Don't we all know that? "Hey, we need this new thingamagic that we saw at a competitor and it's going to be easy, I think ..."
Ah, so now you can be found every night for dinner in the Kaeferschaenke :-)
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Thanks. Looks like the LVC4245 which is probably what I am going to use.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
AFAIK those are only 5V-tolerant but can't really drive 5V logic with gusto on the other side.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Maybe I should have said "have you seen the prices Farnell charge for them ?". It may have improved since I last looked though.
Graham
something like this then
it has dual supply, one for each side
-Lasse
Yep, or the LVC4245 I wanted to use.
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...
...
I think they are trying to explain that if you are driving the enable from another device (not necessarily a 74LVC4245) you need to put a pull-down on the enable to guarantee that it remains low (and thus the
74LVC4245 remains in high-z) during power transitions. It is not related to any characteristic of the 74LVC4245 itself.kevin
Look at the I2C spec, they do this using mosfets and is bidir.
Don't know that but recently I designed in some 74LVXC3245, yet to power the first board with them, though. But I am pretty experienced with that sort of thing and did not smell anything foul (and I hope saying so now won't come and bite me in 2-3 weeks time when I have the prototype board here...).
Will do - but will take two chips if you need to simultaneously have both directions actively driven. The two sides are separately powered which should make sure no thermal issues like those John mentioned are to be expected.
You must have overlooked something there. OE should be an input only - must be held low for the drivers to be open - the drivers on the 16 data pins, that is. Drive it high and all get tristated.
Didi
------------------------------------------------------ Dimiter Popoff Transgalactic Instruments
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Original message:
It wasn't the LVC spec, that one is not stellar either but ok. Sometimes I wonder if anyone proof-reads these things. But I am not surprised. Right after getting my degree I met an alumni somewhere at an airport or railways station . He had received his masters about the same time but had never done any hobby projects, IOW his knowledge base was all from books and professors. "Hey, what are you doing these days?" ... "Hire on at a big semiconductor manufacturer" ... "What are you doing there?" ... "Writing application notes". I almost froze.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Is that why I2C hangs so often ... ?
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
If it's any comfort my design is also a white-knuckle ride. Lots of rather unorthodox high voltage stuff on there, all kinds of safety interlocks like HV only to come up when +5V is at least 4.5V but only when there is a full moon, and that sort of thing. Design -> layout -> production. No breadboarding at all.
Not quite. Quote "When the output-enable (OE) input is low, all outputs are placed in the high-impedance state. To ensure the high-impedance state during power up or power down, OE should be tied to GND through a pulldown resistor; the minimum value of the resistor is determined by the current-sourcing capability of the driver."
Low is tri-state. Then further down, quote: "The TXB0104 is designed so that the OE input circuit is supplied by VCCA."
Anyhow, that thing is too hokey for me. I kicked it out and replaced with LVC4245A, two of them. Now I found out that SOT23 LED have all but vanished. Darn ...
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
What's not to like about the 74LCX245?
...Jim Thompson
--
| James E.Thompson, P.E. | 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
Come to think of it, I have not used any breadboarding for my designs either last 20 years or so... I had stopped breadboarding for some time back then when SMT came in and made breadboarding impractical anyway :-).
Oh I thought you were referring to the x245, I just don't know that TXB0104 thing, my mistake.
Didi
------------------------------------------------------ Dimiter Popoff Transgalactic Instruments
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Original message:
Well, I am using the LVC4245 now. I like the two supplies on those, IOW a "real" level translator. Got to deal with power sequencing though.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
driver
T'other month did an 'Xport' network adaptor thing for a customer. I couldn't be arsed ordering or waiting for translator chips, so used a dozen transistors instead. But I wasn't looking for 1nS switching :). I'm happily using more and more of the these transistor things as time goes on, having had a belly full of I.C. stuff being obsoleted and the disruption it causes. Assembly cost of discretes would have been a problem 5 years ago but it's now all pick-n-place and I've yet to hear a peep of complaint from the production company. Ltspice to pick-n-place to customer. Ain't modern technology the bee's knees. Earning a crust is getting much, much easier :)
In sci.electronics.components Joerg wrote: ...
Nowerdays I use the 74LVC8T245 or 74LVC1|2T45 ..
-- Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt --------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------
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