What types of programmable logic equipment are there?
Today, manufacturers of programmable ASIC devices include Xilinx, Altera, Lattice, Actel, Atmel, AMD, Cypress, Intel, Motorola, TI, etc. Various manufacturers have different kinds of series and product titles, and the structure and classification of equipment are even more different. This section introduces several common classification methods.
1. Classification from the level of integration of programmable logic equipment
1. Low-density programmable logic equipment
Generally, when the number of equivalent gates in the PLD does not exceed 500 gates, it is considered to be a low-density PLD. According to this specification, PROM, PLA, PAL and GAL equipment are classified as low-density programmable logic equipment.
2. High-density programmable logic equipment
Generally, when the number of equivalent gates in a PLD crosses 500 gates, it is considered to be a high-density PLD. According to this specification, CPLD and FPGA are classified as high-density programmable logic equipment.
2. Categorize from mutual connection structure
1. Determine the type
Determined PLD means that the interconnection structure is completed with the same interconnect line every time, so the delay of the line can be guessed. Contains abbreviated PLD equipment (PROM, PLA, PAL and GAL) and CPLD. Today, with the exception of FPGA devices, this type of structure is basically the case.
2. Accounting type
refers to the fact that the planning system can perform different functions every time, and can provide different wiring methods. Usually, it is impossible to predict the delay of the line locally. The typical representative of the accounting structure is FPGA.
3. Classification from programming elements
Fuse switch is the earliest programmable element, which is composed of fuses. It is a one-time-programmable device. Its defects are large area, high current demand, and difficulty in inspection, such as XC5000 series devices such as PROM, PAL, and Xilinx.
The intention of the anti-fuse switch to reach the connecting line after the breakdown medium.
2. Floating gate programming skills
Use the floating gate to store charge to keep the programming data. So when the power is off, the stored data will not be thrown away. Both GAL and CPLD are programmed in this way.
Use static memory SRAM to store equipment data, called equipment memory. Now FPGAs produced by Xilinx have primarily chosen this programming structure. This SRAM is equipped with storage and has strong anti-jamming. The configuration data will be thrown away after each power-off, and it needs to be re-configured each time the power is turned on.
4. Classification by programmable features
1. One-time programmable
Fuse or antifuse equipment can only be written once, so it is called one-time programming, and other methods of programming equipment can be programmed repeatedly. Typical products that are once programmable are PROM, PAL, fuse, and anti-fuse FPGAs.
2. Repeatable programming
In the reprogrammable equipment, the number of times of programming of goods erased with ultraviolet rays is usually in the order of tens of times; the number of times of using the electrical erasing method is slightly more, and the number of erasing times of products with E2CMOS skills can reach thousands. Select the SRAM equipped structure, it is thought that the infinite programming can be completed.
If you want to know more, our website has product specifications for programmable logic equipment, you can go to ALLICDATA ELECTRONICS LIMITED to get more information