Looking for >5V pretty fast logic

[Klaus Kragelund]

Hi

I am using a CD4093 with 4 schmitt triggers wired as a free running
oscillator supplied by 10V. The CD4093 is 4000 series CMOS logic, but
it is just too slow for my application (need a 3MHz oscillator/VCO). I
can live with trigger level that has high tolerance and would shift
the frequency since the loop is closed to form a VCO

So been looking at the 74HC and other series, but cannot find anything
that can handle more than 6V and that is fast

Do any of you guys know of a chip? Or perhaps a faster VCO than the
CD4046 PLL. Alternatively building a astable oscillator with 2
MOSFETs. Maybe even a 74HC 5V IC, but with a simple levelshift to get
a fast 10V output

Regards

Klaus

 

[John Fields]

Hi

I am using a CD4093 with 4 schmitt triggers wired as a free running
oscillator supplied by 10V. The CD4093 is 4000 series CMOS logic, but
it is just too slow for my application (need a 3MHz oscillator/VCO). I
can live with trigger level that has high tolerance and would shift
the frequency since the loop is closed to form a VCO

So been looking at the 74HC and other series, but cannot find anything
that can handle more than 6V and that is fast

Do any of you guys know of a chip? Or perhaps a faster VCO than the
CD4046 PLL. Alternatively building a astable oscillator with 2
MOSFETs. Maybe even a 74HC 5V IC, but with a simple levelshift to get
a fast 10V output

 

[Klaus Kragelund]

Good suggestion. The problem is I need it to have low current
consumption and that is difficult to find when it needs to be fast
also (<100ns response)

Right now it looks like a LMC555 can do the trick

Thanks

Klaus

 

[john jardine]

Hi

I am using a CD4093 with 4 schmitt triggers wired as a free running
oscillator supplied by 10V. The CD4093 is 4000 series CMOS logic, but
it is just too slow for my application (need a 3MHz oscillator/VCO). I
can live with trigger level that has high tolerance and would shift
the frequency since the loop is closed to form a VCO

So been looking at the 74HC and other series, but cannot find anything
that can handle more than 6V and that is fast

Do any of you guys know of a chip? Or perhaps a faster VCO than the
CD4046 PLL. Alternatively building a astable oscillator with 2
MOSFETs. Maybe even a 74HC 5V IC, but with a simple levelshift to get
a fast 10V output

Regards

Klaus

The 'HEF' Cmos (eg HEF4093) is twice as fast as the normal stuff.

 

[Joerg]

Hi

I am using a CD4093 with 4 schmitt triggers wired as a free running
oscillator supplied by 10V. The CD4093 is 4000 series CMOS logic, but
it is just too slow for my application (need a 3MHz oscillator/VCO). I
can live with trigger level that has high tolerance and would shift
the frequency since the loop is closed to form a VCO

So been looking at the 74HC and other series, but cannot find anything
that can handle more than 6V and that is fast

Do any of you guys know of a chip? Or perhaps a faster VCO than the
CD4046 PLL. Alternatively building a astable oscillator with 2
MOSFETs. Maybe even a 74HC 5V IC, but with a simple levelshift to get
a fast 10V output

Klaus, check out this one:

http://www.national.com/ds/LM/LM5112.pdf

John Larkin had recently used it in a switcher. Unfortunately it's
around $0.50. Other than the CD4000 series there isn't much anymore that
could run at high voltages. 74HC is usually rated up to 6V.

 

[Jim Thompson]

Klaus, check out this one:

http://www.national.com/ds/LM/LM5112.pdf

John Larkin had recently used it in a switcher. Unfortunately it's
around $0.50. Other than the CD4000 series there isn't much anymore that
could run at high voltages. 74HC is usually rated up to 6V.

Joerg, Nice part! You really ought to find some clientele who can
afford 50¢ ;-)

...Jim Thompson

 

[Joerg]

Joerg, Nice part! You really ought to find some clientele who can
afford 50¢ ;-)

Oh, they all could. But it doesn't always make sense since many designs
are very high volume. Right now I am "discretizing" an IC design because
the trusty old parts might go unobtanium soon and nearly all the
newfangled chips that could replace it are north of two bucks. Heck, we
can get a good bottle of Merlot for that. Ok, I know you don't like the
Shaw brand ;-)

BTW, for the record, it wasn't me but it was John who brought this part
to our attention a few months ago.

 

[Jim Thompson]

Oh, they all could. But it doesn't always make sense since many designs
are very high volume. Right now I am "discretizing" an IC design because
the trusty old parts might go unobtanium soon and nearly all the
newfangled chips that could replace it are north of two bucks. Heck, we
can get a good bottle of Merlot for that. Ok, I know you don't like the
Shaw brand ;-)

Good ol' Upchuck ;-)

Here's my latest favorite Chardonnay... Kim Crawford "unoaked"... $13

BTW, for the record, it wasn't me but it was John who brought this part
to our attention a few months ago.

Thanks, John! I need such parts to convince clients to stick with a
cheap low-voltage process for the main chip and use interface-specific
parts at the loads.

...Jim Thompson

 

[Joerg]

Good ol' Upchuck ;-)

Here's my latest favorite Chardonnay... Kim Crawford "unoaked"... $13

Our favorite winery is this one:

http://coulsonwinery.com/wine_list.htm

Had a Sangiovese yesterday, bottled it ourselves back then. That was a
lot of fun. Unfortunately Ed (seen in the picture) has passed away :-(

Thanks, John! I need such parts to convince clients to stick with a
cheap low-voltage process for the main chip and use interface-specific
parts at the loads.

That was not what National's marketeers intended the part to do ;-)