ttl output to cmos input
ttl output to cmos input
(OP)
i need to input signal to a cmos device, but it is shielded and fed from 12vdc and have an internal regulator to 2.9vdc.
i have a 12vdc supply and a 5v regulator.
how to convert the 5vdc signal from mcu to input the device.
its input is very sensitive to overcharge so 3.3vdc would destroy it.
any tip any sug?
best
killa
i have a 12vdc supply and a 5v regulator.
how to convert the 5vdc signal from mcu to input the device.
its input is very sensitive to overcharge so 3.3vdc would destroy it.
any tip any sug?
best
killa





RE: ttl output to cmos input
RE: ttl output to cmos input
some day i read about problems involved with inappropiated level shifting.
thanks
killa
RE: ttl output to cmos input
and the highest data rate? I have to look up their data sheets.
<nbucska@pc33peripherals.com> omit 33 Use subj: ENG-TIPS
Plesae read FAQ240-1032
RE: ttl output to cmos input
RE: ttl output to cmos input
You might be able to use a single transistor to convert the logic 5v by driving the base with the logic (5v) then using the open collector with a resistor tied to the 12 or 5volt ps with a zener to set the 2.9volt level to the cmos.
-elf
RE: ttl output to cmos input
by the way this would be an inverted signal so if that;s a problem you might have to use a second transistor to get back to the original non inverted form.
-elf
RE: ttl output to cmos input
Another possibility might be to use a voltage divider network with maybe a 3.1V zener for protection only. The input impedance on CMOS inputs is very high so I would think that might work.
RE: ttl output to cmos input
usually converting from 5v ttl to 3 v cmos logic requires only a 10K series resistor if the cmos gate is diode protected (diode from gnd to input and diode prom input to 3v supply)
to achieve bidirectional comm, is common the use of logic level translators as found in maxim.com
thanks all for your valuable help
killa
RE: ttl output to cmos input