The 74HC/HCT40105 4-bit x 16-word FIFO register is a high-speed Si-gate CMOS device and is pin compatible with the 40105 of the 4000B series. It can store sixteen 4-bit words and is capable of handling input and output data at different shifting rates. This feature makes it particularly useful as a buffer between asynchronous systems.
The Philips 74HC/HCT40105 is a high-speed Si-gate CMOS device functioning as a 4-bit x 16-word first-in/first-out (FIFO) storage register. It is pin compatible with the 4000B series and is specified in compliance with JEDEC standard no. 7A. The device features independent asynchronous inputs and outputs, a reset capability, and status indicators on both inputs and outputs.
| Capacity | 4-bit x 16-word |
|---|---|
| Propagation delay (MR to DIR, DOR) | 16 ns (HC), 15 ns (HCT) |
| Maximum clock frequency | 33 MHz (HC), 31 MHz (HCT) |
| Package types | DIP16, SOT109-1, SSOP16, TSSOP16 |
DIR = HIGH indicates the input stage is empty and ready to accept valid data, while DIR = LOW indicates the FIFO is full or busy.
The size can be reduced from 4 x 16 to 1 x 16 by tying unused data input pins to Voc or GND.
When MR is HIGH, the control functions are cleared, data content is declared invalid, DIR is set HIGH, and DOR is set LOW.