Member of the Texas Instruments

WidebusE Family

Free-Running Read and Write Clocks Can

Be Asynchronous or Coincident

Read and Write Operations Synchronized

to Independent System Clocks

Input-Ready Flag Synchronized to Write

Clock

Output-Ready Flag Synchronized to Read

Clock

512 Words by 18 Bits

Low-Power Advanced CMOS Technology

Half-Full Flag and Programmable

Almost-Full/Almost-Empty Flag

Bidirectional Configuration and Width

Expansion Without Additional Logic

Fast Access Times of 12 ns With a 50-pF

Load and All Data Outputs Switching

Simultaneously

Data Rates up to 67 MHz

Pin-to-Pin Compatible With SN74ACT7805

and SN74ACT7813

Packaged in Shrink Small-Outline 300-mil

Package Using 25-mil Center-to-Center

Spacing

description

The SN74ACT7803 is a 512-word × 18-bit FIFO

suited for buffering asynchronous datapaths up to

67-MHz clock rates and 12-ns access times. Two devices can be configured for bidirectional data buffering

without additional logic. Multiple distributed VCC and GND pins, along with Texas Instruments patented output

edge control (OECE) circuit, dampen simultaneous switching noise.

The write clock (WRTCLK) and read clock (RDCLK) are free running and can be asynchronous or coincident.

Data is written to memory on the rising edge of WRTCLK when WRTEN1 is high, WRTEN2 is low, and input

ready (IR) is high. Data is read from memory on the rising edge of RDCLK when RDEN, OE1, and OE2 are low

and output ready (OR) is high. The first word written to memory is clocked through to the output buffer,

regardless of the RDEN, OE1, and OE2 levels. The OR flag indicates that valid data is present on the output

buffer.

The FIFO can be reset asynchronously to WRTCLK and RDCLK. RESET must be asserted while at least four

WRTCLK and four RDCLK rising edges occur to clear the synchronizing registers. Resetting the FIFO initializes

the IR, OR, and half-full (HF) flags low and the almost-full/almost-empty (AF/AE) flag high. The FIFO must be

reset upon power up.

The SN74ACT7803 is characterized for operation from 0°C to 70°C.