New 3.3-V FIFOs maintain 5-V performance

A new, low-power 3.3-V family of First-In First-Out (FIFO) memories from Texas Instruments allows high-performance workstations and desktop multimedia systems to consume less power while maintaining the performance of 5-V FIFOs.

"In contrast to other vendors who may have scaled back or re-characterized 5-V CMOS FIFOs to run at 3.3-V, we have designed these new FIFOs to optimally run with a 3.3-V power supply," said Neil Hejny, TI's FIFO strategic marketing manager.

"Simply scaling back a FIFO is easier than developing a new design, but re-characterized FIFOs often achieve 40 percent less performance in operating frequencies, propagation delays and drive capability than 5-V devices."

Designated the SN74ALVC78xx family, the devices are designed to interface to high-speed microprocessors and digital signal processors (DSPs), such as TI's high-performance 3.3-V floating point DSPs and its TMS320C80 Multimedia Video Processor. The new devices are 18-bit Widebus FIFOs based on advanced low voltage CMOS (ALVC) technology. They are pin-for-pin compatible with TI's 5-V FIFO product family.

The FIFOs are organized in depths of 64, 256 or 512 bits and offer speed sorts of 20, 25 or 40 nanoseconds (ns). FIFOs in the 'ALVC78xx family use either TI's innovative clocked architecture or a strobed design.

The devices are available now in a 56-pin SSOP from TI and its authorized distributors.

3.3-V FIFOs at a glance

                             Speed         SRP

Device          Architec.     sort (ns)	(1K qty.)

------------------------------------------------

SN74ALVC7803    Clocked        20         $26.36

                Clocked        25         $21.99

                Clocked        40         $14.74

------------------------------------------------

SN74ALVC7804    Strobed        25         $13.66

                Strobed        40         $11.81

------------------------------------------------

SN74ALVC7805    Clocked        20         $31.71

                Clocked        25         $27.98

                Clocked        40         $19.64

------------------------------------------------

SN75ALVC7806    Strobed        25         $18.24

                Strobed        40         $15.35

------------------------------------------------

SN74ALVC7813    Strobed        20         $27.50

                Strobed        25         $24.15

                Strobed        40         $17.43

SN74ALVC78XX 3.3-V FIFO memories

Clocked architecture features

• Free running read and write clocks can be asynchronous or coincident
• Input-ready and output-ready flags can be synchronized to the system's write and read clocks respectively
• Fast access times starting at 13 ns with a 50 Pico-farad output load
• Data rates up to 50 MHz

Strobed architecture features

• Load or unload clock can be asynchronous or coincident
• Fast access times beginning at 18 ns with a 50 Pico-farad output load
• Data rates up to 40 MHz

May 1995, vol. 12, no. 4

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