ULN2803 ok to be driven by 3.3V logic?
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From: Joerg on 7 Jan 2010 19:15 Jim Thompson wrote: > On Thu, 07 Jan 2010 14:27:59 -0800, Joerg <invalid(a)invalid.invalid> > wrote: > >> Jim Thompson wrote: >>> On Thu, 07 Jan 2010 13:20:52 -0800, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> Gents, >>>> >>>> Have to drive a bucket full of 12V relays but the uC is only 3.3V. The >>>> ULN2803 is touted as a driver for 5V TTL logic by most companies (like >>>> TI) but datasheets hint that it can happily live down to around 3V drive >>>> level. Is that kosher? >>>> >>>> http://focus.ti.com/lit/ds/symlink/uln2803a.pdf >>>> http://www.toshiba.com/taec/components2/Datasheet_Sync//393/22738.pdf >>>> >>>> App note SLAA148 suggests it is kosher but ... I figure I'd better ask >>>> the famous gurus in this here group :-) >>> Should work just fine. >>> >>>> http://focus.ti.com/lit/an/slaa148/slaa148.pdf >>>> >>>> A FET version would be nice as it gets the outputs lower but that's only >>>> available from the more boutiquish suppliers. Demasiados Dolares, as usual. >>> I'm quite surprised there isn't a MOS version. >>> >> So am I. There are some but with boutique pricing. Not surprisingly many >> of them didn't make it in the marketplace because guys like me wouldn't >> use them. Here is a decoder type which can be used in "memory mode", and >> it also went to lalaland: >> >> http://www.allegromicro.com/en/Products/Part_Numbers/6259/6259.pdf >> >> >>> I don't keep track of off-the-shelf stuff. Have you looked at >>> open-drain buffers/inverters? >>> >> Yeah, they are either too wimpy or way more expensive than two dozen >> discrete parts. This time I need to drive relays with up to 60mA coil >> current each. > > A devious loaded question... What would you consider a reasonable > price for such a device? Max output voltage? Max output load > current? > P.S.: If you guys are eyeing the automotive and aerospace markets as well it needs to be at least 60V. I prefer 100V parts there, but you know automotive quite well. Avoids having to place a surge cutter. And don't forget them thar catch diodes. [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 7 Jan 2010 19:26 On Thu, 07 Jan 2010 14:27:59 -0800, Joerg <invalid(a)invalid.invalid> wrote: >Jim Thompson wrote: >> On Thu, 07 Jan 2010 13:20:52 -0800, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> Gents, >>> >>> Have to drive a bucket full of 12V relays but the uC is only 3.3V. The >>> ULN2803 is touted as a driver for 5V TTL logic by most companies (like >>> TI) but datasheets hint that it can happily live down to around 3V drive >>> level. Is that kosher? >>> >>> http://focus.ti.com/lit/ds/symlink/uln2803a.pdf >>> http://www.toshiba.com/taec/components2/Datasheet_Sync//393/22738.pdf >>> >>> App note SLAA148 suggests it is kosher but ... I figure I'd better ask >>> the famous gurus in this here group :-) >> >> Should work just fine. >> >>> http://focus.ti.com/lit/an/slaa148/slaa148.pdf >>> >>> A FET version would be nice as it gets the outputs lower but that's only >>> available from the more boutiquish suppliers. Demasiados Dolares, as usual. >> >> I'm quite surprised there isn't a MOS version. >> > >So am I. There are some but with boutique pricing. Not surprisingly many >of them didn't make it in the marketplace because guys like me wouldn't >use them. Here is a decoder type which can be used in "memory mode", and >it also went to lalaland: > >http://www.allegromicro.com/en/Products/Part_Numbers/6259/6259.pdf > > >> I don't keep track of off-the-shelf stuff. Have you looked at >> open-drain buffers/inverters? >> > >Yeah, they are either too wimpy or way more expensive than two dozen >discrete parts. This time I need to drive relays with up to 60mA coil >current each. TPIC6595 is cool, serial in and eight fet drains out, but it needs 5 volts. We're using them to drive a lot of relays. John
From: Joerg on 7 Jan 2010 19:40 John Larkin wrote: > On Thu, 07 Jan 2010 14:27:59 -0800, Joerg <invalid(a)invalid.invalid> > wrote: > >> Jim Thompson wrote: >>> On Thu, 07 Jan 2010 13:20:52 -0800, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> Gents, >>>> >>>> Have to drive a bucket full of 12V relays but the uC is only 3.3V. The >>>> ULN2803 is touted as a driver for 5V TTL logic by most companies (like >>>> TI) but datasheets hint that it can happily live down to around 3V drive >>>> level. Is that kosher? >>>> >>>> http://focus.ti.com/lit/ds/symlink/uln2803a.pdf >>>> http://www.toshiba.com/taec/components2/Datasheet_Sync//393/22738.pdf >>>> >>>> App note SLAA148 suggests it is kosher but ... I figure I'd better ask >>>> the famous gurus in this here group :-) >>> Should work just fine. >>> >>>> http://focus.ti.com/lit/an/slaa148/slaa148.pdf >>>> >>>> A FET version would be nice as it gets the outputs lower but that's only >>>> available from the more boutiquish suppliers. Demasiados Dolares, as usual. >>> I'm quite surprised there isn't a MOS version. >>> >> So am I. There are some but with boutique pricing. Not surprisingly many >> of them didn't make it in the marketplace because guys like me wouldn't >> use them. Here is a decoder type which can be used in "memory mode", and >> it also went to lalaland: >> >> http://www.allegromicro.com/en/Products/Part_Numbers/6259/6259.pdf >> >> >>> I don't keep track of off-the-shelf stuff. Have you looked at >>> open-drain buffers/inverters? >>> >> Yeah, they are either too wimpy or way more expensive than two dozen >> discrete parts. This time I need to drive relays with up to 60mA coil >> current each. > > TPIC6595 is cool, serial in and eight fet drains out, but it needs 5 > volts. We're using them to drive a lot of relays. > A buck fifty wouldn't fly in this case, serial would work well though. However, I have (almost) been burned by TPIC parts in the past, by part obsolescence. Somehow I had a hunch and chickened out. Now I am glad I did. But this one is cool if you have the budget and it's been around for almost two decades. If anyone is interested: http://focus.ti.com/lit/ds/symlink/tpic6595.pdf -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joe G (Home) on 8 Jan 2010 02:36 "Joerg" <invalid(a)invalid.invalid> wrote in message news:7qn1htFchdU1(a)mid.individual.net... > Gents, > > Have to drive a bucket full of 12V relays but the uC is only 3.3V. The > ULN2803 is touted as a driver for 5V TTL logic by most companies (like TI) > but datasheets hint that it can happily live down to around 3V drive > level. Is that kosher? > > http://focus.ti.com/lit/ds/symlink/uln2803a.pdf > http://www.toshiba.com/taec/components2/Datasheet_Sync//393/22738.pdf > > App note SLAA148 suggests it is kosher but ... I figure I'd better ask the > famous gurus in this here group :-) > > http://focus.ti.com/lit/an/slaa148/slaa148.pdf > > A FET version would be nice as it gets the outputs lower but that's only > available from the more boutiquish suppliers. Demasiados Dolares, as > usual. > > -- > Regards, Joerg > Infineon SPIDER Driver IC's - Multi channel SPI Driver? See here http://bit.ly/5xVmH8 Parallel and Serial Isolated ISOFACE Driver? http://bit.ly/5GrCFF Joe
From: Joerg on 8 Jan 2010 13:34
Joe G (Home) wrote: > "Joerg" <invalid(a)invalid.invalid> wrote in message > news:7qn1htFchdU1(a)mid.individual.net... >> Gents, >> >> Have to drive a bucket full of 12V relays but the uC is only 3.3V. The >> ULN2803 is touted as a driver for 5V TTL logic by most companies (like TI) >> but datasheets hint that it can happily live down to around 3V drive >> level. Is that kosher? >> >> http://focus.ti.com/lit/ds/symlink/uln2803a.pdf >> http://www.toshiba.com/taec/components2/Datasheet_Sync//393/22738.pdf >> >> App note SLAA148 suggests it is kosher but ... I figure I'd better ask the >> famous gurus in this here group :-) >> >> http://focus.ti.com/lit/an/slaa148/slaa148.pdf >> >> A FET version would be nice as it gets the outputs lower but that's only >> available from the more boutiquish suppliers. Demasiados Dolares, as >> usual. >> >> -- >> Regards, Joerg >> > Infineon SPIDER Driver IC's - Multi channel SPI Driver? > > See here http://bit.ly/5xVmH8 > Thanks. However, it costs almost two bucks in qties and Digikey has no stock (which is always a red flag for me). Yikes. That's almost ten times the cost of the ULN parts, not a chance. What were they thinking? > Parallel and Serial Isolated ISOFACE Driver? > http://bit.ly/5GrCFF > Those are very nice indeed when you need isolation (I often do). But also non-stock and they'd have to compete with the usual optocoupler plus driver solution. Considering that they want $6 for them that'll be a tall order for their sales guys. I wish Infineon would come off their key account thinking and stuff the channels, such as Digikey. And adjust their pricing. Their R&D develops top notch products but I often shun them because of past purchasing problems. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |