W632GU6NB
Publication Release Date: Aug. 20, 2018
Revision: A01
- 83 -
8.19.2.3 ODT during Reads
As the DDR3L SDRAM cannot terminate and drive at the same time, R
TT
must be disabled at least half a clock cycle before the read preamble by driving
the ODT pin low appropriately. R
TT
may not be enabled until the end of the post-amble as shown in the example below. As shown in Figure 76 below, at
cycle T15, DRAM turns on the termination when it stops driving, which is determined by t
HZ
. If DRAM stops driving early (i.e., t
HZ
is early), then t
AON
min
timing may apply. If DRAM stops driving late (i.e., t
HZ
is late), then DRAM complies with t
AON
max timing. Note that ODT may be disabled earlier before the
Read and enabled later after the Read than shown in this example in Figure 76.
T0
T1
T2
T4
CK#
CK
T5
T3
ODT
T6
T7
T8
T9
T10
T12
T13
T14
T15
T11
READ
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
T16
t
AOFmin
Command
ODTTLoff = CWL + AL - 2
ODTLon = CWL + AL - 2
RL = AL + CL
VALID
Rtt_Nom
NOP
T17
NOP
NOP
NOP
Dout
b
Dout
b+2
Dout
b+3
Dout
b+1
Dout
b+5
Dout
b+6
Dout
b+4
Dout
b+7
t
AOFmax
t
AONmax
Rtt_Nom
NOP
NOP
RTT
DQS, DQS#
DQ
TRANSITIONING
DON'T CARE
Address
Figure 76
– ODT must be disabled externally during Reads by driving ODT low.
(CL = 6; AL = CL - 1 = 5; RL = AL + CL = 11; CWL = 5; ODTLon = CWL + AL - 2 = 8; ODTLoff = CWL + AL - 2 = 8)