MC34063 vs MC34063A types

Hi all,

I am looking for the actual difference between MC34063 vs MC34063A;

I have the idea that the "A" type allows setting of the output latch anywhere in the "T-on" period, while the "non-A" only conducts for the full T-on period.

It seems remarkably hard to verify this in data sheets I managed to find while googling.

While I am at it, I see a lot of std applications where the current limiting mechanism of this chip (limiting T-on) will drive the switching frequeny way above the specified 100 KHz limit. Specifically in buck applications, the freq close to max load is for fair bit dependent on T-off, so that Fmin needs to be calculated a lot lower than 100 Khz. Any advise here?

Anybody knows where to find the truth? TIA!

I read in sci.electronics.design that René wrote (in ) about 'MC34063 vs MC34063A types', on Fri, 30 Sep 2005:

E-mail.

Oh, never do that. Make up a notepaper heading in Word and become 'Renelectronics International Designs'. Or something.

I didn't mean to brush you off. I asked **whether** asking the manufacturer was an option. You might have already tried and failed, or were not satisfied for some reason.

As in reading the datasheets from various vendors? All I can find is A types. But I have also a non A-type spice model so it must exist somewhere.

Privately calling a manufacturer from Holland is an option off course

- but more costly than using this newsgroup. Or approaching a sales rep (as a private person)?

Never underestimate my simplicity. Some kind soul might educate me in a few monosyllabic words. But then again - I might not deserve it. Sorry to waste your time.

This could very well be. However the intriguing point is that I downloaded some spice models from ONSEMI, and this model yields 2 selections that actually behave differently. The onsemi datasheet does not make any mention of a difference, nor does the AN920 application manual seem to carry any info here. (unless I skipped it somehow - which is also known to happen :-)

BTW - fun to simulate these workhorse parts; for me it was a lot more instructing than making the calculations. There seems to be a large room for optimalisation towards specific uses of this very cheap part.

Could it be a second cut of the die, with the exact same specs? I know that there are certain manufacturers will append a letter to the part number when they revise the silicon.