How to change voltage level 9-24 volts to 0-3.3 volts

[chethan2689]

Hi,
I am new to hardware design, i am using internal ADC MCU this voltage range is 0 to 3.3 volts but input voltage is 9 to 24 volts, anyone can give me the solution how convert this voltage level.
conversion level:
input output
less than or equal 9 volts = 0 volts
- -
greater than or equal to 24 volts = 3.3 volts

waiting for your reply

Thanks and regards,
chethan kumar

 

[D.A.(Tony)Stewart]

Hi,
I am new to hardware design, i am using internal ADC MCU this voltage range is 0 to 3.3 volts but input voltage is 9 to 24 volts, anyone can give me the solution how convert this voltage

Thanks and regards,
chethan kumar

your transfer function is

Vout = ( Vin -9V ) * 3.3/15 = Vin * 3.3/15 - 9*3.3/15

This can be done a number of ways with a reference voltage (9V or 1.98V) with a differential input and resistor ratios using a rail to rail Op AMP with 3.3V. Often ADC's have a free Op Amp included for level shifting.

Pay attention to behavior for saturated inputs (<9,>24)and consider using Sch. diode clamps if necessary from OA inputs to both rails.

 

[kokanepd]

you can use the zero crossing circuit with reference voltage of 9v.for this circuit vcc=3.3v and vss=0v

 

[ku637]

Is this the circuit you are looking?

When input is 9V.

When input is 24V

Best Regards