Download - PROGRAMMABLE LOGIC DEVICES PATR 2 OF 2
Programmable Array Logic (PAL) is a family of programmable logic device semiconductors used to implement logic functions in digital circuits introduced by Monolithic Memories
PROGRAMMABLE ARRAY LOGIC
Programmable
ANDarray
FixedOR
array
N input
product term
Out puts
The connection in AND array is programmable and in OR array is not .
It has n i/p line which is given to the buffer Buffer are connected to the i/p of the AND
gate programmable link Output of the gate is then fed to the OR
array With fixed connection. All the output of the AND array is not
connected to the OR array
In PAL only AND array is programmable but in PLA both AND and OR array are programmable
Main difference b/t PAL and PLA
A complex programmable logic device (CPLD) is a programmable logic device with complexity between that of PALs and FPGAs, and architectural features of both.
COMPLEX PROGRAMMABLE
LOGIC DEVICES
STRUCTURE OF CPLDI/PBLOCK
PALLIKE
BLOCK
PALLIKE
BLOCK
I/PBLOCK
INTERCONNECT WIRE
I/PBLOCK
PALLIKE
BLOCK
PALLIKE
BLOCK
I/PBLOCK
CPLDs are the extension of the PAL concept
It consist of number of pal like logic block has a programmable AND array that feed macro cell and the output of these macro cell can be rooted to the input of the other logic block within the same ic’s
CPLDs are electrically erasable and reprogrammable .
CPLD is non-volatile and can be programmed by –
- design entry and simulation - transforming the programing information generated by CAD system through cable from computer to CPLD
Features
A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturing—hence "field-programmable".
FIELD PROGRAMMABLE GATE ARRAY
Most commonly used logic block is a look up table, which contain storage cell that are used to implement a small logic function.
Each cell is capable of holding a single value either zero or one
Consumer product like dvd player
Controller circuit for automobile
Internet router, network switches
Application
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