MM74C89

· Wide supply voltage range: 3.0V to 15V
· Guaranteed noise margin: 1.0V
· High noise immunity: 0.45 V_CC (typ.)
· Low power TTL compatibility: fan out of 2 driving 74L
· Low power consumption: 100 nW/package (typ.)
· Fast access time: 130 ns (typ.) at V_CC = 10V
· 3-STATE output

The MM74C89 is a 16-word by 4-bit random access read/write memory. Inputs to the memory consist of four address lines, four data input lines, a write enable line and a memory enable line. The four binary address inputs are decoded internally to select each of the 16 possible word locations. An internal address register MM74C89 latches the address information on the positive to negative transition of the memory enable input. The four 3-STATE data output lines working in conjunction with the memory enable input provide for easy memory expansion.

Address Operation: Address inputs of MM74C89 must be stable tSA prior to the positive to negative transition of memory enable. It is thus not necessary to hold address information stable for more than tHA after the memory is enabled (positive to negative transition of memory enable).

Write Operation: Information present at the data inputs of MM74C89 is written into the memory at the selected address by bringing write enable and memory enable LOW.