DATASHEET
CD40105BMS FN3353
Rev 0.00
December 1992 CMOS FIFO Register Features Description 4 Bits x 16 Words CD40105BMS is a low-power first-in-first-out (FIFO) “elastic”
storage register that can store 16 4-bit words. It is capable of
handling input and output data at different shifting rates. This
feature makes it particularly useful as a buffer between asynchronous systems. High Voltage Type (20V Rating) Independent Asynchronous Inputs and Outputs 3-State Outputs Expandable in Either Direction Status Indicators on Input and Output Reset Capability Standardized Symmetrical Output Characteristics 100% Tested for Quiescent Current at 20V 5V, 10V and 15V Parametric Ratings Maximum Input Current of 1пЃA at 18V Over Full Package Temperature Range; 100nA at 18V and +25oC Noise Margin (Over Full Package/Temperature Range)
-1V at VDD = 5V
-2V at VDD = 10V
-2.5V at VDD = 15V Meets All Requirements of JEDEC Tentative Standard
No. 13B, “Standard Specifications for Description of
�B’ Series CMOS Devices” Each word position in the register is clocked by a control flipflop, which stores a marker bit. A “1” signifies that the position’s data is filled and a “0” denotes a vacancy in that position. The control flip-flop detects the state of the preceding
flip-flop and communicates its own status to the succeeding
flip-flop. When a control flip-flop is in the “0” state and sees a
“1” in the preceding flip-flop, it generates a clock pulse that
transfers data from the preceding four data latches into its
own four data latches and resets the preceding flip-flop to
“0”. The first and last control flip-flops have buffered outputs.
Since all empty locations “bubble” automatically to the input
end, and all valid data ripple through to the output end, the
status of the first control flip-flop (DATA-IN READY) indicates
if the FIFO is full, and the status of the last flip-flop (DATAOUT READY) indicates if the FIFO contains data. As the
earliest data are removed from the bottom of the data stack …
