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simple voltage level shifter

E

exxos

Jan 1, 1970
0
HI all,

Have a small interface problem, easy cure would be to use a transistor to
switch the voltage levels though im wondering if there is a easier way (IE
less parts as im limited on space) drive voltage is 4volts, but I need to
boost that to 10V or more from a 15V supply rail..

I've been toying with a pullup and using a diode to pull the line down to
ground when the IC goes low, problem is when it goes high im forcing the 4V
line to 15volts which will probably blow the IC... can't think of any other
way apart from to use a small transistor ?

Cheers,
Chris
 
E

exxos

Jan 1, 1970
0
exxos said:
HI all,

Have a small interface problem, easy cure would be to use a transistor to
switch the voltage levels though im wondering if there is a easier way (IE
less parts as im limited on space) drive voltage is 4volts, but I need to
boost that to 10V or more from a 15V supply rail..

I've been toying with a pullup and using a diode to pull the line down to
ground when the IC goes low, problem is when it goes high im forcing the
4V line to 15volts which will probably blow the IC... can't think of any
other way apart from to use a small transistor ?

Cheers,
Chris


replying to my own post....

a 11V zener and resistor pullup should in theory do it I think, when the IC
is at 4V the zener will drop 11V so it will end up with 4V back on the
IC..... thinking of a form of shifter which will just drop to 8volts...
anything below 8V is considered low so might able to use that and just use a
4V switch to raise it to around 11V for my logic 1.... might work....

chris
 
C

CWatters

Jan 1, 1970
0
exxos said:
a 11V zener and resistor pullup should in theory do it I think, when the IC
is at 4V the zener will drop 11V so it will end up with 4V back on the
IC..... thinking of a form of shifter which will just drop to 8volts...
anything below 8V is considered low so might able to use that and just use a
4V switch to raise it to around 11V for my logic 1.... might work....

You can get some very small surface mount transistors that probably smaller
than a leaded zenner...

http://www.infineon.com/cmc_upload/documents/077/004/ApplicationNote_Version5.pdf

1mm x 0.6mm x 0.4mm

Just don't sneeze!
 
E

exxos

Jan 1, 1970
0
CWatters said:
You can get some very small surface mount transistors that probably
smaller
than a leaded zenner...

http://www.infineon.com/cmc_upload/documents/077/004/ApplicationNote_Version5.pdf

1mm x 0.6mm x 0.4mm

Just don't sneeze!

Yeah already possible, I don't seem to have a lot of luck with transistor
packages like that, resistors, capacitors, QSOP IC's all I can do fine,
though when it comes to 3 pin SMT transistors I can never seem to do those,
not to good when you have been replacing them for 10 years in SMPSU's either
;-)

*sneezes*



Bah!

Chris :)
 
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