David Brown <david@westcontrol.removethisbit.com> writes:> On 19/03/13 10:25, John Devereux wrote: >> Arlet Ottens <usenet+5@c-scape.nl> writes: >> >>> On 03/19/2013 09:56 AM, David Brown wrote: >>> >>>> once case I wanted a serial-in, parallel-out latch. The 74HC595 is >>>> functionally ideal - except that at 5V supply it needs 3.5V for input >>>> high. A 74HCT595 would be possible, but it doesn't exist. >>> >>> Here you go. 74HCT595. Vih <= 2.0V. >>> >>> http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf >> >> Yes, don't seem to be too hard to get hold of! >> >> <http://octopart.com/partsearch#search/requestData&q=74hct595> >> >> Perhaps David was thinking of something else... >> > > It's certainly possible that I was thinking about something else - it > was a while ago when I worked on the project that needed such chips. > (And of course it is too late now - the board was completed using level > converters as well as the logic chips.) > > However, looking at the nxp data sheet I see that the HCT version needs > 3.15V at 4.5V - and presumably therefore 3.5V and 5V for its inputs. In > other words, it is useless for driving with 3.3V supplies. It seems > that in this respect nxp's HCT family are different from TI's HCT family > (which is the ones I originally looked at).Well I confess I didn't actually bother to look at any datasheets originally - why check anything before posting to the entire world, to be indexed and archived for eternity? But I think you are looking at the HC bit of the datasheet; HCT is 2.0V worst case AFAICS. <http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf>> Maybe there is a 74x595 out there somewhere which will work properly > from 3.3V inputs and 5V supplies, but I still haven't found it.-- John Devereux
Market size of new, non-legacy, 5V ICs ?
Started by ●March 17, 2013
Reply by ●March 19, 20132013-03-19
Reply by ●March 19, 20132013-03-19
In comp.arch.embedded, David Brown <david@westcontrol.removethisbit.com> wrote:> On 19/03/13 10:25, John Devereux wrote: >> Arlet Ottens <usenet+5@c-scape.nl> writes: >> >>> On 03/19/2013 09:56 AM, David Brown wrote: >>> >>>> once case I wanted a serial-in, parallel-out latch. The 74HC595 is >>>> functionally ideal - except that at 5V supply it needs 3.5V for input >>>> high. A 74HCT595 would be possible, but it doesn't exist. >>> >>> Here you go. 74HCT595. Vih <= 2.0V. >>> >>> http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf >> >> Yes, don't seem to be too hard to get hold of! >> >> <http://octopart.com/partsearch#search/requestData&q=74hct595> >> >> Perhaps David was thinking of something else... >> > > It's certainly possible that I was thinking about something else - it > was a while ago when I worked on the project that needed such chips. > (And of course it is too late now - the board was completed using level > converters as well as the logic chips.) > > However, looking at the nxp data sheet I see that the HCT version needs > 3.15V at 4.5V - and presumably therefore 3.5V and 5V for its inputs. In > other words, it is useless for driving with 3.3V supplies. It seems > that in this respect nxp's HCT family are different from TI's HCT family > (which is the ones I originally looked at).You are looking at the wrong data, go to page 8 of that datasheet, halfway there is a blue header '74HCT595'. The bottom half of page 8 gives the HCT specs: Vih=2.0V (min) Vil=0.8V (max) It wouldn't be 'TTL compatible' with Vih=3.15V.> Maybe there is a 74x595 out there somewhere which will work properly > from 3.3V inputs and 5V supplies, but I still haven't found it.Now you have. -- Stef (remove caps, dashes and .invalid from e-mail address to reply by mail) Love means nothing to a tennis player.
Reply by ●March 19, 20132013-03-19
On 2013-03-18, j.m.granville@gmail.com <j.m.granville@gmail.com> wrote:> On Sunday, March 17, 2013 10:35:28 PM UTC+12, Simon Clubley wrote: >> To my mind, it >> would be like Microchip, say, suddenly deciding to create a PIC32 range >> which runs at 5V. > > If you think that is 'strange' then perhaps I should not mention > the new Infieon, 32 bit XMC1000, that operates 1.8-5.5V ?? > > http://www.infineon.com/cms/en/corporate/press/news/releases/2013/INFATV201301-022.html > > Or mention Fujistu, or Nuvoton, who also offer 5V, 32 bit parts ?? >Thanks. That's a nice trend which I hope continues. Is there any similar move on the peripheral side of things ? The thing which finally forced me to start moving to 3.3V was trying to interface to one too many sensors/LCD displays/SPI devices which were 3.3V only and are not 5V tolerant. One of those SPI devices was Microchip's SPI RAM range, so that's why this new 5V capable series was such a surprise. Simon. -- Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP Microsoft: Bringing you 1980s technology to a 21st century world
Reply by ●March 19, 20132013-03-19
On 19/03/13 13:32, John Devereux wrote:> David Brown <david@westcontrol.removethisbit.com> writes: > >> On 19/03/13 10:25, John Devereux wrote: >>> Arlet Ottens <usenet+5@c-scape.nl> writes: >>> >>>> On 03/19/2013 09:56 AM, David Brown wrote: >>>> >>>>> once case I wanted a serial-in, parallel-out latch. The 74HC595 is >>>>> functionally ideal - except that at 5V supply it needs 3.5V for input >>>>> high. A 74HCT595 would be possible, but it doesn't exist. >>>> >>>> Here you go. 74HCT595. Vih <= 2.0V. >>>> >>>> http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf >>> >>> Yes, don't seem to be too hard to get hold of! >>> >>> <http://octopart.com/partsearch#search/requestData&q=74hct595> >>> >>> Perhaps David was thinking of something else... >>> >> >> It's certainly possible that I was thinking about something else - it >> was a while ago when I worked on the project that needed such chips. >> (And of course it is too late now - the board was completed using level >> converters as well as the logic chips.) >> >> However, looking at the nxp data sheet I see that the HCT version needs >> 3.15V at 4.5V - and presumably therefore 3.5V and 5V for its inputs. In >> other words, it is useless for driving with 3.3V supplies. It seems >> that in this respect nxp's HCT family are different from TI's HCT family >> (which is the ones I originally looked at). > > Well I confess I didn't actually bother to look at any datasheets > originally - why check anything before posting to the entire world, to > be indexed and archived for eternity? >Good question!> But I think you are looking at the HC bit of the datasheet; HCT is 2.0V > worst case AFAICS.I was indeed looking at the wrong part - I had mentally copied the table headers from "Recommended operating conditions" on page 7 onto the table below for the HC part rather than the temperature ranges.> > <http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf> > >> Maybe there is a 74x595 out there somewhere which will work properly >> from 3.3V inputs and 5V supplies, but I still haven't found it. >As you and Stef pointed out, now I have found such a part. I am pretty sure we looked at NXP (along with TI) when we were doing the project - I wonder why we didn't use it. (Even if I can't read datasheets properly, the others on the team would have read them too.) At least if we ever do another revision of the card, we can consider this chip. David
Reply by ●March 19, 20132013-03-19
On 18 Mar., 14:47, Vladimir Vassilevsky <nos...@nowhere.com> wrote:> On 3/18/2013 3:46 AM, Stef wrote: > > > For 3.3V to 5V we often use 74HCT. I always check the datasheets, and I > > can't remember a case where the levels did not work out, even in the > > extreme temperature specs. > > You certainly can use HCT, and it would work for 3.3V to 5V conversion. > However keep in mind that the quiescent current in "1" state is going to > be about 1mA per gate. >it varies alot nxp datasheet for 74hct14 says max 147uA at Vin = Vcc-2.1 ON semi say 2.4mA at Vin = 2.4V ! -Lasse
Reply by ●March 19, 20132013-03-19
On 3/19/2013 6:26 AM, David Brown wrote:> > It's certainly possible that I was thinking about something else - it > was a while ago when I worked on the project that needed such chips. > (And of course it is too late now - the board was completed using level > converters as well as the logic chips.) > > However, looking at the nxp data sheet I see that the HCT version needs > 3.15V at 4.5V - and presumably therefore 3.5V and 5V for its inputs. In > other words, it is useless for driving with 3.3V supplies. It seems > that in this respect nxp's HCT family are different from TI's HCT family > (which is the ones I originally looked at). > > Maybe there is a 74x595 out there somewhere which will work properly > from 3.3V inputs and 5V supplies, but I still haven't found it.In general you are right. I think the "logic" side of TTL is going away. The logic families seem to be primarily interface devices like buffers, tri-states and registers. What do you do that doesn't use PLDs of some type? -- Rick
Reply by ●March 20, 20132013-03-20
On 20/03/13 01:10, rickman wrote:> On 3/19/2013 6:26 AM, David Brown wrote: >> >> It's certainly possible that I was thinking about something else - it >> was a while ago when I worked on the project that needed such chips. >> (And of course it is too late now - the board was completed using level >> converters as well as the logic chips.) >> >> However, looking at the nxp data sheet I see that the HCT version needs >> 3.15V at 4.5V - and presumably therefore 3.5V and 5V for its inputs. In >> other words, it is useless for driving with 3.3V supplies. It seems >> that in this respect nxp's HCT family are different from TI's HCT family >> (which is the ones I originally looked at). >> >> Maybe there is a 74x595 out there somewhere which will work properly >> from 3.3V inputs and 5V supplies, but I still haven't found it. > > In general you are right. I think the "logic" side of TTL is going > away. The logic families seem to be primarily interface devices like > buffers, tri-states and registers. > > What do you do that doesn't use PLDs of some type? >This particular application needed to control a lot of solid-state relays from a 3.3V microcontroller. A chain of serial in, parallel out shift registers on the SPI bus is ideal for this - it's easy to control from the microcontroller, and there are only 4 wires routed around the board with each shift register connected to a group of 8 outputs. The shift registers are small, cheap and reliable. The only annoying issue is the levels, since the solid-state relays need 5V - we needed level converters too (though it is possible that the nxp 74HCT595 would have worked - I can't remember why we didn't use it). PLDs would be much more expensive, require programming (both development time and effort, and at production time we would need to burn in the program), require much more routing since it is centralised, and be less reliable (being more complex). And of course most PLDs are 3.3V maximum output, though they are generally very flexible about their inputs. If this had been a bunch of different logic chips connected together such as for address decoding, then I'd agree that a PLD would be a good plan.
Reply by ●March 20, 20132013-03-20
In article <Q6mdnXduwdLtoNXMnZ2dnUVZ8v2dnZ2d@lyse.net>, david@westcontrol.removethisbit.com says...> > On 19/03/13 10:25, John Devereux wrote: > > Arlet Ottens <usenet+5@c-scape.nl> writes: > > > >> On 03/19/2013 09:56 AM, David Brown wrote: > >> > >>> once case I wanted a serial-in, parallel-out latch. The 74HC595 is > >>> functionally ideal - except that at 5V supply it needs 3.5V for input > >>> high. A 74HCT595 would be possible, but it doesn't exist. > >> > >> Here you go. 74HCT595. Vih <= 2.0V. > >> > >> http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf > > > > Yes, don't seem to be too hard to get hold of! > > > > <http://octopart.com/partsearch#search/requestData&q=74hct595> > > > > Perhaps David was thinking of something else... > > > > It's certainly possible that I was thinking about something else - it > was a while ago when I worked on the project that needed such chips. > (And of course it is too late now - the board was completed using level > converters as well as the logic chips.) > > However, looking at the nxp data sheet I see that the HCT version needs > 3.15V at 4.5V - and presumably therefore 3.5V and 5V for its inputs. In > other words, it is useless for driving with 3.3V supplies. It seems > that in this respect nxp's HCT family are different from TI's HCT family > (which is the ones I originally looked at). > > Maybe there is a 74x595 out there somewhere which will work properly > from 3.3V inputs and 5V supplies, but I still haven't found it.Hmm wonders what is so difficult 74AHCT585 VIH min 2V @ Vcc = 4.5V 74AHC595 VIH min 2.1V @ Vcc = 3V VIH = 3.85 @ Vcc = 5V Actually seem to be OK for my uses anyway, plentiful available. -- Paul Carpenter | paul@pcserviceselectronics.co.uk <http://www.pcserviceselectronics.co.uk/> PC Services <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font <http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny <http://www.badweb.org.uk/> For those web sites you hate
Reply by ●March 20, 20132013-03-20
On 3/20/2013 4:08 AM, David Brown wrote:> On 20/03/13 01:10, rickman wrote: >> >> What do you do that doesn't use PLDs of some type? >> > > This particular application needed to control a lot of solid-state > relays from a 3.3V microcontroller. A chain of serial in, parallel out > shift registers on the SPI bus is ideal for this - it's easy to control > from the microcontroller, and there are only 4 wires routed around the > board with each shift register connected to a group of 8 outputs. The > shift registers are small, cheap and reliable. The only annoying issue > is the levels, since the solid-state relays need 5V - we needed level > converters too (though it is possible that the nxp 74HCT595 would have > worked - I can't remember why we didn't use it). > > PLDs would be much more expensive, require programming (both development > time and effort, and at production time we would need to burn in the > program), require much more routing since it is centralised, and be less > reliable (being more complex). And of course most PLDs are 3.3V maximum > output, though they are generally very flexible about their inputs. > > If this had been a bunch of different logic chips connected together > such as for address decoding, then I'd agree that a PLD would be a good > plan.Ok, that is exactly the sort of app that MSI was designed for. I agree an FPGA is more than you need, although I won't agree that it is *more* expensive. I'm not sure what they are charging for 595 chips these days, but most of this stuff is $0.25 or more. That's about parity for 8 of these and a 100 pin FPGA. Well, maybe the FPGA is a bit more at $3-$4, depends on quantity. The main limitation is the I/O voltage. I have not found an FPGA tolerant of 5 volt signals. I had to add two 24 pin Quickswitch parts as buffers to a design I did a while back. FPGA folks just don't feel there is market enough to take the hit in whatever they would need to take the hit in for 5 volt tolerant I/Os. As to the programming in production, does that add much time or trouble? If your design is stable you can get Flash FPGAs or the Flash PROMs for regular FPGAs preprogrammed by your vendor. Once you add a bit of programmable logic to a board, it can be surprising what you find for it to do. -- Rick
Reply by ●March 21, 20132013-03-21
On 20/03/13 21:33, rickman wrote:> On 3/20/2013 4:08 AM, David Brown wrote: >> On 20/03/13 01:10, rickman wrote: >>> >>> What do you do that doesn't use PLDs of some type? >>> >> >> This particular application needed to control a lot of solid-state >> relays from a 3.3V microcontroller. A chain of serial in, parallel out >> shift registers on the SPI bus is ideal for this - it's easy to control >> from the microcontroller, and there are only 4 wires routed around the >> board with each shift register connected to a group of 8 outputs. The >> shift registers are small, cheap and reliable. The only annoying issue >> is the levels, since the solid-state relays need 5V - we needed level >> converters too (though it is possible that the nxp 74HCT595 would have >> worked - I can't remember why we didn't use it). >> >> PLDs would be much more expensive, require programming (both development >> time and effort, and at production time we would need to burn in the >> program), require much more routing since it is centralised, and be less >> reliable (being more complex). And of course most PLDs are 3.3V maximum >> output, though they are generally very flexible about their inputs. >> >> If this had been a bunch of different logic chips connected together >> such as for address decoding, then I'd agree that a PLD would be a good >> plan. > > Ok, that is exactly the sort of app that MSI was designed for. I agree > an FPGA is more than you need, although I won't agree that it is *more* > expensive. I'm not sure what they are charging for 595 chips these > days, but most of this stuff is $0.25 or more. That's about parity for > 8 of these and a 100 pin FPGA. Well, maybe the FPGA is a bit more at > $3-$4, depends on quantity. The main limitation is the I/O voltage. I > have not found an FPGA tolerant of 5 volt signals. I had to add two 24 > pin Quickswitch parts as buffers to a design I did a while back. FPGA > folks just don't feel there is market enough to take the hit in whatever > they would need to take the hit in for 5 volt tolerant I/Os. > > As to the programming in production, does that add much time or trouble? > If your design is stable you can get Flash FPGAs or the Flash PROMs for > regular FPGAs preprogrammed by your vendor. > > Once you add a bit of programmable logic to a board, it can be > surprising what you find for it to do. >Thanks for the recommendation here - and perhaps I will consider programmable logic a bit more favourably in the future (we /did/ consider it on this board too). But the key points against progammable logic here are that it means extra steps in development, extra steps in production, it clumps all the I/O together in one place rather than having a nice easily routeable chain of parts on an SPI bus, and it means using a complex part (with potential bugs) rather than a clear and simple "it just works" solution. Obviously there is lots more that can be done once you first have programmable logic on board. But the flexibility is not cost-free.