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Original question:

TPS25982: Max Cout value of TPS259827

TPS25982: SOA and max Cout

Hanno Reimer
Intellectual 1920 points
Part Number: TPS25982
Other Parts Discussed in Thread: LM5069

What is the max value of Cout for TPS259827, operated at Vin=24V? I saw this question already in the forum, but the discussion went to private. 

Could you please provide a diagram with the SOA of the internal FET? 

For industrial 24V rails an OVLO >=26V would be an very interesting feature! Do we've such a device on our roadmap? 

  • 0
    TI__Guru** 105361 points

    Hi Reimer,

    If the load is only purely capacitive during startup, there is no limit on the amount of Cout. You can increase dv/dt capacitor value to reduce Vout slew-rate (and hence inrush currents) to support large Cout.

    What is the target Cout ?

    We won’t provide SOA data for any of our integrated devices because we always ensure device protection through inbuilt over temperature protection.

    For roadmap, please email me.

    BR, Rakesh

  • 0 in reply to Rakesh
    Prodigy 70 points

    Hello Rakesh

    We (industrial customer of Hanno) are currently developing a new universal power supply.

    With regard to the IEC 62368-1, this power supply should have 6 separate output voltages, which have a eFuse / Hot plugging characteristic

    • Our current systems (controllers with external FET) are for switching on a capacity of max. 4700μF specified.
    • In addition, when switching on we assume a load current of 24V / 24Ohm = 1A.
    • Switching on thus has an ohmic (=> 1A) and capacitive (=> 4.700µF) component.

    For the TPS259827LNRGE we have considered a current limit of 6A, with short-term currents (ca. 50ms)  up to 9A should be possible.

    So far, we use the PSMN7R6-100BSE.
    Without an overview of the SOA, we can not currently assess the limits of the IC

    Can the TPS259827LNRGE turn on a 4.700μF / 1A load? Where are the limits?

    Best Regards

    Ralf

    koerfer.ralf@scheidt-bachmann.de

  • 0 in reply to Ralf Koerfer
    TI__Guru** 105361 points

    Hi Ralf,

    Welcome to E2E and thanks for sharing the information

    We have design calculator to check the load boundaries during startup. It is available at http://www.ti.com/product/TPS25982/technicaldocuments

    Please use that and let me know if you have any questions.

    BR, Rakesh

  • 0 in reply to Rakesh
    Prodigy 70 points

    Hello Rakesh,

    Using the Excel tool and Figure 53 (data sheet page 34), the max. Output capacity can be determined.

    • At VIN = 24V and a load current of approx. 0.5A   => max. Output capacitance of approx. 265μF (@CdV / dt = 10nF).
    • At VIN = 12V and a load current of approx. 0.5A,  => max. Output capacitance of about 1,800μF (@CdV / dt = 22nF).

    For our application, these values are too small, we continue to take the LM5069.

    Best regards

    Ralf

  • 0 in reply to Ralf Koerfer
    TI__Guru** 105361 points

    Hi Ralf,

    Understood.

    One way is to use PG signal to enable the downstream load so that during startup the load will be purely capacitive which can be handled with appropriate CdV / dt.

    BR, Rakesh

  • 0 in reply to Rakesh
    Prodigy 70 points

    Hello Rakesh,


    Thank you for your feedback signal.
    • With TPS259827, at IOUT = 0A only max. 600μF switch-on capacity possible.
    • In our applications we need a higher performance.

    This efuse is a very interesting IC especially with regard to the IEC 62368-1 certification.
    It would be nice if Texas Instruments could include a more powerful version in their product program in the future:
    Ideally  with integrated FET and enhanced SOA:
    • VIN = 28V Recommended, absolute max. 35V
    • IOUT = 15A
    • COUT = max. 2,000μF with additional ILOAD  = 0,5A

    Can you please close the ticket.

    Best regards
    Ralf