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TPS2663: Current Limiting for Battery Charging

Tunc Ozdemir
Prodigy 20 points
Part Number: TPS2663

Hello,

I am trying to control my battery charger with the TPS26631 Current Limiter. I have a 3A charger powering the current limiter. Normally you would not expect more than 3A from such charger, however since there are large capacitors at the end of its internal circuit, charger is capable of providing higher inrush currents. To account for all this information I have set the current limit to 4.2A. If I did not set it high enough the current limit was exceeded and IC went into fault mode. However recently I had to change the battery I was charging with a bigger one. In this case I can charge the battery connected directly to the current limiter, but when the battery is in low power mode (0V, power cut from internal BMS) and connected to the load circuit the inrush current is much higher and it exceeds the 4.2A x2.

I don't want to change my current limit for different batteries. What should be my approach? Is this current limiter not suitable for battery charging applications.

  • 0
    TI__Guru** 105361 points

    Hi Tunc,

    Welcome to E2E!

    Do you want current limiter of higher power rating ? Inrush current can be handled with TPS26631 in dvdt mode 

    Can you please share the block diagram of your system showing battery charger, battery, large capacitor, current limiter, internal BMS connections to understand better.

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    Prodigy 20 points

    Currently, I have placed a 1uf capacitor to the dvdt pin. I have tried with no capacitor, 100nF, 220nF and 1uF. On every single one the device went into the Thermal shutdown after 2.5s. I am reading the IMON pin to see the current going through the device. 

    IC Setup: https://prnt.sc/1w2xvp0

    Basic Block Diagram: https://prnt.sc/1w2yzlk

    Before experimenting with the dvdt mode my setup was a little different. When the IC first started working it was connected to a dummy load of 1K8 Ohms. Then after 3s I switched a relay to connect to the main battery. However in this scenario the dvdt was not used. When I made the relay always open, the dummy load is eliminated from the circuit and the battery is connected directly. However at the startup IC heats up and wents in to Thermal shutdown. Is there something I need to change on the schematic or is this current limiter not compatible for battery charging control.

    The Setup where I could get the IC working without Thermal shutdown: https://prnt.sc/1w2zmi6

  • 0 in reply to Tunc Ozdemir
    TI__Guru** 105361 points

    Hi Tunc,

    I am not able to open those images. Can you share them as attachments 

    Best regards, Rakesh 

  • 0 in reply to Rakesh
    Prodigy 20 points

    IC Setup:

    Basic Block Diagram:

    The setup where I could get the IC working without Thermal Shutdown:

    Here you go, sorry for the inconvenience. 

  • +1 in reply to Tunc Ozdemir
    TI__Guru** 105361 points

    Thanks 

    Battery charging needs extended period of current limit mode of operation. This device only supports 2.5s interval. We don't have solution for your requirements.

    You may need to use cv/cc based charger.

    Best regards, Rakesh