Voltage Level Shifting

[Katy1163]

I am trying to figure out the best way, with the least number of components to translate a voltage from -12V-5V to 0V-5V. I am using a comparator to compare negative voltages and the only negative voltage I have available to me on my board is -12V, so I have to use this voltage to supply the comparator. I am able to get the +5V with a pullup, but my low level output is -12V. I am going into some CMOS Tinylogic gates that only accept -0.5V to 7V for inputs. Any help would be appreciated!

 

[sreid]

A voltage divider using resistors. Say, 1k Ohm to 5V and 2.4K to the comparator output.

 

[VEBill]

"...from -12V-5V..."

The 2nd '-': minus or dash? In other words, is that -12v to -5v, or -12v to 5v? I assume the latter.

Perhaps all that it required is a diode to block the minus voltages, effectively turning minus into zero. In other words, -12v to +5v, through a diode, becomes 0v to +5v.

You might (?) need a resistor (100k?) to swamp out the input Z if high in reverse bias.

 

[melone]

Are you trying to convert from RS232 to TTL? If so, you can buy that online...

 

[Katy1163]

Yes I am talking about -12V to 5V....and no I am not converting between RS232 and TTL. But I have actually found a solution to my problem that does not require any voltage translation. Thank you for the suggestions, though!!

 

[melone]

What is it? Perhaps we could all benefit from it.

 

[DHambley]

please tell us your solution. I was going to suggest a dual voltage-supply comparator like the AD8564 but that would require reducing the neg rail to -9V and using resistor dividers.

What was you solution?

DH

 

[GonzaloEE]

I think he's got it patented

 

[danonboost]

Why not explain the solution in detail (and the problem for that matter)? That is the entire point of this community.

 

[MacGyverS2000]

A "solution" could have been a rearrangement of the problem itself, rather than solving the original problem. Such as removing the need for comms altogether...

Dan - Owner

http://www.Hi-TecDesigns.com