IDT72V235

The IDT72V205/72V215/72V225/72V235/72V245 are functionally compatible versions of the IDT72205LB/72215LB/72225LB/72235LB/72245LB, designed to run off a 3.3V supply for exceptionally low power consumption. These devices are very high-speed, low-power First-In, First-Out (FIFO) memories with clocked read and write controls. These FIFOs are applicable for a wide variety of data buffering needs, such as optical disk controllers, Local Area Networks (LANs), and interprocessor communication.

These FIFOs have 18-bit input and output ports. The input port is controlled by a free-running clock (WCLK), and an input enable pin (WEN). Data is read into the synchronous FIFO on every clock when WEN is asserted. The output port is controlled by another clock pin (RCLK) and another enable pin (REN). The Read Clock(RCLK) can be tied to the Write Clock for single clock operation or the two clocks can run asynchronous of one another for dual-clock operation. An Output Enable pin (OE) is provided on the read port for three-state contro of the output.

The synchronous FIFOs have two fixed flags, Empty Flag/Output Ready (EF/OR) and Full Flag/Input Ready (FF/IR), and two programmable flags, Almost-Empty (PAE) and Almost-Full (PAF). The offset loading of the program  mable flags is controlled by a simple state machine, and is initiated by asserting the Load pin (LD). A Half-Full flag (HF) is available when the FIFO is usedin a single device configuration.

There are two possible timing modes of operation with these devices: IDT Standard mode and First Word Fall-Through (FWFT) mode.

In IDT Standard Mode, the first word written to an empty FIFO will not appear on the data output lines unless a specific read operation is performed. A read peration, which consists of activating REN and enabling a rising RCLK edge, will shift the word from internal memory to the data output lines. mable flags is controlled by a simple state machine, and is initiated by asserting the Load pin (LD). A Half-Full flag (HF) is available when the FIFO is used in a single device configuration.

There are two possible timing modes of operation with these devices: IDT Standard mode and First Word Fall-Through (FWFT) mode.

In IDT Standard Mode, the first word written to an empty FIFO will not appear on the data output lines unless a specific read operation is performed. A read operation, which consists of activating REN and enabling a rising RCLK edge, will shift the word from internal memory to the data output lines.

In FWFT mode, the first word written to an empty FIFO is clocked directly to the data output lines after three transitions of the RCLK signal. A REN does not have to be asserted for accessing the first word.

These devices are depth expandable using a Daisy-Chain technique or First Word Fall Through mode (FWFT). The XI and XO pins are used to expand the FIFOs. In depth expansion configuration, First Load (FL) is grounded on the first device and set to HIGH for all other devices in the Daisy Chain.

The IDT72V205/72V215/72V225/72V235/72V245 are fabricated using IDT's high-speed submicron CMOS technology.