PTC pin must be grounded through a 10KΩ resistor.

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