24,000 gates in a 84-PLCC — the glue-logic workhorse
The Microchip A42MX16-PLG84 is an MX-series FPGA packing 24,000 gates in a 84-pin PLCC package. That gate count puts it in the range for moderate-density bus bridging, address decoding, state-machine control, and custom peripheral muxing — not for processor-class logic, but enough to replace a handful of 7400-series or 4000-series logic ICs on a board. Seventy-two user I/O are available, which is enough to fan out to a 16-bit data bus plus address and control lines with headroom for a few status and configuration signals. The 3 V supply rail means it runs directly from a 3.3 V rail without a separate regulator — one less BOM line.
That locks this part into indoor, temperature-controlled equipment — office peripherals, test gear, telecom racks with active cooling, consumer electronics. Not for an engine bay, a rooftop radio, or an unventilated enclosure in a warehouse. Surface-mount assembly in an 84-PLCC — the J-lead footprint is a known quantity for rework and inspection. The PLCC socket option exists for prototyping or field-upgradeable designs, but production boards typically solder direct.
The MX series has been a long-running antifuse FPGA family. Active status on a mature part like this is a signal of stable supply — no die-shrink respin, no package-change PCN looming. The risk profile is low for a production line that needs a known, fixed logic footprint.
Gate-count delta vs the A40MX04-PLG84
The closest sibling in the MX family is the A40MX04-PLG84, which holds 6,000 gates and 69 I/O in the same 84-PLCC package. The A42MX16-PLG84 offers 4× the gate count and three additional I/O — a meaningful step up if your design needs more combinatorial logic or wider bus fan-out, but still pin-compatible on the same board footprint. If the 6,000-gate variant is enough for the logic load, the A40MX04-PLG84 saves cost. If you need the extra headroom, the A42MX16-PLG84 is the drop-in upgrade without a board spin.