7400 series integrated circuits ICs

7400 Series integrated circuits (ICs) have a lot of ready to use logic gates and various other circuits within them.

74xx…

  • The number is 74 to indicate the series of integrated circuits
  • Then there are usually 2 letters (but not always) after the 74 to indicate the type of transistors that are built into IC. HC (High Speed CMOS) is most common now, but LS (Low Power Schottky) used to be the most common. You will often see “xx” in place of those letters to indicate that odds are, there will be 2 letters of a yet unknown version.

High Speed CMOS (74HCxx) is the standard variation of the 7400 series ICs to learn about and use these days. They usually can replace a 74LSxx ICs of the same circuits, whereas the 74LSxx ICs usually can not be used to replace a 74HCxx IC.  

  • After those 2 letters, there is another 2 or 3 digit number that is used to indicate the circuits on the chip. 74xx00 is a quad 2 input NAND gate. 74xx14 is a Hex inverters with Schmitt trigger inputs IC.
  • 54xxxx instead of 74xxxx indicates that it is built to military specifications. You will often see 5400 series ICs on the same datasheet as the 7400 series component.

Letter(s) added before the part number usually indicates the manufacturer and has nothing to do with the operation of the IC. Not a guarantee though.

  • SN74xxxx – Texas Instruments (TI).
  • M74xxxx – STMicroelectronics.
  • MC74xxxx – On semiconductor.
  • DM74xxxx – Fairchild Semiconductors.

Examples:

Numbers obtained from Texas Instrument datasheets. TI starts off their 7400 series IC with SN. Other manufactures probably start of the the same component with different letters, but the component itself is probably made to the same specifications.

Warning! Datasheets often include multiple versions of a component. Make sure each specification you are looking at is for your specific component. I may accidently post the specs for the wrong version from time to time. Always consult the actual datasheet itself.

Quad 2 input (positive) NAND gate:

  1. SN7400 – original version of the integrated circuit.
    • Absolute max. supply voltage = 7V
    • Absolute max. input voltage = 5.5V
    • Recommended supply voltage = Min. 4.75V – Max. 5.25V
    • High level input voltage = 2V Min
    • TTL logic outputs
    • High level output current = Not given on datasheet
    • Low level output current = Max 16mA
  2. SN74LS00  Quad 2 Input Positive NAND Gate – Low power Schottky version of the integrated circuit.
    • Absolute max. supply voltage = 7V
    • Absolute max. input voltage = 7V
    • Recommended supply voltage = Min. 4.75V – Max. 5.25V
    • High level input voltage = Min 2V
    • TTL logic outputs
    • High level output current = Max -0.4mA
    • Low level output current = Max 4mA
  3. SN74HC00 – High speed CMOS version of the integrated circuit.
    • Absolute max. supply voltage = 7V
    • Recommended supply voltage = Min. 2V – NOM. 5V – Max. 6V
    • Continuous output current = ±25mA
    • Continuous current through Vcc or GND = ±50mA
    • High level input (depends on Vcc voltage)
      • Vcc = 2V – Min. 1.5V
      • Vcc = 4.5V – Min. 3.15V
      • Vcc = 6V – Min. 4.2V
    • Low level input (depends on Vcc voltage)
      • Vcc = 2V – Max. 0.5V
      • Vcc = 4.5V – Max. 1.35V
      • Vcc = 6V – Max. 1.8

Fan out: how many 74LSxx inputs can be driven by an output.

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