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Convert 0..5v PWM to 6,5..11,5v
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Zero999:

--- Quote from: Benta on December 27, 2018, 07:44:42 pm ---The OPA342 will not operate at 12 V. You'll need replacement smoke...

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Whoops, I meant the OPA172, not the OPA342, which as you correctly stated has a maximum supply voltage rating of 5.5V.

--- Quote from: Benta on December 27, 2018, 08:26:15 pm ---
--- Quote from: SiliconWizard on December 27, 2018, 08:06:02 pm ---
--- Quote from: Benta on December 27, 2018, 07:44:42 pm ---The circuit also has a DC gain of over 1. Don't know if that's desired.

--- End quote ---

Yes, it has a gain of 2. Because the summing network (R4, R5) actually divides the sum by 2. :)

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No it doesn't. Do the math.


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No, the summing network divides the signal by just over 2. I can't be bothered to work out the exact figure at the moment. You work it out, if you want to know. Hint: R1 and R4 have an impedance of 110k and  R2, R3 and R5 have an impedance of 105k454.

I'd do something like this. The PWM frequency and ripple requirements weren't stated, so I didn't bother calculating the values of the filter components. I just plugged some values in which didn't cause any overshoot and gave a nice flat output in LTSpice.


EDIT: I forgot the pre-filter. See my next post for the updated schematic.
SiliconWizard:

--- Quote from: Benta on December 27, 2018, 08:26:15 pm ---
--- Quote from: SiliconWizard on December 27, 2018, 08:06:02 pm ---
--- Quote from: Benta on December 27, 2018, 07:44:42 pm ---The circuit also has a DC gain of over 1. Don't know if that's desired.

--- End quote ---

Yes, it has a gain of 2. Because the summing network (R4, R5) actually divides the sum by 2. :)

--- End quote ---

No it doesn't. Do the math.

--- End quote ---

It approximately does. Not exactly ok, but it's close enough and limits the number of different resistor values. I get something like 11.6V for a 5V input. The op didn't state its requirements in terms of accuracy. You can always calculate resistor values for a more accurate overall gain if needed, but I didn't see the point. Given the need of the op, it didn't seem like he needed a precision design.

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Calculated to get theoretical figures: I get approx.:
Vout = 6.68 + 0.98*Vin

Note: you can replace R4 with a 95.3k resistor (existing value, but of course more expensive) to get better accuracy: Vout = 6.54 + 1.00*Vin
Zero999:
I forgot a pre-filter is required, otherwise high frequencies will get through the Salen-Key filter, as the op-amp has a finite bandwidth. R4 can be split and another capacitor added.
mikerj:

--- Quote from: SiliconWizard on December 28, 2018, 12:13:49 am ------
Calculated to get theoretical figures: I get approx.:
Vout = 6.68 + 0.98*Vin

--- End quote ---

That is a gain of less than 1.
Jan Audio:
I think i go with SiliconWizard schematic :
Can it be used for DAC signal also ?
Can it be used for whole range ?



@Zero your circuit is wrong, the PIC16 can not have more then exact 10K for impedance, it can charge not decharge, pulldown resistors required.
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