3.3 VDC PWM to 5 - 1 VDC Analog

[Zexston]

Hello all,

I need to convert a 3.3 VDC PWM signal (PWM freaquency adjustable if needed, but not duty cycle) to an anolog output of 5 to 1 VDC (PWM max duty cycle = 1 VDC, Min duty cycle = 5 VDC).

I don't want to add a micro controller to do this, but my op amp skills have not been used since in school.

I've a got a non-inverting op amp circuit with a RC low pass filter made that converts the PWM to a 0 to 5 VDC analog(PWM minduty cycle = 0 VDC, Max duty cycle = 5 VDC).

My question: How do I convert this 0 - 5VDC analog signal to a 5VDC - 1VDC signal?

Any help greatly appreciated!:grin:

 

[GUMY]

1. Reduce gain on op amp to get 0-4V output.
2. Add differential amplifier with gain=1. Connect 5V to + input and 0-4V signal to - input.

 

[jiripolivka]

The problem in your task is no information about the DC load. As your input PWM signal is AC, you can use a rectifier to get DC, then use a Zener to get a proper voltage.