Hello
I'm looking for a simple and small size PWM generator chip. I want it to have a selectable frequency of about 5 kHz and the duty cycle must be externaly controlled (0% - 100%) by a voltage or current.
Help please :-)
Hello
I'm looking for a simple and small size PWM generator chip. I want it to have a selectable frequency of about 5 kHz and the duty cycle must be externaly controlled (0% - 100%) by a voltage or current.
Help please :-)
You could use a suitable MCU, like a 16F88 PIC or a Tiny2313 AVR.
Leon
Comparator + sawtooth generator. DC set by using control voltage as threshold. Complexity depends on how linearly DC scould follow control voltage. Doable with an SO8 chip + a few discretes. Then of course there's the full range of UC* PWM control chips from TI (formerly Unitrode), but they won't do 0% or 100% DC because it doesn't make sense for power apps.
robert
There are PWM chips available that you can control digitally. Alternatively, you can use 2 op-amps to generate a variable frequency triangle wave and a comparator to generate the PWM.
Elektro wrote:
NE555
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this sort of thing can be done with a dual op-amp, one half is setup to generate a sawtooth at 5Khz the other compares it to the input.
-- Bye. Jasen
You mean like a PIC?
-- Many thanks, Don Lancaster voice phone: (928)428-4073
Why throw software at something easely done by some simple analog circuitry?
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It depends a lot on the application, but a software controlled PWM can be a little easier to implement if one needs things like a full power start for n seconds, a minimum/maximum duty cycle floor/ceiling, or a particular non-linear response. All certainly do-able with just silicon but, again depending on the app, possibly simpler or cheaper with a tiny microcontroller.
-- Rich Webb Norfolk, VA
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