PC/CP120 Digital Electronics Lab

Introducing Integrated Circuits

Objective:

• Indentify an IC
• Read the datasheet for an IC
• Wire a circuit including a debugger board
• Test an IC

Background:

In PC/CP120 labs we'll walk you through wiring a simple gate circuit using one specific integrated circuit (IC) the 7400 chip. It's a good introduction to some of the more complex logic chips that you'll be using later in the lab.

The 7400 device is part of the 74xx family of integrated circuits. (The xx refers to the fact that there are many possible numbers which follow the 74.) For more info about the 74xx family see Wikipedia.

IC pin numbering and orientation

Locate the 7400 chip/IC in your lab kit. This chip has SN74LS00N written on it. Note that there are 5 parts to the chip "number":

1. A text prefix; eg. SN
   • This indicates the manufacturer
2. The numbers 74
   • This indicates the logic family;
   • in this case, normal TTL
   • (54 would indicate military-spec TTL)
3. More text; eg. LS
   • This indicates the sub-family
   • (You may even see chips with no letters here, meaning the original "plain" TTL.)
4. More numbers; e.g. 00
   • This indicates the specific device;
   • in this case, a quad 2 input NAND gate
5. A text suffix; eg. N
   • This indicates the package type
   • (This will indicate which version of the pinout applies to this chip.)

Normally you will just refer to the device by using the two sets of numbers, such as 7400, and ignore the letters.

The LS tells you that it is a low power Schottky chip. The manufacturer includes other information along with the 74LS00 on the chip.
This is a Dual-Inline Package (DIP), referring to the chip's two rows of pins. Notice that this chip has fourteen pins. If you want to use an IC chip, then you will always need to know the pinout. That's electrical engineering lingo for describing the way the pins are connected to the internal circuitry of the chip. You need to know where the power supply is connected and where the gate inputs and outputs are connected.

How do you know the IC pinout? You will need to look at the IC's datasheet. The manufacturer provides you with the IC datasheets for all of their products. See 7400 datasheet for an example.
For the 74-series IC data sheet index see this link

Here's a picture of the 7400 chip in a circuit board:

and here's the pinout for a 7400 chip:

How do you know which pin is "pin 1" on the IC? You will find either a circle marking the first pin or a semicircle marking the top of chip. The pins on an N-pin DIP are numbered as shown :

.

Task:

Parts List

• breadboard
• debugger board
• NAND gate (7400)
• Wires

1. Wire up the debugger board with one gate on the 7400 chip. Be sure to apply power and ground to both the chip and the debugger board.
2. Use the four possible input combinations to the gate to show that it performs as expected.