Re: Micro with 4-independent PWM channels

From: Anton Erasmus (nobody_at_spam.prevent.net)
Date: 01/29/05 

Date: Sat, 29 Jan 2005 17:12:11 +0200

On Sat, 29 Jan 2005 14:07:02 GMT, mw <mw@avoidspam.com> wrote:

>R Adsett wrote:
>> I've had this assertion made to me several times. So far no-one has been
>> able to back it up. A CPLD capable of holding 4 10 bit PWMs always seems
>> to be rather more expensive than a few dollars (You still have to add A/D
>> micro etc and fit in the $6 range remember).
>>
>> From what I've seen so far it's always cheaper to add another micro to
>> act as a PWM peripheral that to add a CPLD to do the same thing.
>>
>> That's not to say it's impossible, but so far no-ones been able to
>> demonstrate that it's doable.
>>
>> Robert
>
>Agreed. Why doesn't someone sell a dedicated chip as a PWM expander?
>It would be nice to find a SPI or I2C - compatible chip with 6 to 8 PWM
>outputs, at least 14 bits, for LED lighting applications. Preferably in
> a 14 or 16 -pin package, 5V compatible outputs.
>
>All the micros are skimpy on hi-resolution PWM outputs.
>

For LED Driving applications Maxim makes a number of ICs which can
directly drive numerous LEDs. The current can be set individually for
each LED. It does not use PWM, so for EMI it is better. Look at
something like the MAX6957AAI, available at Digikey in small
quantities.

Anton Erasmus

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