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12V, 2.4A Step-Down Voltage Regulator D36V28F12?

Am i correct in reading the discription that it includes a low voltage cutoff?

My follow up question is how does one control the point at which this goes into a “sleep mode”.

I ask because im looking for something similar to item 2968 the fine adjust stepup step down regulator.

I have several and they work great just looking for something pretty much the exact same but with 12 V?

any help appreciated

Hi.

The D36V28F12 step-down regulator does not include a low voltage cutoff, but you could add one by creating a voltage divider. There is already a 100k resistor between VIN and EN, so you would just need to add an appropriate resistor between EN and GND. To get a cutoff around 12V, you could add an 11k resistor.

-Claire

Hello Claire, thank you for your reply, Ok if that is the case, i have to ask becuase i dont know the maths here. I will be using this with a 3s lipo running at 12.6v fully charged. I would like to get it to cut off at 10.2 volts. so a comfy 3.4v per cell hopefully.

In the link to the regulator there is a pinned note that says custom work can be done. is this something i can have pololu do for me?

Sorry, after looking into this more, I realized I confused this with a different design, and unfortunately, this regulator would need more than just a resistor added to get any predictable low-voltage shutoff.

-Claire

Hi again.

I talked to a few other engineers here about something that was unclear in the datasheet for the chip used on the D36V28F12. We concluded and then confirmed through testing that the EN threshold does seem consistent enough to use a voltage divider to get a low-voltage cutoff.

The EN threshold for a falling voltage is typically 1.2V, the threshold for a rising voltage is typically 1.35V, and the EN pin is pulled up with a 100k resistor. To get a cutoff of 10.2V, you can connect a resistor around 13k between EN and GND. This will mean the regulator will not turn on until VIN goes above about 11.5V, so whether that will work for you will depend on the rest of your requirements.

By the way, we have seen that the ideal charge and discharge thresholds for LiPo batteries (from a longevity perspective) is about 4.15V/cell charged and 3.7V/cell discharged, which is a smaller range than the 1.2V and 1.35V thresholds I just mentioned. You will also have voltage drops in your wiring that will vary with the current, so you might need something more reliable to optimally protect your battery.

Sorry about the back and forth and any confusion.

-Claire

Oh Sweet thank you for that research and info. Greatly appreciated.

would a 13k Thick film 1/10w resistor work i would like something small to fit the form of the board.

That should be fine. The resistor will not see any significant currents, so it doesn’t need to be high power.

-Claire