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BQ24703: Can this part charge efficiently at a low charging current (500mA - 2A) and are their newer recommendations for external components (ones on the datasheet are obsolete)?

Lauren Mayfield
Expert 7905 points
Part Number: BQ24703
Other Parts Discussed in Thread: BQ25792, BQ24610

Hi team,

I had some questions on this part on behalf of my customer.

1. How efficiently can this part charge at a low charging current? Like down to 500mA and up to around 2A? I noticed the ripple will be effected but by how much? We have also been looking at the 24702 with the lower charging current but this part is slightly cheaper.

2. Is there an EVM that comes with this part? I didn't see any on the product page, just a user guide.

3. Are there newer recommendations for FETs/external components on the application schematic? The ones on there right now appear to be obsolete.

Thanks,

Lauren

  • 0
    TI__Genius 11850 points

    Hi Lauren,

     

    The BQ24703 is a legacy device that is 18 years old, and EVMs are no longer available. Since the BQ24703 is an asynchronous buck charger, the low side switch is a diode, which reduces the efficiency. I strongly recommend one of our newer chargers instead, which can provide higher efficiency, a simpler BOM without so many external diodes, and more features. If you let me know your requirements, then I can help suggest another charger which may be a better fit for your application. Please provide the information below:

    • Adapter voltage
    • Battery cell count
    • Battery charge current
    • Is a standalone charger or a host-controlled charger preferred?

    Best regards,

    Angelo

  • 0 in reply to Angelo Zhang87
    TI__Expert 7905 points

    Hey Angelo,

    I saw it was pretty old, it was the only part I found with most of the specs they need. If you have a newer recommendation that would be even better.

    charge current 1.5A-2A max, closer to 1A under normal circumstances, he also mentioned 500mA-750mA potential charge current on the phone.

    • High availability, low lead times
    • Operating Temperature -40 to 85C
    • Support Lithium Polymer/Lithium Ion chemistry at a minimum
    • Ability to charge while Processor is Off (meaning can automatically know when sys power is present and can switch to the battery power to charge without instructions from the processor)
    • 2-4 Cell support preferred
    • Small footprint
    • Low Cost
    • Prefer ability to seamlessly switch between system power and battery power
    • Charging/status LED preferrable
  • 0 in reply to Lauren Mayfield
    TI__Genius 11850 points

    Hi Lauren,

     

    Based on those requirements, please take a look at the BQ24610 and the BQ25792. The BQ24610 is a standalone buck charger, while the BQ25792 is an I2C-controlled buck-boost charger. They should both be a better fit compared to the BQ24703.

     

    Best regards,

    Angelo

  • 0 in reply to Angelo Zhang87
    TI__Expert 7905 points

    Hey Angelo,

    Both look good assuming they are readily available. I noticed they have a 10A and 5A charge current respectively. Can you confirm they will still charge efficiently at <2A?

  • 0 in reply to Lauren Mayfield
    TI__Genius 11850 points

    Hi Lauren,

     

    Please refer to Figure 12 in the BQ24610 datasheet and Section 8.7 in the BQ25792 datasheet. There are several graphs showing the efficiency vs. charge current under various operating conditions. Generally, the efficiency is higher at 2A compared to higher currents (>5A).

     

    Best regards,

    Angelo