How to find the right Programmable Logic Circuits AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Programmable Logic Circuits
- Device type
- Use an SPLD/GAL for a few gates of glue logic, a CPLD for instant-on glue logic and decoding, and an FPGA for large designs, soft CPUs or DSP. Each type differs in capacity, cost, startup behaviour and toolchain complexity, so match the type to the job.
- Configuration storage
- Check whether the device stores its configuration in internal flash or is SRAM-based and needs an external configuration flash. SRAM-based FPGAs lose their configuration at power-off, and forgetting the boot flash is a common design mistake.
- Toolchain and programmer
- Confirm that the vendor tool (Vivado, Quartus, Lattice Diamond/Radiant, Libero, Efinity, Gowin EDA) or the open-source flow (Yosys/nextpnr) supports the exact device, and that you have a compatible JTAG programmer. An unsupported part or a missing programmer leaves the chip unusable, and older parts often need legacy tool versions.
- I/O voltage
- Check the I/O bank voltages and 5 V tolerance against your system, because most modern FPGAs and CPLDs are not 5 V tolerant. Driving 5 V into a 3.3 V or lower bank can damage the device.
- Package
- Choose QFP or TQFP for hand assembly, and treat BGA parts as needing reflow and a multilayer board. Many capable FPGAs come only in BGA, which is impractical without assembly equipment.
- Capacity and hard blocks
- Size by LUTs or logic elements, block RAM, DSP multipliers, PLLs and transceivers, and leave headroom of about a third or more. Designs grow over time, and routing becomes difficult as utilisation climbs toward full.
Brands that matter
- AMD (Xilinx): Spartan, Artix and Zynq families, with Vivado tools.
- Altera: MAX CPLDs and Cyclone and Agilex FPGAs, with Quartus tools.
- Lattice Semiconductor: Small, low-power FPGAs. iCE40 and ECP5 are well supported by open-source tools.
- Microchip: PolarFire and IGLOO flash-based FPGAs, plus ATF16V8/22V10 SPLDs for simple glue logic.
- Efinix: Low-cost Trion and Titanium FPGAs.
- Gowin: Low-cost FPGAs common on hobby boards.
What to avoid
- Bare BGA FPGAs for learning or prototyping. Buy a development board instead.
- Old or discontinued GAL/PAL parts unless you have a programmer that supports them.
- Surplus or unbranded FPGAs from unknown sellers, because remarked and counterfeit parts are common.
- Assuming 5 V tolerance on any modern CPLD or FPGA I/O.
Questions
Should I use a CPLD or an FPGA?
A CPLD is instant-on, non-volatile and simple, which suits address decoding and glue logic. An FPGA has far more capacity for processors, video or signal processing, but it usually needs external configuration flash and more complex power rails.
Can I program an FPGA without vendor software?
For some families, yes. The open-source Yosys and nextpnr flow supports Lattice iCE40 and ECP5 and some Gowin parts. Most AMD and Altera devices still require the vendor tools.