
September 15, 2005 S71WS-N_01_A4
S71WS-Nx0 Based MCPs
151
A d v a n c e I n f o r m a t i o n
Note:
Default mode. The address bits other than those listed in the table above are reserved. For example, Burst Length
address bits(A7:A6:A5) have 4 sets of reserved bits like 0:0:0, 0:0:1, 1:0:1 and 1:1:0. If the reserved address bits are input,
then the mode will be set to the default mode. Each field has its own default mode, but this default mode is not 100% guar-
anteed, so the MRS setting sequence is highly recommended after power up. A12 is a reserved bit for future use. A12 must
be set as “0”. Not all the mode settings are tested. Per the mode settings to be tested, please contact Spansion. The 256
word Full page burst mode needs to meet t
BC
(Burst Cycle time) parameter as max. 2500ns.
38.2
MRS Pin Control Type Mode Register Setting Timing
In this device, the MRS pin is used for two purposes. One is to get into the mode register setting
and the other is to execute Partial Array Refresh mode.
To get into the Mode Register Setting, the system must drive the MRS# pin to V
IL
and immediately
(within 0.5μs) issue a write command (drive CS#, ADV#, UB#, LB# and WE# to V
IL
and drive
OE# to V
IH
during valid address). If the subsequent write command (WE# signal input) is not
issued within 0.5μs, then the device may get into the PAR mode.
Figure 38.1 Mode Register Setting Timing (OE# = V
IH
)
Table 38.3 MRS AC Characteristics
Note:
V
CC
= 1.7
–
2.0V, T
A
= -40 to 85°C, Maximum Main Clock Frequency= 66MHz
Partial Array Refresh
PAR Array
PAR Size
A4
1
1
A3
0
1
PAR
A2
0
1
PARA
A1
0
0
1
1
A0
0
1
0
1
PARS
PAR Enable
PAR Disable (note 1)
Bottom Array (note 1)
Top Array
Full Array (note 1)
3/4 Array
1/2 Array
1/4 Array
Parameter List
Symbol
t
MW
t
WU
Speed
Units
ns
ns
Min
0
0
Max
500
—
MRS
MRS# Enable to Register Write Start
End of Write to MRS# Disable
t
WU
Address
WE#
t
WC
t
CW
t
AW
t
BW
t
WP
t
AS
t
MW
CS#
ADV#
MRS#
1
2
3
4
5
6
7
8
9
10
11
12
13
CLK
0
(MRS SETTING TIMING)
1. Clock input is ignored.
UB#, LB#
Register Write Start
Register Write Complete
Register Update Complete