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TPS65981: How to meet safety LPS(Limited power source) requirement with TPS65981 under 20V/5A?

user1874945
Intellectual 300 points
Part Number: TPS65981

Hi TI Expert,

If using TPS65981 for 20V/5A power delivery, how to meet safety LPS(IEC60950-1 2.5 Limited power sources) requirement? Is TPS65981 compliant with IEC60950 as an integrated circuit(IC) current limiter? Or we will have to use PTC or fuse externally to meet LPS?

Thanks.

  • 0
    TI__Mastermind 36756 points

    Hello,

    The TPS65981 is fully UL Certified. The TPS65981 datasheet explains how the over current protection works. You can specifically look at section 9.3.3.11 to see how to configure the PP_EXT to enable OCP as a Source. You would need to use the external power path for sourcing 20V/5A as the internal PP_HV will only support 20V/3A.

    If this answers your question, PLEASE select  This resolved my issue

    Thank you,

    Eric

  • 0 in reply to Eric Beljaars
    Intellectual 300 points

    Hi Eric,

    Thanks a lot for your prompt reply. Since TPS65981 is fully UL certified, do you have the UL certification number or some docs? I can't find this in datasheet or somewhere on TI website. Our safety engineer would need this.

    Dora

  • 0 in reply to user1874945
    TI__Mastermind 36756 points

    Hi Dora,

    You can find TPS65981 UL Cert information in the following link:

    http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=QVGS2.E169910&ccnshorttitle=Protectors,+Low-voltage+Solid-state+Overcurrent+-+Component&objid=1075449610&cfgid=1073741824&version=versionless&parent_id=1074427572&sequence=1

    If this answers your question, PLEASE select  This resolved my issue

    Thank you,

    Eric

  • 0 in reply to Eric Beljaars
    Intellectual 300 points
    Hi Eric,

    Per the UL doc in the link, it shows
    PP_EXT=4.5V-22Vdc, Vbus=1-4A Cont. current, Vbus=1.008-4.915A Prot. current
    PP_HV=4.5V-22Vdc, Vbus=1-4A Cont. current, Vbus=1.007-4.921A Prot. current.

    Suppose Cont. current means continuous current. What's the meaning of Prot. current? Does it mean TPS65981 can't support up to 5A,20V if needs to be LPS certified?

    BTW, I have passed the UL doc to our safety engineer to double check.

    Thanks for your prompt response.
    Dora
  • 0 in reply to user1874945
    TI__Mastermind 36756 points

    Hi Dora,

    UL QVGS2.E169910 tests only devices under 100W. There is a cutoff for testing devices over 100W and under 100W. The Current limit setting we chose to test with the TPS65981 from the datasheet guaranteed we would be just under 100W (98.3W to be exact). The TPS65981 will function identically with a higher current setting.  

    If this answers your question, PLEASE select  This resolved my issue

    Thank you,

    Eric