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TPS2595: charging current issue

swe zin
Prodigy 20 points
Part Number: TPS2595
Other Parts Discussed in Thread: TPS25940

Hi

We used TPS2595 for charging super capacitor 15 F. Our application is the same as http://www.ti.com/lit/an/slva920/slva920.pdf. We need at least 1.2 A to charge the super capacitor , But we can get only 400 mA as a charging current.TPS2595-12.13.docx

  • 0
    TI__Guru 57737 points

    Hi Swe Zin,

    Thanks for reaching out to us. Below are my comments,

    • TPS2595 does not have Reverse Current blocking capability as there is no blocking FET in the IC. The body diode of the internal FET starts conducting and there will be current flow from Super cap to Input once the input voltage drops below super cap voltage. So, we recommend you to afead with TPS25940 which has a blocking FET.
    • You can increase the charging current by appropriately selecting the dv/dt capacitor. What is the current dv/dt cap in the circuit ? It is not clear But, as mentioned in the app note, increasing the charging current increases the power dissipation across the internal Mosfet and once it reaches the Thermal Limit, the device shuts down. So, we recommend that you follow the procedure mentioned in Figure 7 of the app note.

  • 0 in reply to Praveen GD
    Prodigy 20 points

    Hi Praveen

    Thanks for the fast response . We have solved the problem after adding the diode in between the source and charging circuit and we used the voltage sense as in attached doc. Now the charging current is 1.2 A and work properly. By the way  we use TPS 259533TPS259533.docx

    Thank you 

    Best Regards

    Swe Zin