OPA552: Solution using a Op Amp to convert PWM to DAC?

David__

Genius 3585 points

Part Number: OPA552

Hi, all.

After trying the SLAA869, I was curious about converting a PWM signal as a DAC output using Op Amps.

I did notice videos using low pass filters to create a DAC output.

However, I noticed the RC delay effect when starting the system.

Just by curiosity, instead of purchasing TI's awesome DAC chips, is there a better solution in accuracy from TI by using Op Amps or transistors?

I couldn't find an application note from TI.

over 5 years ago

0 Tim Green1 over 5 years ago

TI__Expert 6275 points

Not sure exactly what you are trying to achieve here? Attached is a good app note on how to scale PWM to analog if it helps.

TIDU027.pdf

0 David__ over 5 years ago in reply to Tim Green1

Genius 3585 points

Thanks, Tim. Since the TIDU027 (Microcontroller PWM to 12bit Analog Out) says that

- The main goal of this design is to convert PWM to analog output and achieve a 12 bit resolution with a ripple signal less than one half LSB.

- A secondary goal is to develop a circuit that amplifies the output ripple (error) to a level that an oscilloscope can measure.

I appreciate your help! This is what I was looking for!

2867.schematic.pdf

By using the TIDU027's schematic, which has 4 RC filters and two Op Amps, this means that I can generate a 12-bit DAC with a PWM input, right?

0 kai klaas69 over 5 years ago in reply to David__

Guru 140200 points

Hi David,

keep in mind that a PWM based DAC can create lots EMI and signal ground noise. Remember that the PWM togglings must never stop. Because of this I would always use a "real" DAC.

Kai

0 David__ over 5 years ago in reply to kai klaas69

Genius 3585 points

Wow, never expected that coming. Thanks for noticing me!

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OPA552: Solution using a Op Amp to convert PWM to DAC?