ULN2803 ok to be driven by 3.3V logic?
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From: Joerg on 7 Jan 2010 16:20 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 http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 7 Jan 2010 17:09 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. I don't keep track of off-the-shelf stuff. Have you looked at open-drain buffers/inverters? ...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.
From: Joerg on 7 Jan 2010 17:27 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. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 7 Jan 2010 17:41 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? I'm working with an entrepreneur... sold his last company and is looking at new ventures, new parts. We just spun a specialty part aimed at surveillance camera controls. We'll take a look at the relay/low-side/high-side market and see what looks realistic. Don't be surprised if you get a call from Kiwi Semiconductors ;-) ...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.
From: Joerg on 7 Jan 2010 17:59
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? > 30c/1k, about 15c/100k, 30V, 300mA but that will be bond wire limited for the total. _Absolutely_ crucial: Industry standard pinout so it can be a drop-in for the ULN2803. Non-standard might work but only if your entrepreneur owns a company the size of Texas Instruments ;-) > I'm working with an entrepreneur... sold his last company and is > looking at new ventures, new parts. > > We just spun a specialty part aimed at surveillance camera controls. > Oooh, big brother ... Should be a good market in the UK, they seem to have every single pine cone under 24/7 surveillance. > We'll take a look at the relay/low-side/high-side market and see what > looks realistic. > > Don't be surprised if you get a call from Kiwi Semiconductors ;-) > Anytime. But I am usually more into fast stuff when it comes to power drivers. Injectors, transducers, pulsers et cetera. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |