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BQ25600D: Switching efficiency & VBUS current

user4328740
Prodigy 30 points
Part Number: BQ25600D

Hi

We have contacted you to confirm the specifications of the Charger IC "BQ25600D". Please kindly answer the following questions.

1. About switching efficiency

Regarding the efficiency of the charging IC, we have confirmed the specifications below.

image.png

We set 960mA charging, could you provide us with numerical values ​​for min, typ, and max values ​​for efficiency in that case?

If you need the calculation and the conditions, please let us know.


2. About VBUS current

It is related to the first check item.
Is it possible to calculate the min/max VBUS current below following conditions in order to confirm?

 - VBUS voltage range: 4.8V to 5.2V
 - VBAT voltage range: 3.7V to 4.0V
 - Charging current: 960mA
 - SYS side: No load assumption (about 30uA)

If you need additional conditions, please let us know.

We apologize for the inconvenience, and thank you for your cooperation.

Best Regards,
FUKUYA

  • 0
    TI__Expert 5590 points

    Hi FUKUYA:

    What is the inductor you use? Inductor DCR and size? Efficiency is inductor dependent.  

    Regards,

    Hong

  • 0 in reply to Hong Mao
    Prodigy 30 points

    Hi Hong,

    We use metalcore-inductor "MAKK2520T1R0M" made by Taiyo Yuden.

    DCR is typ 0.06Ω, max 0.072Ω.

    Size is 2.5*2.0, tolerance ±0.2, height 1.0mm max.

    Best regards,

    FUKUYA

  • 0 in reply to user4328740
    TI__Expert 5590 points

    Hi FUKUYA:

    Here is the estimation:

    Case 1

    VBUS = 5.2V, VBAT = 3.7V, ICHG=0.96A, efficiency 92.7%, IVBUS_MIN =  0.737A

    Case 2

    VBUS = 4.8V, VBAT = 4, ICHG=0.96A, efficiency 93%, IVBUS_MAX=  0.86A

    Again, this is just estimation.

  • 0 in reply to Hong Mao
    Prodigy 30 points

    Hi Hong,

    Thank you for your estimation. I understand your calculation is estimation.

    I have additional questions.
    Is the calculated efficiency the typical value?
    Do you have min and max specifications for efficiency?
    I would like to confirm the dependency of IVBUS due to efficiency variations.

    Best regards,

    FUKUYA

  • 0 in reply to user4328740
    TI__Expert 5590 points

    Hi Fukuya:

    Please see my response below:

    Is the calculated efficiency the typical value?

    Case 1:

    VBUS = 5.2V, VBAT = 3.7V, ICHG=0.96A, efficiency 92.7%, IVBUS_MIN =  0.737A

    The efficiency I estimated is the best efficiency. The best efficiency is 92.7%, typical is 92.2% and worst is 91.8%.

    Case 2

    VBUS = 4.8V, VBAT = 4, ICHG=0.96A, efficiency 93%, IVBUS_MAX=  0.86A

    The efficiency I estimated is typical efficiency. The best efficiency is 93.4%, typical is 93% and worst is 92.6%.

    I would like to confirm the dependency of IVBUS due to efficiency variations.

    IVBUS depends on efficiency as well as VBUS. It depends on VBUS more than efficiency if the output power is constant.