Need a simple and small PWM generator chip

[Elektro]

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

 

[Leon]

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

 

[Robert Latest]

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.

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

 

[patch]

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.

 

[Nico Coesel]

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

NE555

 

[jasen]

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

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.

 

[Don Lancaster]

You mean like a PIC?

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[Nico Coesel]

You mean like a PIC?

Why throw software at something easely done by some simple analog
circuitry?

 

[Rich Webb]

Why throw software at something easely done by some simple analog
circuitry?

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.