 |
数据搜索系统，热门电子元器件搜索 |
|
|
数据搜索系统，热门电子元器件搜索 |
|
EP20K100E 数据表(PDF) 14 Page - Altera Corporation |
|
||||||||||||||||||||||||||||||
EP20K100E 数据表(HTML) 14 Page - Altera Corporation |
|
|
14 / 117 page  14 Altera Corporation APEX 20K Programmable Logic Device Family Data Sheet Each LE has two outputs that drive the local, MegaLAB, or FastTrack Interconnect routing structure. Each output can be driven independently by the LUT’s or register’s output. For example, the LUT can drive one output while the register drives the other output. This feature, called register packing, improves device utilization because the register and the LUT can be used for unrelated functions. The LE can also drive out registered and unregistered versions of the LUT output. The APEX 20K architecture provides two types of dedicated high-speed data paths that connect adjacent LEs without using local interconnect paths: carry chains and cascade chains. A carry chain supports high-speed arithmetic functions such as counters and adders, while a cascade chain implements wide-input functions such as equality comparators with minimum delay. Carry and cascade chains connect LEs 1 through 10 in an LAB and all LABs in the same MegaLAB structure. Carry Chain The carry chain provides a very fast carry-forward function between LEs. The carry-in signal from a lower-order bit drives forward into the higher- order bit via the carry chain, and feeds into both the LUT and the next portion of the carry chain. This feature allows the APEX 20K architecture to implement high-speed counters, adders, and comparators of arbitrary width. Carry chain logic can be created automatically by the Quartus II software Compiler during design processing, or manually by the designer during design entry. Parameterized functions such as library of parameterized modules (LPM) and DesignWare functions automatically take advantage of carry chains for the appropriate functions. The Quartus II software Compiler creates carry chains longer than ten LEs by linking LABs together automatically. For enhanced fitting, a long carry chain skips alternate LABs in a MegaLAB™ structure. A carry chain longer than one LAB skips either from an even-numbered LAB to the next even- numbered LAB, or from an odd-numbered LAB to the next odd- numbered LAB. For example, the last LE of the first LAB in the upper-left MegaLAB structure carries to the first LE of the third LAB in the MegaLAB structure. Figure 6 shows how an n-bit full adder can be implemented in n + 1 LEs with the carry chain. One portion of the LUT generates the sum of two bits using the input signals and the carry-in signal; the sum is routed to the output of the LE. The register can be bypassed for simple adders or used for accumulator functions. Another portion of the LUT and the carry chain logic generates the carry-out signal, which is routed directly to the carry- in signal of the next-higher-order bit. The final carry-out signal is routed to an LE, where it is driven onto the local, MegaLAB, or FastTrack Interconnect routing structures. |
类似零件编号 - EP20K100E |
|
类似说明 - EP20K100E |
|
|
链接网址 |
| 隐私政策 |
| ALLDATASHEETCN.COM |
| ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 链接交换 | 制造商名单 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 |
Chinese ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
