A DC - DC converter that needs a constant high on the enable pin?
I'm failing to see the use case for this feature.


I use this feature on a similar DC-DC converter, because when the converter is disabled, its current drain is so low. On the converters you mentioned, the spec is max 2&nbsp;uA leakage current when disabled.


  Does this make the IC useless for a voltage regulation on an autonomous battery only powered circuit?


For some battery-powered designs, imho the opposite is true - this feature is especially useful! :-)

That is because you can have a very low-power component (e.g. MCU mostly in sleep or stop mode) which is always powered from the battery, with suitable UVLO / brownout detector. That device then switches the EN pin of the DC-DC converter when required (e.g. depending on an MCU timer or a periodically-checked ADC reading etc.) which then supplies power to the relatively high-power components.

So when the high-power components can be powered-down, this is commanded via the MCU and the DC-DC converter then draws just that maximum of 2&nbsp;uA. For some battery-powered applications (e.g. those with intermittent power usage requirements) that increases the overall battery life, rather than leaving the DC-DC converter running permanently. Having this functionality built-in to the converter removes the need for a separate P-Channel MOSFET switch external to the converter, to achieve a similar type of power-down function.

Summary: That is the "use case" where I have used a DC-DC converter "enable pin" feature. Of course those people who don't need that feature, can use the DC-DC converter with an enable pin in an "always-enabled" configuration.