The AMD AM25LS2569/BRA is a 4-bit synchronous binary counter in a 20-pin DIP package, designed for up/down counting with positive-edge triggering and an asynchronous reset. It operates from a 4.75 V to 5.25 V supply and is rated across the full military temperature range of -55°C to 125°C, making it suitable for avionics, missile guidance, and other high-reliability systems where a hardened logic part is specified.
18 MHz count rate — what it means for the bus
The 18 MHz count rate sets the maximum input frequency the counter can reliably track. In a timing or frequency-division application, this means the input clock period must stay above roughly 55 ns to avoid missing edges. For a 5V TTL system, that is a comfortable margin for most backplane or peripheral buses, but it does limit use in high-speed serial or gigabit-class designs.
Supply and temperature grade
The 4.75 V to 5.25 V supply range is standard 5V TTL logic. The -55°C to 125°C operating range is the military-grade temperature span.
Package and mounting
Supplied in a 20-pin PDIP (20-DIP) with through-hole mounting. Bulk packaging means the parts ship in tubes or loose.