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Convert analog to PWM-signal?

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Beffo

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analog to pwm

How do I generate a PWM signal from a simple voltage level.

If voltage rises I want a PWM with higher frequency.

EDIT:
I just found the LM3524, that is commonly used in switching power supplies, and can also be used i n other application.... it says in an app. note.

Can I use it to create a PWM signal based on some variabel that i can adjust during operation.
 

v_c

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converting analog to pwm

Beffo,

to generate a PWM signal from a voltage level, you need to put that voltage level into the input pin of a comparator. The other input pin of the comparator will need a sawtooth with a certain magnitude and frequency. The controller IC will usually have a timing resistor and timing capacitor Rt and Ct, that will determine the frequency of the sawtooth. The magnitude of the sawtooth is determined internally by the IC.

The beginning of the PWM pulse is determined by the beginning of the sawtooth and the pulse ends when the voltage level crosses the sawtooth. If you look at the datasheet for the Comparator section you should be able to see this.

Best regards,
v_c
 

Beffo

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vsgiri

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analog voltage to pwm

If voltage rises I want a PWM with higher frequency.

Hey Beffo!
PWM=Pulse Width Modulation.
Pulse width changes in response to input, not the frequency!!

Giri
 

Beffo

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analog til pwm

YES, of course...

It is the duty cykle/time that should be adjusted.

So how about the SG3525A? would it work together with TB9060?
 

vsgiri

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converter analog to pwm

Beffo,
I had a cursory glance through the tb9060.
It just needs the PWM signal, and it generates the 3-phase bridge waveforms.
The PWM could be achieved easily using the 3525.
Just take care of the minimum and maximum pulse widths!
So good luck!

Giri
 

Beffo

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giri convert to rpm

Thanks Giri, components ordered...

who knows... maybe it will work :)
 

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