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Is there a 74HCT03 equivalent I can just replace "as is"? Of course, it will be better to buy the same exact chip reference but is it always the case?

Many chips are equivalents pin-to-pin, right? If so, (in limits of current & voltages of course)...is this possible in most cases or is this always a stupid idea?

Thanks.

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    \$\begingroup\$ I didn't get what equivalent do you mean? Why you cant buy the chip as is? \$\endgroup\$ – betontalpfa Nov 14 '18 at 12:36
  • \$\begingroup\$ it's just both a general question & applied to a current need :) in facts \$\endgroup\$ – francois P Nov 14 '18 at 17:46
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That completely depends on the circuitry. Both in terms of logic levels, signal delays, and transition speeds.

The 74HCTxxx logic family was precisely designed to be TTL-compatible high-speed CMOS. That is, fast and low-power like the 74HCxxx family but capable of accepting TTL-level outputs from the 74xxx and 74LSxxx families.

If the circuitry around it is 74HC or 74HCT, it is very likely that it can be substituted by a 74HC or faster component. If it is a different logic family, your mileage might vary.

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74HCT03 is still an active component, available for 0.5$ (USD), thru hole DIP and SMD packages available. Why not use the same part to ensure IO levels will be satisfied?

https://www.digikey.com/products/en?keywords=74hct03

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  • \$\begingroup\$ thanks. thanks you so I'll do a exact replacements for thoses low prices IC's \$\endgroup\$ – francois P Nov 14 '18 at 17:48
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Most Logic chips tend to have the same (or very similar) pinouts. You can have a look at other NAND gate chips (there are many out there) and as long as the pinout is the same and you can get them in the same package, then yes, you can simply replace it with any of them. It is not a stupid idea at all. I have had logic chips that I used but when trying to get more, my supplier was out of stock so I simply got a different one in the same package with the same pinout and just fitted that instead.

Do make sure that any IC you choose to fit has the correct ratings that you need, usually found in the electrical specifications section of the datasheets.

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  • \$\begingroup\$ thanks you so I'll do a exact replacements for thoses low prices IC's \$\endgroup\$ – francois P Nov 14 '18 at 17:47

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