IBMN312164CT3 IBMN312804CT3
IBMN312404CT3
Preliminary
128Mb Synchronous DRAM - Die Revision B
Pin Description
CK
CKE
Clock Input
Clock Enable
DQ0-DQ15
Data Input/Output
Data Mask
DQM, LDQM, UDQM
CS (CS0, CS1)
RAS
Chip Select
VDD
VSS
VDDQ
VSSQ
NC
Power (+3.3V)
Ground
Row Address Strobe
Column Address Strobe
Write Enable
CAS
Power for DQs (+3.3V)
Ground for DQs
No Connection
—
WE
BS1, BS0
A0 - A11
Bank Select
Address Inputs
—
Input/Output Functional Description
Symbol
Type
Polarity
Function
Positive
Edge
CLK
Input
The system clock input. All of the SDRAM inputs are sampled on the rising edge of the clock.
Activates the CLK signal when high and deactivates the CLK signal when low. By deactivating the
clock, CKE low initiates the Power Down mode, Suspend mode, or the Self Refresh mode.
CKE
Input Active High
CS (CS0, CS1 for stacked devices) enables the command decoder when low and disables the
Input Active Low command decoder when high. When the command decoder is disabled, new commands are
ignored but previous operations continue.
CS, CS0,
CS1
RAS, CAS,
WE
When sampled at the positive rising edge of the clock, CAS, RAS, and WE define the operation to
be executed by the SDRAM.
Input Active Low
BS0, BS1
Input
—
Selects which bank is to be active.
During a Bank Activate command cycle, A0-A11 defines the row address (RA0-RA11) when sam-
pled at the rising clock edge.
During a Read or Write command cycle, A0-A9 and A11 defines the column address (CA0-CA9,
CA11) when sampled at the rising clock edge.
A10 is used to invoke auto-precharge operation at the end of the burst read or write cycle. If A10 is
high, auto-precharge is selected and BS0, BS1 defines the bank to be precharged. If A10 is low,
autoprecharge is disabled.
A0 - A11
Input
—
During a Precharge command cycle, A10 is used in conjunction with BS0, BS1 to control which
bank(s) to precharge. If A10 is high, all banks will be precharged regardless of the state of BS. If
A10 is low, then BS0 and BS1 are used to define which bank to precharge.
Input-
Output
DQ0 - DQ15
—
Data Input/Output pins operate in the same manner as on conventional DRAMs.
The Data Input/Output mask places the DQ buffers in a high impedance state when sampled high.
In x16 products, LDQM and UDQM control the lower and upper byte I/O buffers, respectively. In
Read mode, DQM has a latency of two clock cycles and controls the output buffers like an output
enable. DQM low turns the output buffers on and DQM high turns them off. 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.
DQM
LDQM
UDQM
Input Active High
VDD, VSS
Supply
Supply
—
—
Power and ground for the input buffers and the core logic.
VDDQ VSSQ
Isolated power supply and ground for the output buffers to provide improved noise immunity.
©IBM Corporation. All rights reserved.
06K7582.H03335A
01/01
Use is further subject to the provisions at the end of this document.
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