Input I/O voltage for SPI flash - AT45DB321D?

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#1
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Hi, 

 

I am designing a PCB using the AT45DB321D FLASH. The controller I am using to connect it via SPI runs at 3.3V, so the SPI pins will be driven at 3.3V

Is it fine to use this IC at I/O voltage as 3.3V?

 

The datasheet says that the supply voltage can be between 2.7 to 3.5 V, but does not mention if the I/O voltage can be the same.

It only mentions that it is a 2.7V flash IC.

 

Please help in this regard.

 

Thanks. 

 

EDIT:  Link to Datasheet:  https://media.digikey.com/pdf/Da...

 

Jim

Last Edited: Wed. Jan 31, 2018 - 05:29 PM
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Whatever your Vcc is, that will also be your Vi/o as well.

 

 

 

 

See my next post.

JIm

If you want a career with a known path - become an undertaker. Dead people don't sue! - Kartman

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

Last Edited: Wed. Jan 31, 2018 - 05:34 PM
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AT45 has always been a 3.3V device hasn't it? Surely 2.7 to 3.5 is the guaranteed operational window but optimal withing that is 3.3V

 

(I imagine most "3.3V" chips specify a similar "acceptable range" too).

 

As a gross generalisation almost all systems/components are going to be one of 5V or 3.3V. AT45 falls into the latter.

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Thanks Jim.

 

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Cliff, from page 2 of teh datasheet:

The Atmel AT45DB321D is a 2.5V or 2.7V, serial interface, sequential access flash memory

 

 

But if you look at the electrical characteristics page :

 

It would appear that its a CMOS level so the datasheet is a little vague on page 2

 

Jim

If you want a career with a known path - become an undertaker. Dead people don't sue! - Kartman

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

Last Edited: Wed. Jan 31, 2018 - 05:35 PM
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But the very first bullet point on page 1 says:

● Single 2.5V - 3.6V or 2.7V - 3.6V supply

 

And, in the 2nd paragraph of p2:

 The device operates from a single power supply, 2.7V to 3.6V, for both the program and read operations. 

 

So it seem pretty clear that they are using "2.7V" as an abbreviation for "2.7V to 3.6V"; and "2.5V" as an abbreviation for "2.5V to 3.6V"

 

On p29, Table 16-1. DC and AC Operating Range, is pretty clear that they both go up to 3.6V

 

And Table 16-2. DC Characteristics, clearly shows that the IO voltages are relative to VCC

 

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Andy, 

If the operating voltage is between 2.5 and 3.6, then why write:

● Single 2.5V - 3.6V or 2.7V - 3.6V supply

to begin with?

 

 Or this too for that matter:

The Atmel AT45DB321D is a 2.5V or 2.7V, serial interface, sequential access flash memory

 

Since the DC characteristics clearly as noted in both yours and my posts that the I/O is relative to Vcc?

 

JIm 

If you want a career with a known path - become an undertaker. Dead people don't sue! - Kartman

Please Read: Code-of-Conduct

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Depends on:

David (aka frog_jr)

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#3

AT45 has always been a 3.3V device hasn't it?

 

No the first was 5V, (like those on the stk500) 

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jgmdesign wrote:
Andy, 

If the operating voltage is between 2.5 and 3.6, then why write:

● Single 2.5V - 3.6V or 2.7V - 3.6V supply

to begin with?

Yes, it does all seem to be rather poorly thought-through and inconsistent.

 

 

It looks like there are 2 versions of the chip:

  • The "standard" one does 2.7 - 3.6;
  • The "extended" one goes down to 2.5 (same top limit).

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awneil wrote:
It looks like there are 2 versions of the chip: The "standard" one does 2.7 - 3.6; The "extended" one goes down to 2.5 (same top limit).

 

Yeah, that was pointed out in post #9.  Based on the opening statement on Page 2 of the datasheet it would be a better read if it said there are two varieties blah blah blah as opposed to the current wording.

 

Oh well,

Jim 

If you want a career with a known path - become an undertaker. Dead people don't sue! - Kartman

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

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jgmdesign wrote:
it would be a better read if it said there are two varieties blah blah blah as opposed to the current wording.

Agreed.

 

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