V54C316162V
The default power on state of the mode register is
supplier specific and may be undefined. The
following power on and initialization sequence
guarantees the device is preconditioned to each
users specific needs. Like a conventional DRAM,
the Synchronous DRAM must be powered up and
initialized in a predefined manner. During power on,
all VCC and VCCQ pins must be built up
simultaneously to the specified voltage when the
input signals are held in the “NOP” state. The power
on voltage must not exceed VCC+0.3V on any of
the input pins or VCC supplies. The CLK signal
must be started at the same time. After power on,
an initial pause of 200
µs
is required followed by a
precharge of both banks using the precharge
command. To prevent data contention on the DQ
bus during power on, it is required that the DQM and
CKE pins be held high during the initial pause
period. Once all banks have been precharged, the
Mode Register Set Command must be issued to
initialize the Mode Register. A minimum of eight
Auto Refresh cycles (CBR) are also required.These
may be done before or after programming the Mode
Register. Failure to follow these steps may lead to
unpredictable start-up modes.
5
CILETIV LESOM
A9
0
1
A6
0
0
0
0
1
1
1
A5
0
0
1
1
0
1
1
Address Input for Mode Set (Mode Register Operation)
A10 A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
Address Bus (Ax)
Write Burst Length
Test
Mode
CAS Latency
BT
Burst Length
Mode Register
Write Burst Length
Length
Burst
Single Bit
Test Mode
A8
0
A7
0
Mode
Mode Reg
Set
Burst Type
A3
0
1
Type
Sequential
Interleave
CAS Latency
A4
0
1
0
1
1
0
1
Latency
Reserve
Reserve
2
3
Reserve
Reserve
Reserve
Burst Length
Length
A2
0
0
0
0
1
1
1
1
A1
0
0
1
1
0
0
1
1
A0
Sequential
0
1
0
1
0
1
0
1
1
2
4
8
Reserve
Reserve
Reserve
Full Page
Interleave
1
2
4
8
Reserve
Reserve
Reserve
Reserve
Power On and Initialization
Programming the Mode Register
The Mode register designates the operation
mode at the read or write cycle. This register is di-
vided into 4 fields. A Burst Length Field to set the
length of the burst, an Addressing Selection bit to
program the column access sequence in a burst
cycle (interleaved or sequential), a CAS
Latency
Field to set the access time at clock cycle and a Op-
eration mode field to differentiate between normal
operation (Burst read and burst Write) and a special
Burst Read and Single Write mode. The mode set
operation must be done before any activate com-
mand after the initial power up. Any content of the
mode register can be altered by re-executing the
mode set command. All banks must be in pre-
charged state and CKE must be high at least one
clock before the mode set operation. After the mode
register is set, a Standby or NOP command is
required. Low signals of RAS, CAS, and WE at the
positive edge of the clock activate the mode set
operation. Address input data at this timing defines
parameters to be set as shown in the previous table.
V54C316162V Rev. 2.9 September 2001
MOSEL [ MOSEL VITELIC, CORP ]
