 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
IC41LV16257-50KI Datasheet(PDF) 5 Page - Integrated Circuit Solution Inc |
|
||||||||||||||||||||||||||||||
IC41LV16257-50KI Datasheet(HTML) 5 Page - Integrated Circuit Solution Inc |
|
|
5 / 20 page  IC41C16257/IC41C16257S IC41LV16257/IC41LV16257S Integrated Circuit Solution Inc. 5 DR021-0A 08/11/2001 FUNCTIONAL DESCRIPTION The IC41C16257 and the IC41LV16257 are CMOS DRAMs optimized for high-speed bandwidth, low-power applications. During READ or WRITE cycles, each bit is uniquely addressed through the 18 address bits. These are entered nine bits (A0-A8) at a time. The row address is latched by the Row Address Strobe ( RAS). The column address is latched by the Column Address Strobe ( CAS). RAS is used to latch the first nine bits and CAS is used to latch the latter nine bits. The IC41C16257 and the IC41LV16257 have two CAS controls, LCAS and UCAS. The LCAS and UCAS inputs internally generate a CAS signal functioning in an identical manner to the single CAS input on the other 256K x 16 DRAMs. The key difference is that each CAS controls its corresponding I/O tristate logic (in conjunction with OE and WE and RAS). LCAS controls I/O0 - I/O7 and UCAS controls I/O8 - I/O15. The IC41C16257/IC41LV16257 CAS function is determined by the first CAS (LCAS or UCAS) transitioning LOW and the last transitioning back HIGH. The two CAS controls give the IC41C16257 both BYTE READ and BYTE WRITE cycle capabilities. Memory Cycle A memory cycle is initiated by bringing RAS LOW and it is terminated by returning both RAS and CAS HIGH. To ensure proper device operation and data integrity any memory cycle, once initiated, must not be ended or aborted before the minimum tRAS time has expired. A new cycle must not be initiated until the minimum precharge time tRP, tCP has elapsed. Read Cycle A read cycle is initiated by the falling edge of CAS or OE, whichever occurs last, while holding WE HIGH. The column address must be held for a minimum time specified by tAR. Data Out becomes valid only when tRAC, tAA, tCAC and tOE are all satisfied. As a result, the access time is dependent on the timing relationships between these parameters. Write Cycle A write cycle is initiated by the falling edge of CAS and WE, whichever occurs last. The input data must be valid at or before the falling edge of CAS or WE, whichever occurs last. Refresh Cycle To retain data, 512 refresh cycles are required in each 8 ms period. There are two ways to refresh the memory: 1. By clocking each of the 512 row addresses (A0 through A8) with RAS at least once every 8 ms. Any read, write, read-modify-write or RAS-only cycle refreshes the ad- dressed row. 2. Using a CAS-before-RAS refresh cycle. CAS-before- RAS refresh is activated by the falling edge of RAS, while holding CAS LOW. In CAS-before-RAS refresh cycle, an internal 9-bit counter provides the row addresses and the external address inputs are ignored. CAS-before-RAS is a refresh-only mode and no data access or device selection is allowed. Thus, the output remains in the High-Z state during the cycle. Self Refresh Cycle(1) The Self Refresh allows the user a dynamic refresh, data retention mode at the extended refresh period of 64 ms. i.e., 125 µs per row when using distributed CBR refreshes. The feature also allows the user the choice of a fully static, low power data retention mode. The optional Self Refresh feature is initiated by performing a CBR Refresh cycle and holding RAS LOW for the specified tRASS. The Self Refresh mode is terminated by driving RAS HIGH for a minimum time of tRPS. This delay allows for the completion of any internal refresh cycles that may be in process at the time of the RAS LOW-to-HIGH transition. If the DRAM controller uses a distributed refresh sequence, a burst refresh is not required upon exiting Self Refresh. However, if the DRAM controller utilizes a RAS-only or burst refresh sequence, all 512 rows must be refreshed within the average internal refresh rate, prior to the resumption of normal operation. Power-On After application of the VCC supply, an initial pause of 200 µs is required followed by a minimum of eight initialization cycles (any combination of cycles containing a RAS signal). During power-on, it is recommended that RAS track with VCC or be held at a valid VIH to avoid current surges. Note: 1.Self Refresh is for Sversion only. |
Similar Part No. - IC41LV16257-50KI |
|
Similar Description - IC41LV16257-50KI |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
