1. Identify the regulator reverse-current path
Reverse current in TI's LDO discussion flows from the output towards the input, opposite to the usual supply-to-load direction. The article identifies a parasitic body diode associated with the pass FET as a possible path. Recognizing that path is essential: stopping normal regulating action is not the same architectural statement as removing every route through the regulator from output to input.
TI explains that the connection of the pass transistor's bulk contributes to this parasitic-diode context. The reverse-current question therefore reaches into the pass-element architecture, rather than being answered solely by the presence of an error amplifier or voltage-regulation function. A candidate can have an ordinary regulation description without that description establishing how its internal path behaves under reverse conditions.
Begin the selection question with the protected boundary. Is the concern current traversing the regulator internally, or current reaching the supply behind it? Both can be described informally as reverse current, but they do not require an identical explanation. Defining the boundary first makes the different methods in TI's article understandable without assuming a universal protection function for every LDO or prescribing a circuit connection.
2. Distinguish bypassing the LDO diode from blocking the supply
TI describes an output-to-input Schottky diode that provides a path around the regulator's body diode during the described reverse condition. The important distinction is bypassing that internal path. It should not be renamed as blocking all current towards the input: the method provides a different route for reverse current, rather than establishing that the upstream supply cannot receive it.
The article contrasts this with a diode before the LDO, intended to prevent current returning into the supply. That changes the boundary being protected. It also introduces a forward-path voltage consequence, because the supply-side diode affects the input needed for regulation. The two approaches cannot be compared meaningfully through one protected checkbox while those different current paths and headroom effects disappear.
Consider a requirement concerned specifically with protecting the upstream rail from backfeed. Evidence that a method diverts current around the regulator's internal diode does not by itself answer that requirement. Conversely, an input-blocking description must be considered with its forward supply implications. This is an architectural comparison of what each approach changes, not an instruction to add either diode or a guarantee for the customer's supply sequence.
3. Compare integrated pass-element protection architectures
Integrated reverse-current protection can also use different pass-element arrangements. TI describes adding a second FET so that the body-diode orientations oppose one another, with control responding to the reverse condition. The article associates that arrangement with a dropout trade-off. The useful selection distinction is that an added blocking function can alter the forward-path requirement as well as the reverse path.
TI then describes a different bulk connection intended to eliminate the source-connected parasitic-diode arrangement. In the article's named context, that approach avoids the same dropout increase. These descriptions identify different integrated mechanisms. A statement that protection is built in does not reveal which mechanism a candidate uses or which forward-path consequences its own documentation specifies.
Keep the architecture explanation attached to the exact regulator description. The article's examples demonstrate why reverse protection and headroom can interact differently, rather than supplying a common internal design for all protected LDOs. This comparison does not assign an ON-state, OFF-state or absent-supply guarantee to another device. Those details remain properties of the particular implementation and its documented operating conditions.
4. Separate required protection from ordinary LDO specifications
Ordinary LDO selection fields retain their own purposes. Dropout concerns forward headroom; the reverse-current question concerns what happens when the output-to-input condition drives current the other way. An attractive dropout description cannot identify a parasitic path or prove that a candidate prevents upstream backfeed. Likewise, identifying a reverse-protection mechanism does not complete the regulator's forward operating requirements.
This creates a practical comparison between two responsibilities. The regulator must meet the intended forward supply requirement, while the selected protection must address the particular reverse boundary. A proposal that adds supply-side blocking can change headroom. A proposal relying on an integrated architecture can introduce a different relationship. Each should be described through the mechanism it actually uses, rather than grouped only by the low-dropout category.
Finish by distinguishing the internal path, the upstream boundary and the associated forward-path consequence. That is more precise than transferring a load-switch family's ON/OFF statement to a regulator. It also keeps the selection centred on LDO architecture rather than repeating a general power-state checklist. No universal reverse-current threshold, protection timing or accepted implementation follows from these qualitative methods; the exact candidate must support the required boundary.
Sources and further reading
TI SSZT658, LDO Basics: Preventing Reverse Current, physical pages 1–5, qualitative path and architecture descriptions. Figures, component values, implementation instructions and universal ON/OFF protection claims are not used.