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BQ24075: BQ24075 output votlage/current with VIN and VBAT supply

Bhavesh Bhadricha
Prodigy 90 points
Part Number: BQ24075

in my application Vin =Vusb=5V for charging battery (1cell,4.2V,1000mAh)
in case of deep discharge or low battery voltage the system should run in Vbus supply

is Vout 5.5V and Iout=4.5A available in below scenarios as per datasheet 


1)wtih VIn=5.V, Vbat=0V (no battery) what would be the continuous Vout and Iout
2)wtih VIn=5.V, Vbat=2.5V (deep discharged battery) what would be the continuous Vout and Iout
3)wtih VIn=0.V, Vbat=4.2V (ful charge battery) what would be the continuous Vout and Iout

4)wtih VIn=5.V, Vbat=4.2V (ful charge battery) what would be the continuous Vout and Iout

  • 0
    TI__Intellectual 910 points

    Hello Bhavesh,

    Thanks for reaching out on E2E. This is a very good question.

    Please keep in mind to get 4.5A at I_out then there are a few things that must be met. First, the IC needs to be in DPPM mode. Where the sum of the charging and system load current exceeds the maximum input current. When V_out falls to V_dppm the IC then enters DPPM, the charging current is reduced as the I_out current increases in order to maintain the system output. While in DPPM if the charging current falls to zero, and the system load increases beyond the programmed input current limit, V_out will reduce further. When V_out drops below the V_BSUP1 the battery then begins to supplement the system load. You will essentially have P_in + P_bat going to P_out. 

    V/R

    Rafael Camarillo

  • 0 in reply to Rafael Camarillo
    Prodigy 90 points

    Dear Rafael,
    I understand the 4.5A current is sum of input supply current and battery discharging current. 
    I am not able to find  V_BSUP1 in datasheet?

    In our application requirement,

    Vin would be 5V/1A and battery is 4.2V/1000mAh.

    1)the battery charger shall power the system while simultaneously and independently charging the battery.


    2)Vin  should not drop if the battery is deep discharged or absent or defective

    3)the battery charger shall be able to charge deep discharge battery

    4)when Vin =5V/500mA is connected to the battery charger , with deep discharged battery, the charge IC should able to charge the battery as well as provide the inrush current from the battery to turn on the system

    does BQ24075 suffice my above  4 requirement or you can suggest suitable part
    note: at the OUT of the battery charger we have boost converter to provide 5V/4A to the entire system

  • 0 in reply to Bhavesh Bhadricha
    TI__Intellectual 910 points

    Hello Bhavesh,

    Just a few points...

    1)the battery charger shall power the system while simultaneously and independently charging the battery.

    This is true as long as the P_IN is enough to supply P_SYS and P_BAT. (ie. If I_SYS is ~600mA then I_BAT will be ~400mA)

    2)Vin  should not drop if the battery is deep discharged or absent or defective

    This is true as long as long as the load on SYS does not exceed the Input current.

    3)the battery charger shall be able to charge deep discharge battery

    This is true.

    4)when Vin =5V/500mA is connected to the battery charger , with deep discharged battery, the charge IC should able to charge the battery as well as provide the inrush current from the battery to turn on the system

    The IC should be able to charge the battery and provide current to the system. The battery would not be doing anything at this point. 

    V/R

    Rafael Camarillo