ADP5065 Minimum Input Charging Voltage

ADP5065 datasheet advertises "Operating input voltage from 4.0 V up to 5.5 V " but it only starts charging the battery after VIN > 4.85V. Even when we have set:

Fast charge current programming bus 550mA (the minimum)

Termination voltage programming bus 4.2V

VINx pin input current-limit programming bus  500 mA

System Consumption is only about 60mA

  • +1
    •  Analog Employees 
    on May 8, 2020 5:10 PM

    Hello,

    The 4.0V-5.5V encompasses all operation settings. Not all setups will be able to charge in the full range. Clearly in your case 4.0V could not work as the ADP5065 can only step down VIN.

    Some headroom is required between the VIN voltage and the battery voltage. This requirement will increase depending on the charge current. Lowering the charge current may allow you to charge at a slightly lower input voltage. Even better, if you can keep your VIN at 5V, you can meet your 550mA charge current requirement.

    To give you an idea: on my setup, charging at just 100mA, the ADP5065 is able to charge up to 4.2V with as low as 4.65V VIN.

    Regards,

    Zack

  • Thank you for your replay.

    To meet UL’s 6007911 intrinsically safe certification, we need to include 3 blocking diodes in between the USB connector and the ADP5065 VIN pin. So we only have around ~ 4.35 V at VIN. The required headroom  is understandable but we didn't see a VIN/Charging Current/Termination Voltage relationship chart in the datasheet, It doesn't even work by selecting a charging current as low as 32mA on our setup.

    But you are right, thank you for your answer.