Electronic Components Datasheet Search
  English  ▼

Delete All


Preview PDF Download HTML

DS1249W Datasheet(PDF) 2 Page - Dallas Semiconductor

Part No. DS1249W
Description  3.3V 2048kb Nonvolatile SRAM
Download  8 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  DALLAS [Dallas Semiconductor]
Homepage  http://www.dalsemi.com

DS1249W Datasheet(HTML) 2 Page - Dallas Semiconductor

Zoom Inzoom in Zoom Outzoom out
 2 / 8 page
background image
2 of 8
The DS1249 devices execute a read cycle whenever WE (Write Enable) is inactive (high) and CE (Chip
Enable) and OE (Output Enable) are active (low). The unique address specified by the 18 address inputs
(A0 – A17) defines which of the 262,144 bytes of data is accessed. Valid data will be available to the eight
data output drivers within tACC (Access Time) after the last address input signal is stable, providing that
and OE access times are also satisfied. If OE and CE access times are not satisfied, then data access
must be measured from the later-occurring signal ( CE or OE ) and the limiting parameter is either tCO for
or tOE for OE rather than tACC.
The DS1249 executes a write cycle whenever the WE and CE signals are active (low) after address
inputs are stable. The later-occurring falling edge of CE or WE will determine the start of the write cycle.
The write cycle is terminated by the earlier rising edge of CE or WE . All address inputs must be kept
valid throughout the write cycle. WE must return to the high state for a minimum recovery time (tWR)
before another cycle can be initiated. The OE control signal should be kept inactive (high) during write
cycles to avoid bus contention. However, if the output drivers are enabled ( CE and OE active), then WE
will disable the outputs in tODW from its falling edge.
The DS1249W provides full functional capability for VCC greater than 3.0 volts and write protects by
2.8V. Data is maintained in the absence of VCC without any additional support circuitry. The nonvolatile
static RAMs constantly monitor VCC. Should the supply voltage decay, the NV SRAMs automatically
write protects themselves, all inputs become “don’t care,” and all outputs become high impedance. As
VCC falls below approximately 2.5V, a power-switching circuit connects the lithium energy source to
RAM to retain data. During power-up, when VCC rises above approximately 2.5V, the power-switching
circuit connects external VCC to the RAM and disconnects the lithium energy source. Normal RAM
operation can resume after VCC exceeds 3.0V.
Each DS1249 device is shipped from Dallas Semiconductor with its lithium energy source disconnected,
guaranteeing full energy capacity. When VCC is first applied at a level greater than VTP, the lithium
energy source is enabled for battery backup operation.

Html Pages

1  2  3  4  5  6  7  8 

Datasheet Download

Related Electronics Part Number

Part NumberComponents DescriptionHtml ViewManufacturer
DS3050W3.3V Single-Piece 4Mb Nonvolatile SRAM with Clock 1 2 3 4 5 MoreMaxim Integrated Products
DS3045W3.3V Single-Piece 1Mb Nonvolatile SRAM with Clock 1 2 3 4 5 MoreMaxim Integrated Products
DS1265W3.3V 8Mb Nonvolatile SRAM 1 2 3 4 5 MoreDallas Semiconductor
DS1230W3.3V 256k Nonvolatile SRAM 1 2 3 4 5 MoreDallas Semiconductor
DS2065W3.3V Single-Piece 8Mb Nonvolatile SRAM 1 2 3 4 5 MoreMaxim Integrated Products
DS1245W3.3V 1024k Nonvolatile SRAM 1 2 3 4 5 MoreDallas Semiconductor
DS3065W3.3V Single-Piece 8Mb Nonvolatile SRAM with Clock 1 2 3 4 5 MoreMaxim Integrated Products
DS1345W3.3V 1024k Nonvolatile SRAM with Battery Monitor 1 2 3 4 5 MoreDallas Semiconductor
DS1250W3.3V 4096k Nonvolatile SRAM 1 2 3 4 5 MoreDallas Semiconductor
DS1330W3.3V 256K Nonvolatile SRAM with Battery Monitor 1 2 3 4 5 MoreDallas Semiconductor

Link URL

Privacy Policy
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com

Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
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