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Convert analog to PWM-signal?

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Junior Member level 2
Feb 21, 2006
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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.

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.

analog to pwm

Will voltage on pin 1 from figure 1 not be enough to meet your demands ?

P.S. dont upload docs from inet instead give links to them .

**broken link removed**
**broken link removed**

converting analog to pwm


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,

analog to pwm signal

OK, attachments gone :)

And OK, I understand how the PWM-modulation works.

Is it possible and a good choice to use the LM3524 to modulate PWM-signal to drive the motorcontroller-chip TB9060?

PS. I want to control a sensorless BLDC ~100w, 0-10000 rpm, -40 to +~125 celsius

Perhaps the SG3525A is a better chioce, it is possible to adjust v-ref from outside the chip.
**broken link removed**

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!!


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?

converter analog to pwm

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 convert to rpm

Thanks Giri, components ordered...

who knows... maybe it will work :)

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