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SN74ACT7803DL 数据表(PDF) 8 Page - Texas Instruments |
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SN74ACT7803DL 数据表(HTML) 8 Page - Texas Instruments |
8 / 16 page SN74ACT7803 512 × 18 CLOCKED FIRST-IN, FIRST-OUT MEMORY SCAS191C – MARCH 1991 – REVISED APRIL 1998 8 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 offset values for AF/AE The AF/AE flag has two programmable limits: the almost-empty offset value (X) and the almost-full offset value (Y). They can be programmed after the FIFO is reset and before the first word is written to memory. If the offsets are not programmed, the default values of X = Y = 64 are used. The AF/AE flag is high when the FIFO contains X or fewer words or (512 – Y) or more words. Program enable (PEN) should be held high throughout the reset cycle. PEN can be brought low only when IR is high and WRTCLK is low. On the following low-to-high transition of WRTCLK, the binary value on D0–D7 is stored as the almost-empty offset value (X) and the almost-full offset value (Y). Holding PEN low for another low-to-high transition of WRTCLK reprograms Y to the binary value on D0–D7 at the time of the second WRTCLK low-to-high transition. When the offsets are being programmed, writes to the FIFO memory are disabled, regardless of the state of the write enables (WRTEN1, WRTEN2). A maximum value of 255 can be programmed for either X or Y (see Figure 4). To use the default values of X = Y = 64, PEN must be held high. 34 RESET WRTCLK PEN WRTEN1 WRTEN2 D0–D7 IR X and Y Y Figure 4. Programming X and Y Separately absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage range, VCC –0.5 V to 7 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Input voltage range, VI –0.5 V to 7 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Voltage range applied to a disabled 3-state output 5.5 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Package thermal impedance, θJA (see Note 1) 74 °C/W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Storage temperature range, Tstg –65 °C to 150°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . † Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTE 1: The package thermal impedance is calculated in accordance with JESD 51. |
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类似说明 - SN74ACT7803DL |
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