shut down supply voltage comparator

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yassin.kraouch

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i have an external battery ( 12V) that supply a developpement board throught a DC-DC converter, i want that if the voltage of the battery is below 12V i force DC-DC chip to not work, have you an idea about this ?
 

Hi,

you need to have an another reference(low power, commercial battery) and to compare it with your battery and then drive a MOS transistor to shut down the supply of the development board.
Or to use a chip with a shutdown integrated.
Hope it helps you.
joseMiguel
 
is there any method to be used in without shut a reference ?
 

You need a voltage monitor circuit, when it detects voltage below a certain level, it disable dc-dc converter through its enable input. A series transistor can also switch off power to dc-dc converter.

TL431 Battery Voltage Monitor - Storage


In this circuit disconnect R3 from +ve and connect to base of series pnp transistor to disconnect 12v supplying to converter circuit.
 

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Last edited:
You mean that i should connect the base of a transistor in Ve and the emitter to the cathod of LM431 ? and the collector to the input ?
 

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