74LS189 PDF – 64-bit Random Access Memory

This post explains for the TTL Memory.

The Part Number is 74LS189.

The function of this semiconductor is 64-bit Random Access Memory.

The Package: DIP 16 Pin type

Manufacturer: TI, Fairchild


74LS189 pdf ttl


The 74LS189 is a high speed 64-bit RAM orgainized as a 16-word by 4-bit array. Address inputs are buffered to minimize loading and are fully decoded on-chip. The outputs are 3-state and are in the high impedance state whenever the Chip select (CS) input is HIGH. The outputs are active only in the Read mode and the output data is the complement of the stored data.

The “74” in the name refers to the series of TTL (Transistor-Transistor Logic) integrated circuits manufactured by Texas Instruments. The “LS” indicates that it is part of the low-power Schottky family of TTL chips.

The 74LS189 is commonly known as a 16×4 RAM, meaning it can store 16 different 4-bit words (or 64 bits in total). Each word can be accessed independently through an address input. The chip has four data inputs (D0-D3) for writing data, four data outputs (Q0-Q3) for reading data, and two control inputs (CS and W) for chip select and write enable operations, respectively.


74LS189 datasheet pinout


1. 3-State Ouputs For Data BUS Applications

2. Buffered Inputs Minimize Loading

3. Address Decoding ON-Chip

4. Diode Clamped Inputs Minimize Ringing


74LS189 block diagram

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