Features: • Organization: 524,288 words × 18 bits
• NTD™ architecture for efficient bus operation
• Fast clock to data access: 7.5/8.5/10 ns
• Fast OE access time: 3.5/4.0 ns
• Fully synchronous operation
• Flow-through mode
• Asynchronous output enable control
• Available in 100-pin TQFP
• Byte write enables
• Clock enable for operation hold
• Multiple chip enables for easy expansion
• 3.3 core power supply
• 2.5V or 3.3V I/O operation with separate VDDQ
• 30 mW typical standby power
• Self-timed write cycles
• Interleaved or linear burst modes
• Snooze mode for standby operationPinout
Specifications
|
Parameter
|
Symbol
|
Min
|
Max
|
Unit
|
| Power supply voltage relative to GND |
VDD, VDDQ |
0.5 |
+4.6 |
V |
| Input voltage relative to GND (input pins) |
VIN |
0.5 |
VDD + 0.5 |
V |
| Input voltage relative to GND (I/O pins) |
VIN |
0.5 |
VDDQ + 0.5 |
V |
| Power dissipation |
PD |
|
1.8 |
W |
| DC output current |
IOUT |
|
50 |
mA |
| Storage temperature (plastic) |
Tstg |
65 |
+150 |
|
| Temperature under bias (Junction) |
Tbias |
65 |
+150 |
|
Description The AS7C33512NTF18A family is a high performance CMOS 8 Mbit Synchronous Static Random Access Memory (Flowthrough SRAM) organized as 524,288 words × 18 bits and incorporates a LATE Write.
This variation of the 8Mb sychronous SRAM uses the No Turnaround Delay (NTD™) architecture, featuring an enhanced write operation that improves bandwidth over pipelined burst devices. In a normal flowthrough burst device, the write data, command, and address are all applied to the device on the same clock edge. If a read command follows AS7C33512NTF18A write command, the system of AS7C33512NTF18A must wait for one 'dead' cycle for valid data to become available. This dead cycle can significantly reduce overall bandwidth for applications requiring random access or readmodify-
write operations.
NTD™ AS7C33512NTF18A devices use the memory bus more efficiently by introducing a write latency that matches one-cycle flow-through read latency. Write data is applied one cycle after the write command and address, allowing the read pipeline to clear. With NTD™, write and read operations can be used in any order without producing dead bus cycles.
Assert R/W low to perform write cycles. Byte write enable controls write access to specific bytes, or can be tied low for full 18 bit writes. Write enable signals, along with the write address, are registered on a rising edge of the clock. Write data is applied to the device one clock cycle later. Unlike some asynchronous SRAMs, output enable OEdoes not need to be toggled for write operations; it can be tied low for normal operations. Outputs go to a high impedance state when the device is de-selected by any of the three chip enable inputs.
Use the ADV (burst advance) input to perform burst read, write and deselect operations. When ADV is high, external addresses, chip select, R/W pins are ignored, and internal address counters increment in the count sequence specified by the LBO control. Any device operations, including burst, can be stalled using the CEN=1, the clock enable input.
The AS7C33512NTF18A operates with a 3.3V ± 5% power supply for the device core (VDD). DQ circuits use a separate power supply (VDDQ) that operates across 3.3V or 2.5V ranges. These devices are available in a 100-pin 14×20 mm TQFP package
AS7C33512NTF18A Data Sheet
