Which one is correct?

[moparzrule]

Just looking into the 27c256 chips for making cal's, the Eprom's that are once and done no erase.

But Mouser supplies two of them, so which one is correct? The only difference I see is the access time, one is 45ns and one is 70ns. Since the 45ns is cheaper and obviously faster, I was gonna just go with that one unless it won't work. Anybody know?

45ns-
http://www.mouser.com/ProductDetail/...hpEAPCDtWXU%3d

70ns-
http://www.mouser.com/ProductDetail/...80jBz050W6M%3d

[TommyT]

bump.....I'd like to know too!

[moparzrule]

I'm pretty sure it's the 45ns, but I want to be positive.

[risen]

From the 2 minutes I spent looking at the datasheet all the address and i/o lines look like they line up and the only difference is the access time, so either should be OK. I would just order 1 and try it before spending a bunch of money on many chips.

[moparzrule]

The only difference I see is the access time

the only difference is the access time

Umm...thanks for the insight

[wowzer]

fwiw - i just bought a couple of the sst27sf512 chips from xenocron which seem to work great plus they are rewriteable.

http://www.xenocron.com/eprom-chip-s...gle-p-149.html

[wowzer]

fwiw - i just bought a couple of the sst27sf512 chips from xenocron which seem to work great plus they are rewriteable. just have to make sure you use an offset of 8000H

http://www.xenocron.com/eprom-chip-s...gle-p-149.html

[risen]

Umm...thanks for the insight

I confirmed what you previously thought. Also, I matched the address and i/o lines up to what our ecus need, that should be all that's needed as long as they're 120ns or under. If you already did that, you should have mentioned it. Now, did you want something more in depth than that? If so, please be a little more descriptive next time.

[moparzrule]

fwiw - i just bought a couple of the sst27sf512 chips from xenocron which seem to work great plus they are rewriteable. just have to make sure you use an offset of 8000H

http://www.xenocron.com/eprom-chip-s...gle-p-149.html

Yes I just bought a pack of 5 off them and got them the other day, but those are for myself. They also were NOT new chips, they were used. Every single one of them had data on them and needed erased, and only two of them seemed to want to erase. So yeah I got 3 dead chips out of 5.
I'm looking at getting the Eprom's for cal's for other people. This way they don't have to worry about shipping a chip back to me for a re-cal if needed, I'll just send them another one and it didn't cost as much.

[moparzrule]

I confirmed what you previously thought. Also, I matched the address and i/o lines up to what our ecus need, that should be all that's needed as long as they're 120ns or under. If you already did that, you should have mentioned it. Now, did you want something more in depth than that? If so, please be a little more descriptive next time.

I kinda figured that was assumed when I said the only difference I could find was the access time.
The highlighted portion is what I needed to know. But how did you come up with the 120ns figure?

[risen]

I kinda figured that was assumed when I said the only difference I could find was the access time.
The highlighted portion is what I needed to know. But how did you come up with the 120ns figure?

I'm not in the habit of assuming anything and I didn't think a question based solely upon the access time warranted a post. The maximum access time has been posted a couple of places. Basically, if a 90ns or 70ns chip works, anything faster will put the output lines up/down in the correct amount of time.

[moparzrule]

I'm not in the habit of assuming anything and I didn't think a question based solely upon the access time warranted a post. The maximum access time has been posted a couple of places. Basically, if a 90ns or 70ns chip works, anything faster will put the output lines up/down in the correct amount of time.

I've never seen anything about it posted.

Good to know. If you don't know you don't know. Apparently you know that faster access time doesn't screw anything up, I and probably many other people didn't know that.