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BQ25890: Efficiency at lower VBAT

Atsushi Hirai
Expert 4920 points
Part Number: BQ25890

Hi team,

The VBAT voltage of Datasheet Figure 8-1 is 3.8V but, customer want to know the efficiency at VBAT = 2.8V, 3.3V or so.

Could you provide it or, measure it if the evaluation data is not exist?

Best Regards,

  • 0
    TI__Mastermind 31410 points

    Hi Atsushi, 

    We can help to take some efficiency measurements at at the lower battery voltages requested. Can you help to provide more specific test conditions the customer is interested in. 

    Specifically what VBUS voltage are they planning to operate with? What precharge current (for 2.8V test) and fast charge current do they want to know the efficiency for? 

    Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    TI__Expert 4920 points

    Garrett-san,

    Thanks.

    Their VBUS voltage is 5V. It's okay that the other conditions are same as Figure 8-1.

    Please provide efficiency plot.

    Best Regards,

  • 0 in reply to Atsushi Hirai
    TI__Mastermind 31410 points

    Hi Atsushi, 

    We do not currently have the resources available to test all conditions same as Figure 8-1 in the datasheet. If the customer does not have any specific current range they are interested in I can provide efficiency results with VBUS = 5V, VBAT = 3.3V and ICHG from 500mA to 3A with a 500mA step size. 

    For VBAT = 2.8V I can provide efficiency results for IPRECHG approx. = 100mA, 500mA, 1A. 

    I will provide the results in this thread before the end of the week. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    TI__Expert 4920 points

    Garrett-san,

    Thanks. It's acceptable.

    I'll wait the measurement result.

    Thanks,

  • +1 in reply to Atsushi Hirai
    TI__Mastermind 31410 points

    Hi Atsushi, 

    I have provided the requested efficiency results below. Please be advised that the efficiency will worsen depending on the SYSMIN setting because when VBAT < V_SYSMIN there is additional power lose at Q4 BATFET acting as an LDO. 

    For the below results I have set SYSMIN = 3.0V 

    -VBAT = 3.3V

    -VBAT = 2.8V 

    Best Regards,

    Garrett