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Original question:

BQ24165 need confirmation

BQ25125: Load Sharing Circuit for Low-Power Embedded Project

Yong Hui Liew
Prodigy 40 points
Part Number: BQ25125
Other Parts Discussed in Thread: BQ25570, BQ25505, BQ25504

Hi, I am trying to develop a low-power embedded system running mainly on a rechargeable 3.7 V Lithium Ion battery and a secondary energy harvesting circuit (low energy) to charge the battery simultaneously. 

I am thinking of a load-sharing circuit (battery charger with the power-path management system) that also has an integrated LDO/Buck-Boost circuit to supply a constant 2.5-3.3V load of up to 500mA.

My system will be in sleep mode most of the time and will use the most current only (up to 150mA) during RF transmissions. 

Are there any products that can meet these requirements? I am pretty new to Battery Management System (BMS) design, so will appreciate all the help I can get for my project. 

Thanks!


  • 0
    TI__Genius 13435 points

    Hello,

    We offer a couple chargers that can help match your system needs.

    The BQ2512x family of devices offers chargers with integrated Buck-converters that can provide the required load current. They also integrate a Load Switch / LDO rail that provides additional power to your system.

    The BQ2515x family of devices offers similar charging capabilities with only an integrated LDO rail that can support loads up to 150 mA.

    In terms of energy harvesting, we offer the BQ25504, BQ25505, and BQ25570, the last of which includes an integrated boost charger as well.

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    Prodigy 40 points

    Hello Juan, 

    From the energy harvesting chargers, it seems like the BQ25570 offers output load current up to 100mA only. Would the BQ2512x be suitable for use with energy harvesting instead?  

  • 0 in reply to Yong Hui Liew
    TI__Genius 13435 points

    Hello,

    With regards to energy harvesting, this is dependent on the input source to your application. The BQ25570 provides the benefit of a boost converter so that a battery can be charged even with a low VIN. If you are expecting an input voltage that is higher than your battery voltage then the BQ2512x can work for your application.

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    Prodigy 40 points

    Thanks for the reply. I'll be using piezoelectric energy actually, so I'm guessing it'll be in the millivolt range? So I will need the BQ25570 for the low VIN charging. However, my application also includes an RF module. That alone uses 150mA during transmission. 

    Would it be possible for the battery to take over and supply the high current in this case? 


  • +1 in reply to Yong Hui Liew
    TI__Genius 13435 points

    Hello,

    During short-high current events the battery could take over to provide the high current required. It's important to keep in mind the BQ25570 can harvest energy from VIN as low as 100 mV but can require 600 to 700 mV OC input voltage for cold start.

    Best Regards,

    Juan Ospina