Logic Chips

1
Logic Chips
Actual circuit is on a small chip of silicon
Standard chips use either TTL (Transistor-Transito
r Logic), or CMOS transistors
Pins are connected to chip with internal wires
Package Made of plastic or ceramic
Pin number one is identified with a dot or notch
Pins are numbered in a counter-clockwise fashion
2
Logic Chips 7400 NAND
Part number 74xx00 is a 7400 Quad Nand Gate
Vcc
LS Low-Power Schottky TTL HC CMOS HCT
TTL-compatible CMOS F Fast TTL
74LS00
There are four 2-input NAND gates in a 7400
GND
All chips have connections to Vcc (5) and GND
Usually pins 14 and 7
3
Logic Chips Inverters and NORs
74xx04 Hex Inverter
74xx02 Quad NOR Gate
4
Logic Families
5V TTL
5V CMOS
Standard Low-Power Schottky LS Fast - F
Standard - HC HCT TTL compatible
High
High
High
High
Low
Low
Low
Low
WARNING Dont mix TTL and HC
5
Finding Info on Chips

• Search online
• Enter the part number, with family code
• 74LS02 datasheet
• 74HC00 datasheet
• Basic functionality is easy to find
• Timing info may require looking up the exact
  manufacturer

6
Making a logic circuit
Convert to NANDs
A
B
C
T2
T1
F
7
Prototyping Breadboards
Connections for Power/GND
Connections from chip to chip
-
-


f g h i j
a b c d e
-
-


/- Are connected in columns. Used for
connections to 5V and GND.Note On some boards,
they are split in the middle
a/b/c/d/e and f/g/h/i/j are connected in rows.
Used for connecting to chips. Note They are not
connected in the middle.