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TPS54231 Power Handling Capability

J D
Prodigy 100 points
Other Parts Discussed in Thread: TPS54231, TPS54620, BQ2031, BQ24450

Dear All,

I wish to use TPS54231(Buck converter) to charge a 6V/10Ah  battery in one of my applications.The data sheet says it has a output current capability of 2A .So does it have an internal current limit circuitry that would protect it from over supplying a current beyond safe limits to say a fully discharged battery?

I have assembled a small circuit and my observation is it does support a current beyond 2A but at the same time it gets pretty hot as well.So is this operation sustainable?

Specs are: Vin :8V,  Vout:7V, Output load: Battery.

  • 0
    TI__Guru**** 150610 points

    The TPS54231 does have an internal current limit that will limit the peak current to 3.5A typical.  This value is the load current plus 1/2 of the inductor current ripple.  At the high duty cycle, going from 8V to 7V, the IC will get very hot.  If you only need 8V in, please look at the TPS54620, which can support 6A output current.

    You will need a dedicated battery charger after the buck converter to safely charge your battery.  Which one are you using?  How much current are you charging your battery with?  What chemistry do you have?

  • 0 in reply to Chris Glaser
    Prodigy 100 points

    Hi Chris,

    Thanks for your prompt reply.I shall look into TPS54620.I am charging my battery with 2A current. Its a lead acid battery of 6V/10AH.

    I was just wondering if I could use this chip (TPS54231) for one of my other applications where I required a CV/CC kind of functionality from this chip.As in once the load current reaches the CC limit (which would preferably be 2A in this case), my output voltage would drop but the output current won't exceed beyond 2A even if load resistance is reduced further.

    is this possible? How?

     

  • 0 in reply to J D
    TI__Guru**** 191445 points

    Yes that is how peak current limit works.  The on time of the high side switch is terminated as soon as the peak switch current reaches the current limit.  as teh load is increased above this point the voltage at the output is reduced.  the currnet limit for the TPS54231 is 2.3 A minimum but may be as high as 4.5 A or so.

  • 0 in reply to J D
    TI__Guru**** 150610 points

    You would need to get approval from your battery pack manufacturer that your suggested method of charging isok to them and safe.  The issue is that these buck converters are not meant to be battery chargers.  Our battery chargers have very accurate current and voltage limits--around 5% for current and less than 1% for voltage, while the buck converters do not have as accurate current limit. 

    The bq24450 and bq2031 lead acid chargers even have a temperature compensated voltage setpoint to properly adjust the charge voltage of lead acid batteries.  I suggest you use one of those chips to charge your battery.  There is a battery charger selection tool here: http://focus.ti.com/en/download/aap/selectiontools/battery-chargers/tool.htm