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Confused about V_o(out) range: error in Abs. Max. of several TPS20xx power-distribution switches?

Other Parts Discussed in Thread: TPS2082, TPS2013, TPS2010, TPS2011, TPS2012, TPS2034, TPS2024, TPS2030, TPS2031, TPS2032, TPS2033, TPS2023, TPS2022, TPS2092, TPS2097, TPS2087, TPS2095, TPS2085, TPS2090, TPS2081, TPS2080, TPS2054B, TPS2051B, TPS2065, TPS2043B, TPS2061, TPS2062, TPS2067, TPS2044B, TPS2066, TPS2063, TPS2053B, TPS2052B, TPS2052C

This is a long and slightly involved question, but several datasheets are very confusing to me. I'm considering power-distribution switches from the TPS20xx family for an application where the IN pin may float or see reverse output voltages as 0 =< V(IN) < V(OUT) =< 5.5 V. My question is: can I use the TPS2082?

The reason for asking is that the TPS2082 Abs. Max. Rating of V_O(OUTx) Output voltage range is -0.3 to V_I(IN) + 0.3 V, meaning essentially no reverse voltage is allowed. This would be no surprise with a 'regular' MOSFET, due to the parasitic body diode. However, the somewhat unusual MOSFET symbol in the functional diagram suggests these parts do not have the parasitic diode of 'regular' MOSFETs. By contrast, several other parts in the TPS20xx family do have a 'regular' MOSFET  represented in the functional diagram (e.g. TPS2010, TPS2011, TPS2012, TPS2013, doc. SLVS097A). Thinking I was misreading the artwork in the functional diagram, I compared the datasheets of several other TPS20xx parts. Now I suspect the diagram is correct, and the Abs. Max. Output voltage range may be wrong (too restrictive), and several TPS20xx parts may have broader applications than currently specified. I could get some sample parts and test them, but I will not design against the published Abs. Max. R., no matter how a few samples may test. Hence the need for this question, and perhaps a clarification/correction in the datasheets.

Here is what I gather from the datasheets:

- TPS2030, TPS2031, TPS2032, TPS2033, TPS2034 (datasheet SLVS190C) and TPS2022, TPS2023, TPS2024 (SLVS175C): these parts are explicitly described as featuring "No Drain-Source Back-Gate Diode", have the 'unusual' MOSFET symbol in their functional diagrams, but the Abs. Max.  V_O(OUTx) Output voltage range is again -0.3 to V_I(IN) + 0.3. No other relevant number. If this is all correct, what is the purpose of the advertised "No Drain-Source Back-Gate Diode" feature?

- TPS2080, TPS2081, TPS2082, TPS2085, TPS2086, TPS2087 (SLVS202B) and TPS2090, TPS2091, TPS2092, TPS2095, TPS2096, TPS2097 (SLVS245C): a "No Drain-Source Back-Gate Diode" feature is not mentioned explicitly, but it is shown in the functional diagram. What is interesting, it is described as a Bidirectional Switch, and the Elec. Char. specify a 0.3 uA 'Reverse leakage current' at INx = high impedance and V_I(ENx) = 0 V or V_I(ENx) = VI(IN). However, the Abs. Max.  V_O(OUTx) Output voltage range is -0.3 to V_I(IN) + 0.3. Does this mean that reverse voltage (max. 0.3V) is allowed only when the switch is enabled? How weird.

- TPS2043B, TPS2044B, TPS2051B, TPS2052B, TPS2053B, TPS2054B (SLVS514L) and TPS2061, TPS2062, TPS2063, TPS2065, TPS2066, TPS2067 (SLVS490I): the "No Drain-Source Back-Gate Diode" feature is not mentioned explicitly, but it is shown in the functional diagram. What is more, the Elec. Char. specify a 0.2 uA 'Reverse leakage current' at V_I(OUTx) = 5.5 V, IN = ground. Consistently, Abs. Max.  V_O(OUTx) Output voltage range is -0.3 to 6 V. Hurray! These last datasheets are finally making sense: the MOSFET of this 'unusual' kind has no parasitic diode, reverse voltage is allowed and leakage is specified and negligible. Too bad the configuration of these devices is not the same as the TPS2082, so I would need two single-channel devices instead of one. However, these devices all look very close variations of the same underlying design, so perhaps the Abs. Max. Output voltage of the TPS2082 and many (not all) other TPS20xx should be -0.3 to 6 V instead of -0.3 to V_I(IN) + 0.3 V.

Do I misunderstand the documentation, or several datasheets should be revised to relax the Abs. Max.V_O(OUTx)? Above all, can I use the TPS2082 as a bidirectional switch with occasional reverse IN-OUT voltage of 5.5 V max?

Best regards,

Michele

  • Thank you for your thorough review and analysis. The TPS20xx families are quite old and I was not able to find an answer to the OUT specification with respect to IN. I'll keep looking and let you know if I find anything out.

    We would recommend using the newer family of distribution switches like TPS2052C. This is a dual, but has a common input pin so may not work if you have independent input sources. The TPS2052C operates with 5V buses while the TPS2052B can operate from 3.3V and 5V input bus's.

  • Hi Eric,

    after going through several posts, you seem to be the specialist for the TPS Family.

    Here is a piece of Bug for you crush:  

    We have designed a board using TPS2080D. In this design, it is very crucial that the chip sets the OC-Signal when the Load requires current over 1A. All USB-Ports seem to work just fine. The thermal short down function works also fine.

    However, i am missing the active low signal of the OCS! Just like in the datasheet, I used 4Ohm Load, the OCS-Pin remains always High! Same with 3Ohm Load, 2Ohm Load already sets the thermal short down function.

    My question at this point is, was this actually tested as described in the Datasheet?

    If yes, could you connect me to a german Specialist from TI for verification, we need to get this cleared as quickly as possible.

  • Hi Richard,

    Given that this question is of a different topic than this original thread, I would ask if you can please post this as a new thread in Power Interface? This will avoid confusion and help us keep track of this question.

     

    Please post here:

    http://e2e.ti.com/support/power_management/power_interface/f/204.aspx

     

    Thanks!

    Alex