7490compatible

7490compatible refers to hardware, modules, or designs that are intended to work with the 7490 family of four‑bit counters used in digital logic circuits. The term is commonly found in product documentation and design notes to indicate that a part can be used in place of a CD7490 or other 7490‑style counters, or that it will interoperate in circuits built around such counters. The goal of compatibility is to preserve the basic functional behavior and the essential electrical interfaces.

Key compatibility aspects typically claimed include a matching or compatible pinout for the clock, reset, and count outputs; similar timing characteristics with respect to clock edges and reset behavior; and the ability to cascade multiple devices to extend counting range. In practice, vendors may also aim for similar logic levels and drive requirements to fit within common TTL or CMOS operating environments.

When selecting a 7490‑compatible part, engineers consult datasheets to confirm pin assignments, reset/preset behavior, propagation delays, and output drive. It is important to verify power supply ranges and clock frequency limits, as these can differ between TTL and CMOS variants. Substitution decisions should also consider any subtle differences in reset or preset semantics that could affect cascading or integration with other logic.

Limitations: “7490-compatible” is not an official standard; it signifies compatibility in a given context but does not guarantee complete interchangeability under all conditions. Users should validate in their specific circuit and operating environment.

See also: 74x90 family, CD7490, TTL counters, CMOS counters.