Electronic Components Datasheet Search |
|
CY7C4275V Datasheet(PDF) 7 Page - Cypress Semiconductor |
|
CY7C4275V Datasheet(HTML) 7 Page - Cypress Semiconductor |
7 / 24 page CY7C4255V, CY7C4265V CY7C4275V, CY7C4285V Document Number: 38-06012 Rev. *D Page 7 of 24 Programmable Almost Empty/Almost Full Flag The CY7C4255/65/75/85V features programmable Almost Empty and Almost Full Flags. Each flag can be programmed (described in section Programming on page 6) a specific distance from the corresponding boundary flags (Empty or Full). When the FIFO contains the number of words or fewer for which the flags have been programmed, the PAF or PAE is asserted, signifying that the FIFO is either Almost Full or Almost Empty. See Table 3 for a description of programmable flags. When the SMODE pin is tied LOW, the PAF flag signal transition is caused by the rising edge of the write clock and the PAE flag transition is caused by the rising edge of the read clock. Retransmit The retransmit feature is beneficial when transferring packets of data. It enables the receipt of data to be acknowledged by the receiver and retransmitted if necessary. The Retransmit (RT) input is active in the standalone and width expansion modes. The retransmit feature is intended for use when a number of writes equal to or less than the depth of the FIFO have occurred and at least one word has been read since the last RS cycle. A HIGH pulse on RT resets the internal read pointer to the first physical location of the FIFO. WCLK and RCLK may be free running but must be disabled during and tRTR after the retransmit pulse. With every valid read cycle after retransmit, previously accessed data is read and the read pointer is incremented until it is equal to the write pointer. Flags are governed by the relative locations of the read and write pointers and are updated during a retransmit cycle. Data written to the FIFO after activation of RT are transmitted also. The full depth of the FIFO can be repeatedly retransmitted. Width Expansion Configuration The CY7C4255/65/75/85V can be expanded in width to provide word widths greater than 18 in increments of 18. During width expansion mode, all control line inputs are common and all flags are available. Empty (Full) flags must be created by ANDing the Empty (Full) flags of every FIFO. The PAE and PAF flags can be detected from any one device. This technique avoids reading data from, or writing data to the FIFO that is “staggered” by one clock cycle due to the variations in skew between RCLK and WCLK. Figure 2 on page 8 demonstrates a 36-word width by using two CY7C4255/65/75/85Vs. Table 3. Flag Truth Table Number of Words in FIFO FF PAF HF PAE EF 7C4255V – 8 K × 18 7C4265V – 16 K × 18 7C4275V – 32 K × 18 7C4285V – 64 K × 18 0 000 H H H L L 1 to n[2] 1 to n[2] 1 to n[2] 1 to n[2] HH H L H (n+1) to 4096 (n+1) to 8192 (n+1) to 16384 (n+1) to 32768 H H H H H 4097 to (8192–(m+1)) 8193 to (16384 –(m+1)) 16385 to (32768–(m+1)) 32769 to (65536 –(m+1)) H H L H H (8192–m)[3] to 8192 (16384–m)[3] to 16384 (32768–m)[3] to 32767 (65536–m)[3] to 65535 HL LH H 8192 16384 32768 65536 L L L H H Notes 2. n = Empty Offset (Default Values: CY7C4255/65/75/85V n = 127). 3. m = Full Offset (Default Values: CY7C4255/65/75/85V n = 127). [+] Feedback |
Similar Part No. - CY7C4275V |
|
Similar Description - CY7C4275V |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |