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Logic control exists in LDO

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alphacat

New Member
Hello,

Up until now I treated LDOs as black boxes which receive a certain voltage and produce constant (lower) voltage.

I started reading a bit about its construction and I saw it uses a Logic control.

What is this logic control for?
And what is the device that the logic control feeds?

Thank you.

9062-LDO.png
 
Last edited:

Speakerguy

Active Member
Logic control is probably things like over-current and over-temperature limiting. Even very old regulators like the 7805 or 317 feature things like this.

The rest of the circuit is just the analog feedback path that the logic control can disable. PMOS pass transistor, voltage comparator, internal voltage reference being compared to the voltage at the feedback/adjust pin.
 
Last edited:

ericgibbs

Well-Known Member
Most Helpful Member
Hello,

Up until now I treated LDOs as black boxes which receive higher voltage and produce constant (lower) voltage.

I started reading a bit about its construction and I saw it uses a Logic control.

What is this logic control for?
And what is the device that the logic control feeds?

Thank you.

The logic is part of the ENABLE circuit, controlled from the Enb pin, to on/off the device.
 
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