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I use a board where the designers uses a SN75451 chip. It is a dual AND gate chip with open collector output.

I am quite surprised as normally the 74xx09 would be used in order to implement AND gate with open collector output. Why in the world would we want to use a different chip?

It seems like LEDs can be lit directly from the chip so is it simply because it can drive a lot of current ? If so, why use this chips instead of a discrete transistor ?

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  • \$\begingroup\$ Banner line title: "Dual-Peripheral Drivers for High-Current, High-Speed Switching" \$\endgroup\$
    – sstobbe
    Commented Sep 26, 2017 at 16:10
  • \$\begingroup\$ Voting to close because this question is asking about the use of electronic devices, which is off-topic for this site. \$\endgroup\$
    – DerStrom8
    Commented Sep 26, 2017 at 16:48
  • \$\begingroup\$ Please do not change the question on the fly. It makes existing answers invalid and helps no-one. If you need to correct or add more, add it to the end of the question as an edit. \$\endgroup\$
    – Trevor_G
    Commented Sep 26, 2017 at 17:03
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    \$\begingroup\$ @sstobbe Banner lines such as "high-current" or "high-speed" does not mean anything if they don't say against which currents or speed they are comparatively "high". \$\endgroup\$
    – Bregalad
    Commented Sep 27, 2017 at 6:59

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Seriously...

The 451 is a dual open collector AND driver IC not a quad AND gate.

enter image description here

It can handle 400mA continuous. As you suspect, it is good for driving heavier loads at higher voltages like LEDs, small motors etc.

EDIT: Since you chose fit to change your question....

why use this chips instead of a discrete transistor

You could use discrete transistors, but that would be more real-estate to add two transistors than one device. Having said that, my guess is sales on this particular device were below engineering's expectations.

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    \$\begingroup\$ The 74xx09 is not a NAND gate, it is a quad AND gate \$\endgroup\$
    – DerStrom8
    Commented Sep 26, 2017 at 16:50
  • \$\begingroup\$ @DerStrom8 lol picky picky... corrected. \$\endgroup\$
    – Trevor_G
    Commented Sep 26, 2017 at 16:56
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    \$\begingroup\$ @DerStrom8 It was a 74xx00 NAND gate.. why the OP changed the original question I don't know... \$\endgroup\$
    – Trevor_G
    Commented Sep 26, 2017 at 16:58

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