Low voltage indicator

I hope I’m phrasing this correctly. I would like to build a low voltage indicator (LED) circuit with a 6.6 volt threshold voltage. That is, the light would come on when my battery voltage drops to 6.6 volts. My problem is I can’t find a ‘Supervisor’ for that voltage. Maybe I’m not understanding the nomenclature. Please help. Thank you.

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Welcome to the forum.

This article should help get you started, it’s the classic solution to your problem.


Not even close to what I want

I could not find one at 6.6 Volts either. The closest I can find is part number R5117S001A-E2-KE which has the Threshold voltage of 6.7 Volts. Here is the link: R5117S001A-E2-KE Nisshinbo Micro Devices Inc. | Integrated Circuits (ICs) | DigiKey

Hi dmpanhead,

The adjustable sense voltage TL7700CP supervisor is capable of sensing 6.6V and triggering an output. It requires two resistors to set the trigger voltage, another for a pull-up resistor, and a capacitor to set the output hold-up time.


Max supply voltage is 40V, so no problem there. The sense voltage is 0.5V, so you select resistors R1 and R2 such that the voltage at Vs is 0.5V when the voltage at Vcc is 6.6V.

One note with this part is that it’s output is incapable of driving an LED well, directly, as its maximum output current is 5mA, so you’d have to use it to drive a transistor to get a suitable LED drive current.

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