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2.7 to 5V level shifting

R

Richard Hosking

Jan 1, 1970
0
Dear all
Looking for a simple way to interface 2.7V Flash Mmeory to a 5V uC.
The various peripherals in the system are 5V (LCD module, programming
interface, sensors) so it seems easiest to interface the memory. There
doesnt seem to be a serial flash available in 5V. Lots of parallel flash
devices at 5V but these are old and take too many lines

One line will have to be bidirectional

Thanks

Richard
 
L

Lionel

Jan 1, 1970
0
Dear all
Looking for a simple way to interface 2.7V Flash Mmeory to a 5V uC.
The various peripherals in the system are 5V (LCD module, programming
interface, sensors) so it seems easiest to interface the memory. There
doesnt seem to be a serial flash available in 5V. Lots of parallel flash
devices at 5V but these are old and take too many lines

One line will have to be bidirectional

There are plenty of multi-bit buffer that include level converters
that'll handle 2.7V to 5V.
How many bits do you need to convert to 5V?
 
E

Eeyore

Jan 1, 1970
0
Richard said:
Dear all
Looking for a simple way to interface 2.7V Flash Mmeory to a 5V uC.
The various peripherals in the system are 5V (LCD module, programming
interface, sensors) so it seems easiest to interface the memory. There
doesnt seem to be a serial flash available in 5V. Lots of parallel flash
devices at 5V but these are old and take too many lines

One line will have to be bidirectional

Will the 2.7V flash tolerate 5V I/O ? How about a part number ?

Graham
 
R

Robbo

Jan 1, 1970
0
Richard Hosking said:
Dear all
Looking for a simple way to interface 2.7V Flash Mmeory to a 5V uC.
The various peripherals in the system are 5V (LCD module, programming
interface, sensors) so it seems easiest to interface the memory. There
doesnt seem to be a serial flash available in 5V. Lots of parallel flash
devices at 5V but these are old and take too many lines

One line will have to be bidirectional

Thanks

Richard



Re the LCD module - it may be worth a second look at the data sheet. I'm
pretty sure that some have 3v compatible logic i/o despite the 5V supply.
 
E

Eeyore

Jan 1, 1970
0
Robbo said:
Re the LCD module - it may be worth a second look at the data sheet. I'm
pretty sure that some have 3v compatible logic i/o despite the 5V supply.

Also, since the display won't need any bidirectional lines it would be
relatively easy to use with mixed supplies anyway.

Graham
 
R

Richard Hosking

Jan 1, 1970
0
Atmel ATDB021B
These are easily available. I am basically a hobbyist. It is preferable
if the part is available from somewhere like Farnell

Richard
 
L

Lionel

Jan 1, 1970
0
Sorry AT45DB021B

Okay, here's the datasheet:
<http://www.atmel.com/dyn/resources/prod_documents/doc1937.pdf>

The memory chip has 2 outputs & 5 inputs.
It turns out that all the inputs are specified to be 5V tolerant, so
you can wire them directly to your 5V logic outputs.
And for your outputs, 2.7V is high enough that they should work fine
straight into single 5V inputs. Easy!

So, good news! - It looks like you won't need any level translation
electronics at all. Isn't it nice when things work out like that? ;^)

Best of luck with your project.
 
E

Eeyore

Jan 1, 1970
0
Richard said:
Atmel ATDB021B

I got the right part number.

These are easily available. I am basically a hobbyist. It is preferable
if the part is available from somewhere like Farnell

It looks from a brief glance at the data sheet that the inputs are 5V tolerant.
It might be a good idea to check that with Atmel to be confident.

In which case all you need to do is ensure that you uC will recognise its logic
1 output. That could be done with just a couple of resistors to help pull it up
a bit..

Graham
 
U

Uwe Bonnes

Jan 1, 1970
0
Richard Hosking said:
Dear all
Looking for a simple way to interface 2.7V Flash Mmeory to a 5V uC.
The various peripherals in the system are 5V (LCD module, programming
interface, sensors) so it seems easiest to interface the memory. There
doesnt seem to be a serial flash available in 5V. Lots of parallel flash
devices at 5V but these are old and take too many lines

SN74LVC8T245
 
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