While e.g. TI explicitly mentions and specifies Input hysteresis for the SN74LS245, for newer families the keyword "hysteresis" is only mentioned for the real "schmitt-triggers" (14,17,132). The part with most gates in a package is the 74xx14 with 6 gates, however with a non-flow-through layout.
Do you know any good available 8/16/.. Bit wide logictranceiver with flow-through layout in a modern logicfamily like LVC?
Thanks
-- Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt --------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------
I just designed one in, 74LVC244:
The NXP datasheet explicitly states "Schmitt-trigger action at all inputs" while TI doesn't. So I had the unfortunate situation of releasing one mfg and not another. But don't expect much detail even from the NXP datasheet, it ain't like in them good old days no more.
Hey, my design-in rate for NXP now went from 0% to 0.1%! Despite the fact that they seem unable to design a good web site.
-- Regards, Joerg http://www.analogconsultants.com
Joerg wrote: ...
No specification about the hysteresis and no tranceiver, but thanks for the pointer (and I remember you mentioned the part in a similar thread that my search keywords didn't bring up...).
Bye
-- Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt --------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------
Well, I use it as a transceiver (back-to-back). It's fairly easy because they split them in half. As for the hysteresis, as I said, specsmanship ain't what it used to be. However, Philips always had excellent family specs so you might want to look those up. As long as NXP hasn't blown the access to that.
Chances are there may not be a Schmitt transceiver with layout-friendly pin-out and a defined hysteresis level. Or as they say in Germany you might have to bake one ;-)
-- Regards, Joerg http://www.analogconsultants.com
Joerg wrote: ...
I already considered to use the XC2C32A in 44-VQFP package. You can program the Input for 500mV Hysteresis, Bus-Hold, Pullup or none. At 1E@1 pieces comparable to a SN74LVC16245ADGGR at 0.91@1, disregarding the need for the
1.8 volt supply.At least module transceiver ( inout [15:0] busa, inout [15:0] busb, input dir ); assign busa = (dir)? busb: 16'bz; assign busb = (dir)? 16'bz: busa; endmodule
fits in the XC2c32a and implements a 16 bit transceiver with Direction input.
I wonder why so few modern logic series offer hysteresis as inputs option.
Cheers
-- Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt --------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------
That is what I have wondered about since the start of my career. I mean, it ain't rocket science to implement it. I was never fond of programmables. The first ones (PALs) were extremely inefficient when it came to power consumption while the newer ones are typically single-sourced and have rather short production life spans.
-- Regards, Joerg http://www.analogconsultants.com
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.