поискавой системы для электроныых деталей |
|
SN74ACT2235-20FN датащи(PDF) 5 Page - Texas Instruments |
|
SN74ACT2235-20FN датащи(HTML) 5 Page - Texas Instruments |
5 / 18 page SN74ACT2235 1024 × 9 × 2 ASYNCHRONOUS BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY SCAS148F – DECEMBER 1990 – REVISED JUNE 2003 5 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 Terminal Functions TERMINAL† I/O DESCRIPTION NAME NO. I/O DESCRIPTION AF/AEA AF/AEB 15 30 O Almost full/almost empty flags. The almost-full/almost-empty A flag (AF/AEA) is defined by the almost-full/almost-empty offset value for FIFO A (X). AF/AEA is high when FIFO A contains X or fewer words or 1024 – X words. AF/AEA is low when FIFO A contains between (X + 1) or (1023 – X) words. The operation of the almost-full/almost-empty B flag (AF/AEB) is the same as AF/AEA for FIFO B. A0–A8 4–8, 10–13 I/O A-data inputs and outputs B0–B8 32–35, 37–41 I/O B-data inputs and outputs DAF DBF 21 24 I Define-flag inputs. The high-to-low transition of DAF stores the binary value on A0–A8 as the almost-full/almost-empty offset value for FIFO A (X). The high-to-low transition of DBF stores the binary value of B0–B8 as the almost-full/almost-empty offset value for FIFO B (Y). EMPTYA EMPTYB 25 20 O Empty flags. EMPTYA and EMPTYB are low when their corresponding memories are empty and high when they are not empty. FULLA FULLB 18 27 O Full flags. FULLA and FULLB are low when their corresponding memories are full and high when they are not full. HFA HFB 16 29 O Half-full flags. HFA and HFB are high when their corresponding memories contain 512 or more words and low when they contain 511 or fewer words. LDCKA LDCKB 17 28 I Load clocks. Data on A0–A8 is written into FIFO A on a low-to-high transition of LDCKA. Data on B0–B8 is written into FIFO B on a low-to-high transition of LDCKB. When the FIFOs are full, LDCKA and LDCKB have no effect on the data residing in memory. GAB GBA 43 2 I Output enables. GAB, GBA control the transceiver functions. When GBA is low, A0–A8 are in the high-impedance state. When GAB is low, B0–B8 are in the high-impedance state. RSTA RSTB 22 23 I Reset. A reset is accomplished in each direction by taking RSTA and RSTB low. This sets EMPTYA, EMPTYB, FULLA, FULLB, and AF/AEB high. Both FIFOs must be reset upon power up. SAB SBA 44 1 I Select-control inputs. SAB and SBA select whether real-time or stored data is transferred. A low level selects real-time data and a high level selects stored data. Eight fundamental bus-management functions can be performed as shown in Figure 2. UNCKA UNCKB 26 19 I Unload clocks. Data in FIFO A is read to B0–B8 on a low-to-high transition of UNCKA. Data in FIFO B is read to A0–A8 on a low-to-high transition of UNCKB. When the FIFOs are empty, UNCKA and UNCKB have no effect on data residing in memory. † Terminals listed are for the FN package. programming procedure for AF/AEA The almost-full/almost-empty flags (AF/AEA, AF/AEB) are programmed during each reset cycle. The almost-full/almost-empty offset value for FIFO A (X) and for FIFO B (Y) is either a user-defined value or the default values of X = 256 and Y = 256. Below are instructions to program AF/AEA using both methods. AF/AEB is programmed in the same manner for FIFO B. user-defined X Take DAF from high to low. This stores A0–A8 as X. If RSTA is not already low, take RSTA low. With DAF held low, take RSTA high. This defines AF/AEA using X. To retain the current offset for the next reset, keep DAF low. default X To redefine AF/AE using the default value of X = 256, hold DAF high during the reset cycle.Figure 1 |
Аналогичный номер детали - SN74ACT2235-20FN |
|
Аналогичное описание - SN74ACT2235-20FN |
|
|
ссылки URL |
Конфиденциальность |
ALLDATASHEETRU.COM |
Вашему бизинису помогли Аллдатащит? [ DONATE ] |
Что такое Аллдатащит | реклама | контакт | Конфиденциальность | обмен ссыками | поиск по производителю All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |