Forums

Low RDSon Logic CMOS Gate

Started by Klaus Kragelund October 1, 2012
"Klaus Kragelund" <klauskvik@hotmail.com> wrote in message 
news:7af37d77-1d1a-4b30-8e74-92c50e08c772@googlegroups.com...
Hi

>I need a CMOS gate with low voltage drop at about 30mA current source and >sink. The tiny logic NL27WZ14 has 600mV drop at >32mA which equates to >18ohm RDS on. >I am searching for a device with less than 5-10 ohms and it would need to >be ok to parallel to get lower resistance. Also, it must not >have to much >crossover shoot-through (so probably schmitt trigger type) and must have >low dissipation at high operational >frequency (1-10MHz) >Any one have a part in mind?
Consider low Rds switches/muxes from AD, TI or Maxim. Sub 1-Ohm Rds is available; break-before-make operation guaranteed. Vladimir Vassilevsky DSP and Mixed Signal Consultant www.abvolt.com
On Oct 1, 1:33=A0pm, Klaus Kragelund <klausk...@hotmail.com> wrote:
> Hi > > I need a CMOS gate with low voltage drop at about 30mA current source and=
sink. The tiny logic NL27WZ14 has 600mV drop at 32mA which equates to 18oh= m RDS on.
> > I am searching for a device with less than 5-10 ohms and it would need to=
be ok to parallel to get lower resistance. Also, it must not have to much = crossover shoot-through (so probably schmitt trigger type) and must have lo= w dissipation at high operational frequency (1-10MHz)
> > Any one have a part in mind? > > Thanks > > Klaus
http://www.intersil.com/en/products/switches-muxs-crosspoints/low-voltage-s= witches/switches-muxs-crosspoints/ISL43L210.html (from John Devereux, earlier this year) Break-before-make. DigiKey had competing parts, too. -- Cheers, James Arthur
On Mon, 1 Oct 2012 12:54:49 -0700 (PDT), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

>On Monday, October 1, 2012 9:28:11 PM UTC+2, Jim Thompson wrote: >> On Mon, 1 Oct 2012 12:15:09 -0700 (PDT), Klaus Kragelund >> >> <klauskvik@hotmail.com> wrote: >> >> >> >> >On Monday, October 1, 2012 8:07:17 PM UTC+2, Jim Thompson wrote: >> >> >> On Mon, 01 Oct 2012 10:44:44 -0700, John Larkin >> >> >> >> >> >> <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >> >> >> >> >> >> >> >> >> >> >> >On Mon, 1 Oct 2012 10:33:00 -0700 (PDT), Klaus Kragelund >> >> >> >> >> >> ><klauskvikddd@hotmail.com> wrote: >> >> >> >> >> >> > >> >> >> >> >> >> >>Hi >> >> >> >> >> >> >> >> >> >> >> >> >> >>I need a CMOS gate with low voltage drop at about 30mA current source and sink. The tiny logic NL27WZ14 has 600mV drop at 32mA which equates to 18ohm RDS on. >> >> >> >> >> >> >> >> >> >> >> >> >> >>I am searching for a device with less than 5-10 ohms and it would need to be ok to parallel to get lower resistance. Also, it must not have to much crossover shoot-through (so probably schmitt trigger type) and must have low dissipation at high operational frequency (1-10MHz) >> >> >> >> >> >> >> >> >> >> >> >> >> >>Any one have a part in mind? >> >> >> >> >> >> >> >> >> >> >> >> >> >>Thanks >> >> >> >> >> >> >> >> >> >> >> >> >> >>Klaus >> >> >> >> >> >> > >> >> >> >> >> >> >Use something like an HC14, with one section buffering the input, then >> >> >> >> >> >> >driving several other sections, up to 5, in parallel. >> >> >> >> >> >> > >> >> >> >> >> >> >More extreme on speed - sub ns edges - would be an NL37WZ17US, again >> >> >> >> >> >> >with one section buffering the input to drive the other two. >> >> >> >> >> >> > >> >> >> >> >> >> >> >> >> >> >> >> I don't think that will fix shoot-thru. 'HC14 only fixes slow inputs, >> >> >> >> >> >> so maybe the simple-minded solution is to simply slow down the input >> >> >> >> >> >> to get firm turn-off of drive-low before drive-high (and vice-versa) >> >> >> >> >> >> is activated... say take 10-20ns to get thru the hysteresis ?:-) >> >> >> >> >> >> >> >> >> >> >> >> Or maybe a 1/2-H bridge driven by non-overlapping drives... as >> >> >> >> >> >> demonstrated recently with my delay block? >> >> > >> >> >Been through some posts, but did not find it. Can you point me in the right direction? :-) >> >> > >> >> >Regards >> >> > >> >> >Klaus >> >> >> >> This is the way I generate precise delays (on-chip)... >> >> >> >> http://www.analog-innovations.com/SED/DelayCircuitForNarrowPulseWidths.pdf >> >> >> >> This delayed signal is then used to create non-overlapping drives for >> >> such things as full-H bridges, and commutating switches used in >> >> synchronous rectification and integrate control loops. >> >> >> >> Analysis is left as an exercise for the student ;-) >> >> >> >> Hints: >> >> >> >> (1) These are 10ps inverters (TSMC 0.18u process) >> >> (2) This is internal to a monolithic chip, so no ESD to get in your >> >> way, so left end of the cap flys above VDDD and below GNDD without >> >> clamping or consequence. >> >> >> >> This snap-shot is from a chip I designed last fall when I did an >> >> extended stay (:-) on Long Island and met Martin Riddle. >> >> >> >> Designed entirely on my laptop, the chip worked perfectly to >> >> specifications first pass thru the foundry, as do ALL of my designs... >> >> I never do "designs" without component values >:-) >> >> >> >> Klaus, I'll see if I can excise a clip showing how it inputs into the >> >> H-bridge without breaking any NDA restrictions. >> >> >> >> Is your posted E-mail address valid? >> > >Hi Jim > >Thank you for taking time to elaborate on this ;-) > >The email is: > >klauskvik@hotmail.com > >It is valid and hotmail spamfilter works, I hardly get spam any more... > >Regards > >Klaus
I have E-mailed you a full copy of my chip design. Observe rules noted to descend/ascend hierarchy. You can observe games I played to get 500mA full-H without crowbar. Do not share... some here are intellectual thieves and pretenders to being "designers" ;-) I did this whole thing on my Lenovo X61s. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Mon, 01 Oct 2012 12:35:52 -0600, hamilton <hamilton@nothere.com>
wrote:

>On 10/1/2012 11:46 AM, John Larkin wrote: >> On Mon, 01 Oct 2012 10:42:16 -0700, Jim Thompson >>> >>> How about a 6-pack of '04's paralleled? >>> >>> ...Jim Thompson >> >> Massive shoot-through. >> >> > >Please describe shoot-through. >
If a CMOS gate's input is roughly midway between Vcc and ground, both p-channel and n-channel fets can be partially turned on in the front end. Current "shots through" the fets from Vcc to ground. That can draw a lot of supply current and potentially heat up the chip. It always happens briefly when a normal, fast input transitions, but it can get much worse if an input transitions slowly, or parks at an intermediate voltage. Schmitt-trigger gates are designed for slow inputs, so generally have moderate peak shoot-through currents. Paralleling Schmitts is interesting. At some input voltage, some of the gates will see a "1" and some may see a "0", so their paralleled outputs will fight one another and pull a *lot* of supply current. Running the signal through one Schmitt section, and then driving a bunch more sections in parallel, is safer. We almost fried some Tiny Logic gates, powering them from +5 but driving them from 3.3 volt logic from an FPGA. They got really hot. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On Mon, 1 Oct 2012 12:46:54 -0700 (PDT), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

>On Monday, October 1, 2012 7:44:52 PM UTC+2, John Larkin wrote: >> On Mon, 1 Oct 2012 10:33:00 -0700 (PDT), Klaus Kragelund >> >> <klauskvikyhyy@hotmail.com> wrote: >> >> >> >> >Hi >> >> > >> >> >I need a CMOS gate with low voltage drop at about 30mA current source and sink. The tiny logic NL27WZ14 has 600mV drop at 32mA which equates to 18ohm RDS on. >> >> > >> >> >I am searching for a device with less than 5-10 ohms and it would need to be ok to parallel to get lower resistance. Also, it must not have to much crossover shoot-through (so probably schmitt trigger type) and must have low dissipation at high operational frequency (1-10MHz) >> >> > >> >> >Any one have a part in mind? >> >> > >> >> >Thanks >> >> > >> >> >Klaus >> >> >> >> Use something like an HC14, with one section buffering the input, then >> >> driving several other sections, up to 5, in parallel. >> >> >> >> More extreme on speed - sub ns edges - would be an NL37WZ17US, again >> >> with one section buffering the input to drive the other two. > >I found maybe a slightly better one, the NC7SZ14. The device lists CPD of 24 (Power dissipation capacitance, but no information on the unit. Icc = Cpd * V * f. > >(page 5 of http://www.fairchildsemi.com/ds/NC/NC7SZ14.pdf) > >I guess it's in pC (pico coloumb), which corresponds to 100uA/MHz. > >Regards > >Klaus
As Fred notes, CPD is equivalent picofarads. But it only applies for fast input transitions. I'm not sure if you are concerned about slow input edges. Wimpier logic families (slower, weaker current drive) tend to have lower equivalent CPDs. The WZ parts are fierce. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On Mon, 01 Oct 2012 21:39:48 +0200, Fred Bartoli <" "> wrote:

>Klaus Kragelund a &#2013265929;crit : >> Hi >> >> I need a CMOS gate with low voltage drop at about 30mA current source and sink. The tiny logic NL27WZ14 has 600mV drop at 32mA which equates to 18ohm RDS on. >> >> I am searching for a device with less than 5-10 ohms and it would need to be ok to parallel to get lower resistance. Also, it must not have to much crossover shoot-through (so probably schmitt trigger type) and must have low dissipation at high operational frequency (1-10MHz) >> >> Any one have a part in mind? >> >> Thanks >> >> Klaus > >Mucho thanks for posting this... > >In an attempt to answer I had a look at a recent design and noticed that >a 5V powered LVC14 escaped all the design reviews :-( > >It survived all the stress test: 27MHz switching, with PCB temp=100&#2013266096;C >while driving a 250pF Ciss Mosfet... > >How did you know ?-)
Abs max Vcc is 6.5. What's your problem? -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On Mon, 1 Oct 2012 16:49:41 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:

>On Oct 1, 1:33&#2013266080;pm, Klaus Kragelund <klausk...@hotmail.com> wrote: >> Hi >> >> I need a CMOS gate with low voltage drop at about 30mA current source and sink. The tiny logic NL27WZ14 has 600mV drop at 32mA which equates to 18ohm RDS on. >> >> I am searching for a device with less than 5-10 ohms and it would need to be ok to parallel to get lower resistance. Also, it must not have to much crossover shoot-through (so probably schmitt trigger type) and must have low dissipation at high operational frequency (1-10MHz) >> >> Any one have a part in mind? >> >> Thanks >> >> Klaus > >http://www.intersil.com/en/products/switches-muxs-crosspoints/low-voltage-switches/switches-muxs-crosspoints/ISL43L210.html > >(from John Devereux, earlier this year) > >Break-before-make. > >DigiKey had competing parts, too.
But look at the capacitances! There's no free lunch. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
John Larkin wrote:

> On Mon, 1 Oct 2012 16:49:41 -0700 (PDT), dagmargoodboat@yahoo.com > wrote: > > >>On Oct 1, 1:33 pm, Klaus Kragelund <klausk...@hotmail.com> wrote: >> >>>Hi >>> >>>I need a CMOS gate with low voltage drop at about 30mA current source and sink. The tiny logic NL27WZ14 has 600mV drop at 32mA which equates to 18ohm RDS on. >>> >>>I am searching for a device with less than 5-10 ohms and it would need to be ok to parallel to get lower resistance. Also, it must not have to much crossover shoot-through (so probably schmitt trigger type) and must have low dissipation at high operational frequency (1-10MHz) >>> >>>Any one have a part in mind? >>> >>>Thanks >>> >>>Klaus >> >>http://www.intersil.com/en/products/switches-muxs-crosspoints/low-voltage-switches/switches-muxs-crosspoints/ISL43L210.html >> >>(from John Devereux, earlier this year) >> >>Break-before-make. >> >>DigiKey had competing parts, too. > > > But look at the capacitances! There's no free lunch. > >
Talking about Digikey, they getting any better at stocking more of what they advertise? I have been leaning towards the other parts suppliers lately.. Jamie
"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message 
news:n5bk68h59kckkcmb8ntr5ecfauefjkmq6l@4ax.com...

> If a CMOS gate's input is roughly midway between Vcc and ground, both > p-channel and n-channel fets can be partially turned on in the front > end.
This problem is greatly overstated. While ago I tested static cross conduction of HCT04 gate powered at +5V. The worst case was about 4mA, at 0.9V at the input. Vladimir Vassilevsky DSP and Mixed Signal Consultant www.abvolt.com
On Mon, 01 Oct 2012 21:10:16 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

>John Larkin wrote: > >> On Mon, 1 Oct 2012 16:49:41 -0700 (PDT), dagmargoodboat@yahoo.com >> wrote: >> >> >>>On Oct 1, 1:33 pm, Klaus Kragelund <klausk...@hotmail.com> wrote: >>> >>>>Hi >>>> >>>>I need a CMOS gate with low voltage drop at about 30mA current source and sink. The tiny logic NL27WZ14 has 600mV drop at 32mA which equates to 18ohm RDS on. >>>> >>>>I am searching for a device with less than 5-10 ohms and it would need to be ok to parallel to get lower resistance. Also, it must not have to much crossover shoot-through (so probably schmitt trigger type) and must have low dissipation at high operational frequency (1-10MHz) >>>> >>>>Any one have a part in mind? >>>> >>>>Thanks >>>> >>>>Klaus >>> >>>http://www.intersil.com/en/products/switches-muxs-crosspoints/low-voltage-switches/switches-muxs-crosspoints/ISL43L210.html >>> >>>(from John Devereux, earlier this year) >>> >>>Break-before-make. >>> >>>DigiKey had competing parts, too. >> >> >> But look at the capacitances! There's no free lunch. >> >> > Talking about Digikey, they getting any better at stocking more of what >they advertise? I have been leaning towards the other parts suppliers >lately.. > >Jamie
Worse. Some searches get below 10% in-stock. Many times a search will bring up parts that simply can't be had, ever. Why do they do that? Another weirdness: expensive parts are available, and reasonably-priced parts aren't. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators