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CD74HC40105M 数据表(PDF) 2 Page - Texas Instruments |
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CD74HC40105M 数据表(HTML) 2 Page - Texas Instruments |
2 / 21 page 2 Pinout CD54HC40105, CD54HCT40105 (CERDIP) CD74HC40105, CD74HCT40105 (PDIP, SOIC) TOP VIEW Loading Data Data can be entered whenever the DATA-IN READY (DIR) flag is high, by a low to high transition on the SHIFT-IN (SI) input. This input must go low momentarily before the next word is accepted by the FIFO. The DIR flag will go low momentarily, until the data have been transferred to the sec- ond location. The flag will remain low when all 16-word loca- tions are filled with valid data, and further pulses on the SI input will be ignored until DIR goes high. Unloading Data As soon as the first word has rippled to the output, the data- out ready output (DOR) goes HIGH and data of the first word is available on the outputs. Data of other words can be removed by a negative-going transition on the shift-out input (SO). This negative-going transition causes the DOR signal to go LOW while the next word moves to the output. As long as valid data is available in the FIFO, the DOR signal will go high again, signifying that the next word is ready at the output. When the FIFO is empty, DOR will remain LOW, and any further commands will be ignored until a “1” marker ripples down to the last control register and DOR goes HIGH. If during unloading SI is HIGH, (FIFO is full) data on the data input of the FIFO is entered in the first location. Master Reset A high on the MASTER RESET (MR) sets all the control logic marker bits to “0”. DOR goes low and DIR goes high. The contents of the data register are not changed, only declared invalid, and will be superseded when the first word is loaded. Thus, MR does not clear data within the register but only the control logic. If the shift-in flag (SI) is HIGH during the master reset pulse, data present at the input (D0 to D3) are immediately moved into the first location upon completion of the reset process. Three-State Outputs In order to facilitate data busing, three-state outputs (Q0 to Q3) are provided on the data output lines, while the load condition of the register can be detected by the state of the DOR output. A HIGH on the three-state control flag (output enable input OE) forces the outputs into the high-impedance OFF-state mode. Note that the shift-out signal, unlike that in the CD40105B, is independent of the three-state output control. In the CD40105B, the three-state control must not be shifted from High to Low when the shift-out signal is Low (data loss would occur). In the high-speed CMOS version this restriction has been eliminated. Cascading The 40105 can be cascaded to form longer registers simply by connecting the DIR to SO and DOR to SI. In the cascaded mode, a MASTER RESET pulse must be applied after the supply voltage is turned on. For words wider than four bits, the DIR and the DOR outputs must be gated together with AND gates. Their outputs drive the SI and SO inputs in parallel, if expanding is done in both directions (see Figures 12 and 13). Functional Diagram 14 15 16 9 13 12 11 10 1 2 3 4 5 7 6 8 THREE-STATE DIR SI D0 D1 D2 GND D3 VCC DOR Q0 Q1 Q2 Q3 MR SO CONTROL STATE Q0 Q1 Q2 Q3 CONTROL D0 D1 D2 D3 SHIFT OUT 4 1 5 6 7 3 15 13 12 11 10 MASTER 9 SHIFT IN RESET 14 2 DATA-OUT DATA-IN READY READY GND = 8 VCC = 16 THREE- CD54HC40105, CD74HC40105, CD54HCT40105, CD74HCT40105 |
类似零件编号 - CD74HC40105M |
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类似说明 - CD74HC40105M |
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