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
