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CMOS Digital
Integrated Circuits
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Most of the circuits you will build for
GCSE projects will be battery powered. For this reason we recommend you
use the CMOS 4000 series of integrated circuits
These chips have an operating voltage of between 2V
and 15V and because they use CMOS technology they use less power.
When designing and building circuits it is important
that the correct power connections are made. For CMOS chips VDD
indicates the +V connection and VSS the 0V connection.
Finding Pin 1 |
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On the top surface of a DIL
(dual in line) package is a notch or dot. Pin 1 is always to the left of
this dot or notch.
The IC shown is an 8 pin DIL IC. Most digital IC's are
14 pin DIL's but IC's with 16 or more pins are common.
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Digital Logic IC's
All 2-Input CMOS Logic Gate IC's have identical
pin-outs.
They are called quad 2-input
gate IC's because each chip contains 4 x 2-input logic gates
and the +v (VDD) and 0V (VSS) connections.
For this reason they each have 14 pins.
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Logic Gates
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| 4001
quad 2-input Nor gate |
4011
quad 2-input Nand gate |
4071
quad 2-input OR gate |
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| 4081
quad 2-input AND gate |
4070
quad 2-input X-OR gate |
4077
quad 2-input X-NOR gate |
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When combining
logic gates it is good practice to connect any
unused inputs to the OV supply rail.
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Inverters and Buffers
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| 4049
Hex inverting buffer |
4069
hex inverter |
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CMOS Counters/Decoders
and Drivers
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A
bar across the top of an input or output means that the pin has to be held
low to be active
i.e.  |
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| 4510
divide by 10 up/down counter |
4518
dual divide by 10 counter |
4520
dual divide by 16 counter |
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| 4511
7-segment latch/driver |
4017
divide by ten counter |
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