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BQ24800: supercap management

Alessandro Cogliati
Prodigy 20 points
Part Number: BQ24800
Other Parts Discussed in Thread: BQ25756

Dear all,

Would it be possible to use BQ24800 to replace LTC3350 for supercap management?

Here you can find more details about the application we are interested to:

  • input voltage: 12V
  • Supercap configuration: 4 supercap of 2.5V in series (10V in total)
  • Desidered functionality: 
    • Superdiode configuration to provide the 12V of the input to the system
    • Buck mode to charge the supercap 
    • Boost mode to provide the 12V to the system, taking the energy from supercap, in the condition of absence of 12V as input
    • It would be nice if the IC (BQ24800) is able to handle the change of the operating mode standalone (without having to set the buck/boost mode through the I2C interface)
    • It is ok to configure the BQ24800 internal parameters (such as the battery overvoltage) through the I2C interface (in LTC3350 everything is configurable through resistances)

 

In case you think BQ24800 is not the right IC for this application, can you suggest a different IC to perform the desidered functionality

Let me know if you need further information

Best regards

Alessandro

  • 0
    TI__Mastermind 29882 points

    Hello Alessandro, 

    Thank you for reaching out!

    I will look into this and get back to you by Friday with product recommendations. 

    Best Regards, 

    Aya Khedr 

  • 0 in reply to Aya Khedr
    TI__Mastermind 29882 points

    Hi Alessandro, 

    The BQ24800 does not support supercapacitor charging.

    We highly recommend the BQ25756 for your application. It is a stand-alone or I2C controlled bidirectional buck-boost charge controller. It has a smaller footprint than the LTC3350 and can provide twice as much charge current. 

    • In order for the BQ25756 to enter supercapacitor mode, you would need  to disable the pre-charge bit with I2C. The BQ25756 will be able to boost the supercaps until they reach 3.5V. 
    • The charge current and charge voltages can be set with resistor values, and the device would know when to do buck/boost mode automatically. 
    • Here is the product page for the Evaluation Module: www.ti.com/.../BQ25756EVM

    Please let me know if you have additional questions!

    Best Regards, 

    Aya Khedr