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BQ24079QW-Q1: Rds of the MOSFET used for supply line and charger line

Part Number: BQ24079QW-Q1

Hello,

we are using BQ24079-Q1 for charger. Our application require 1.4A continuous current from input to output  supply. 

datasheet shows 1.5A max. Can it be used for 1.4A. what will be the temperature rise?

Please provide the Rds on of IC.

Regards,

Sudharshana

  • Hi Sudharshana,

    datasheet shows 1.5A max. Can it be used for 1.4A. what will be the temperature rise?

    Yes, the device can be used for 1.4 A. This is within the range specified for the recommended operating condition for the input current that is provided in Section 8.3 Recommended Operating conditions. Do note that if you have anything about 100 mA of charge current, regulation loops may come into play such as DPPM. 

    what will be the temperature rise?

    If you know current draw at the OUT pin and the charge current pin, you can calculate the power dissipation and approximate the temperature rise using the RθJA value that is listed in the datasheet. This is 43.2 C / W. 

    Please provide the Rds on of IC.

    RDS_ON for both FETs can be calculated using the specified drop out voltages in the POWER PATH section of the Electrical Characteristics table. These voltages are both measured with a current of 1 A. So the RDS_ON of the input FET is 300 mOhm typically and the batterey FET has an RDS_ON of about 50 mOhm. 

    Best Regards,

    Anthony Pham