The 74HC; 74HCT is an 8-bit buffer/line driver with 3-state outputs. The device can be used as two 4-bit buffers or one 8-bit buffer. Buffers: vs is an octal unidirectional buffer. The 8 lines can be split into two groups and each group can be individually. Electrical Engineering Glossary of Electronic Terms, 8-Bit Buffer IC, functional schematic diagram, true table and package out-line. 74HCT
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Note that the chip displayed indicates OE control of the output [Output Enable].
Buffers: vs – Geek went Freak!
So the outputs could be taken tri-state if required. The functional IC is split into two 4-bit sections, so they could be operated together or separately, driving one 8-bit bus or two separate 4-bit buses. Design Hint; Because this chip is used to drive a bus, which may be capacitive loaded, use more than the normal by-pass capacitor to insure that the IC has the current it needs when the buffers begin to drive the bus. Using just the standard.
Also refer to Logic Family vs Switching Speed.
Add a second by-pass capacitor, and place both by-pass capacitors as close to the Vcc line as possible. These buffers are normally available in a number of package styles; however only the surface mount PSOP is shown. Other than size, Lead Inductance is the next important issue because it slows down switching time, while the size of the IC package causes the placement of the capacitor to move away from the power leads of the IC.
Buffers: 74244 vs 74245
The type or family of buffer used does make a difference in the table above, just the trailing digits that indicate the type of buffer [as in the different options]. Regardless of biffer family used, just be sure to provide by-pass next to the IC. Also, if possible run a larger trace to the IC or capacitor to insure the chip has the highest possible chance of getting the current it needs as fast as possible.
The location of the bypass capacitor is extremely important; read more on Capacitor Placementas it applies to IC by-passing. Note the part number suffix is omitted.
The suffix is used to define the package style [which is listed] and the packaging bufer during shipping [which is a don’t care]. Finally, note that the manufacturer is not listed here either. The buffsr of this list is to indicate that a government agency could attempt to procure these items based on the VID number provided.
Note that 54xx devices are listed to the left and only the 74xx devices are listed above. Pick a series [54x] if need the temperature range, otherwise use the series [74x]. However what is available in the IC family may also come into play.
That’s what can be delivered faster, or has a lower lead time, or faster deck date. Although one may cost more that the other, but a small price to pay for time to market.