conversion of 0 to 12V square wave to 0 to 3.3V square wave

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LavanyaThumati

Joined Sep 22, 2020
25
Hii
I need to design a circuit in which 0 to 12V square wave (32KHz) should be converted 0 to 3V3 or 0 to 5V square wave(32KHz) which is given as input of the IO pin of Microcontroller or FPGA . Can anyone suggest me circuit for this ...

I have a thought of using voltage divider... This can be used for DC voltages
are the below circuits can be used

1612691152758.png

1612691571684.png
 

jpanhalt

Joined Jan 18, 2008
11,088
There are lots of designs for level shifters. Here's one that XBee uses:

1612692572922.png

What's wrong with the first (mosfet) circuit you show, aside from inverting the signal? You might want to add a pull-down resistor on the gate to be sure it turns off (depends on source impedance).
 

BobTPH

Joined Jun 5, 2013
3,493
If you can rely on the max voltage, a simple two resistor divider should be fine. Use about 10K for the lower resistor and the builtin diodes on the input will give adequate protection.

Bob
 

wayneh

Joined Sep 9, 2010
17,153
Ditto. Why complicate it? The input impedance load of your IO should be very high, so two resistors is all you need.
 
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