V55C2128164V(T/B)
The V55C2128164V(T/B) is a four bank Synchronous DRAM organized as 4 banks x 2Mbit x 16. The
V55C2128164V(T/B) achieves high speed data transfer rates up to 166 MHz by employing a chip architecture
that prefetches multiple bits and then synchronizes the output data to a system clock
All of the control, address, data input and output circuits are synchronized with the positive edge of an ex-
ternally supplied clock.
Operating the four memory banks in an interleaved fashion allows random access operation to occur at
higher rate than is possible with standard DRAMs. A sequential and gapless data rate of up to 166 MHz is
possible depending on burst length, CAS latency and speed grade of the device.
CILETIV LESO M
Description
Signal Pin Description
Pin
CLK
Type
Input
Signal
Pulse
Polarity
Positive
Edge
Function
The system clock input. All of the SDRAM inputs are sampled on the rising edge of the
clock.
CKE
Input
Level
Active High Activates the CLK signal when high and deactivates the CLK signal when low, thereby
initiates either the Power Down mode or the Self Refresh mode.
Active Low CS enables the command decoder when low and disables the command decoder when
high. When the command decoder is disabled, new commands are ignored but previous
operations continue.
Active Low When sampled at the positive rising edge of the clock, CAS, RAS, and WE define the
command to be executed by the SDRAM.
—
During a Bank Activate command cycle, A0-A11 defines the row address (RA0-RA11)
when sampled at the rising clock edge.
During a Read or Write command cycle, A0-An defines the column address (CA0-CAn)
when sampled at the rising clock edge.CAn depends from the SDRAM organization:
• 8M x 16 SDRAM CA0–CA8.
In addition to the column address, A10(=AP) is used to invoke autoprecharge operation
at the end of the burst read or write cycle. If A10 is high, autoprecharge is selected and
BA0, BA1 defines the bank to be precharged. If A10 is low, autoprecharge is disabled.
During a Precharge command cycle, A10(=AP) is used in conjunction with BA0 and BA1
to control which bank(s) to precharge. If A10 is high, all four banks will BA0 and BA1 are
used to define which bank to precharge.
CS
Input
Pulse
RAS, CAS
WE
A0 - A11
Input
Pulse
Input
Level
BA0,
BA1
DQx
Input
Level
—
Selects which bank is to be active.
Input
Output
Input
Level
—
Data Input/Output pins operate in the same manner as on conventional DRAMs.
LDQM
UDQM
Pulse
Active High The Data Input/Output mask places the DQ buffers in a high impedance state when sam-
pled high. In Read mode, DQM has a latency of two clock cycles and controls the output
buffers like an output enable. In Write mode, DQM has a latency of zero and operates as
a word mask by allowing input data to be written if it is low but blocks the write operation
if DQM is high.
Power and ground for the input buffers and the core logic.
VCC, VSS Supply
VCCQ
VSSQ
Supply
—
—
Isolated power supply and ground for the output buffers to provide improved noise
immunity.
V55C2128164V(T/B) Rev. 1.2 August 2002
4
MOSEL [ MOSEL VITELIC, CORP ]
