I need to level shift from 3.3V to 12V one way. ICC and IDD need to be less than 500uA combined, which is where the 4504 parts fail.
It doesn't need to be fast or stiff. I'm trying to aviod using a discrete solution if possible.
thanks.
While I haven't looked at the datasheets, I suspect you can achieve what you want with one of the RS232 driver charge pump type parts.
I;ve look at a few and the quiescent current is a too high. I can supply both rails 3.3 and 12V i just need something that can level shift beteen the two while comsuming very little quiescent current in the high or low state. that dictates CMOS.
Maybe a low quiescent mosfet mosfet driver that can pull this off?
"Mook Johnson" schrieb im Newsbeitrag news:45c2a2fa$0$4916$ snipped-for-privacy@roadrunner.com... | I;ve look at a few and the quiescent current is a too high. I can supply | both rails 3.3 and 12V i just need something that can level shift beteen the | two while comsuming very little quiescent current in the high or low state. | that dictates CMOS. | | Maybe a low quiescent mosfet mosfet driver that can pull this off?
And where is the problem to use a small MOSFET ?
- Henry
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"Henry Kiefer" wrote in news:45ccd330$0$18847$ snipped-for-privacy@newsspool4.arcor-online.net:
Good question. I realised Mook Johnson already asked, in a different thread (Subject: small 3.3V to 12V level shifter), but never said why it won't do. I'd mentioned a JFET idea I found once, an n-channel JFET, gate to common ground, pull-up resistor on the drain to 12V, input to the source, input being anything over 1 to 2V. I saw no feedback, just an eventual rephrasing of the same question in a new thread. With no dialog, there is no discussion. More people might pitch in if they knew what the poster was trying to do. Without that info all we can do is ask why the simple answer isn't good.
I thought maybe the pullup resistor might be the sticking point, having a higher current draw at all times than was wanted, but I couldn't think of a better idea so I said nothing this time till now. I still think it's viable, you can just set the resistor to the highest value that will work. It might work with over a megohm if the input resistance of the next logic stage is very high.
"Lostgallifreyan" schrieb im Newsbeitrag news:Xns98D2CEE006AABzoodlewurdle@140.99.99.130... [...]
OK. I will never respond.
- Henry
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"Henry Kiefer" wrote in news:45cd0ab3$0$5720$ snipped-for-privacy@newsspool3.arcor-online.net:
Never, is a VERY long time. :)
"Lostgallifreyan" schrieb im Newsbeitrag news:Xns98D36C439321zoodlewurdle@140.99.99.130... | "Henry Kiefer" wrote in | news:45cd0ab3$0$5720$ snipped-for-privacy@newsspool3.arcor-online.net: | | > OK. I will never respond. | >
| | Never, is a VERY long time. :)
Estimated by statistics: 50 years for me.
- Henry
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Sorry guys I've been out of the loop for a while.
Yeah the pull up is a problem. I only have 1 mA to work with for this part of the circuit. All I need to do ia turn on the gete of a large power mosfet but it doesn't need to happen quickly. I'm feeding the gate with a large resistor to limit the VGS capacitive charging current.
When the 3.3V input is high or low I need something that will latch the output high or low. The functionality of the 4504 is ideal I just need lower current draw.
"Mook Johnson" schrieb im Newsbeitrag news:45cd216a$0$16959$ snipped-for-privacy@roadrunner.com...
Depends on manufacturer: Have a look at ON Semi: http://www.ortodoxism.ro/datasheets2/d/0j47gl7pqooqcpgslej2uh9zs8ky.pdf
- Henry
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