SENG 2004-08-26

Info (C)PLD

Informations and answers

(C)PLD - what's this?
(C)PLD´s ((Complex) Programmable Logic Device´s are integrated, programmable and non volatile (Flash or EeProm based) logic circuits. PLD's are the probably oldest kind of programmable logic. The component immediately enters it´s working condition after power up, without any external configuration circuitry. Therefore it is capable to control a system´s boot process or participate in it. It contains macro cells consisting of a And/Or matrix with attached memory cell. One component can contain between 8 and some hundred macro cells. Logic behavioural and internal signal feedbacks are programmable. Programming can be done via various hardware description languages or schematic entry. Due to it´s simple internal structure, pin to pin delays are small and easily calculable. The gate count / complexity is limited.

For what can (C)PLD´s be used for ?
To integrate any kind of digital, not complex, however fast logic. Classical applications: address decoding, state-machines, wait-state logic.

Which advantages/disadvantages do (C)PLD´s offer ?
Components are immediately active after power up, pin to pin delay can be very small.
Hierarchical and complex structures can not be implemented into these elements.