5 ns speed grade — what it buys you in a 5V logic system
The GAL16V8D-5LJ: The 5 ns propagation delay (tpd) sets the maximum combinatorial logic path the part can handle at a given clock rate. At 5V nominal, this translates to a toggle rate around 100-125 MHz for registered logic, though the internal feedback path and output loading will reduce the usable frequency. For a 5V bus interface or address decoder, the 5 ns grade means the output settles within one 74LS TTL gate delay — no wait states needed on a 10 MHz bus. Eight macrocells give you eight registered or combinatorial outputs, each configurable as a sum-of-products term. This is enough for glue logic like a 3-to-8 decoder, a simple state machine with 4-6 states, or a bus arbiter for 2-3 masters. The 20-pin PLCC package limits I/O to 16 pins (8 dedicated inputs plus 8 I/O macrocells), so the logic density is constrained by pin count as much as by macrocell count.
Lattice has marked the GAL16V8D-5LJ as Obsolete. The part is no longer supported for new designs; existing BOM lines must be sourced through independent surplus or broker channels. For a legacy BOM that cannot be redesigned, the 5V supply rail and 5 ns speed grade narrow the field of drop-in replacements. The GAL16V8 family has been second-sourced historically (e.g., AMD, National), but those versions are also long obsolete. Any replacement candidate must match the 20-PLCC footprint, 5V-only I/O, and the JEDEC fuse-map format — a pin-compatible 3.3V or 1.8V CPLD will not drive a 5V TTL bus without level translation.
Package, temperature, and supply — board-fit checklist
20-PLCC (J-Lead) package, 9x9 mm body. The J-lead footprint requires a PLCC socket or a reflow profile with a peak temperature around 220-235°C for SnPb solder. Commercial temperature range: 0°C to 75°C ambient. This part is not rated for industrial (-40°C) or automotive environments. Supply voltage is 4.75V to 5.25V — a tight 5V ±5% rail.