W632GU6NB
Publication Release Date: Aug. 20, 2018
Revision: A01
- 48 -
8.13.2.3 t
LZ(DQS)
, t
LZ(DQ)
, t
HZ(DQS)
, t
HZ(DQ)
Calculation
t
HZ
and t
LZ
transitions occur in the same time window as valid data transitions. These parameters are
referenced to a specific voltage level that specifies when the device output is no longer driving t
HZ(DQS)
and t
HZ(DQ)
, or begins driving t
LZ(DQS)
, t
LZ(DQ)
. Figure 26 shows a method to calculate the point when
the device is no longer driving t
HZ(DQS)
and t
HZ(DQ)
, or begins driving t
LZ(DQS)
, t
LZ(DQ)
, by measuring
the signal at two different voltages. The actual voltage measurement points are not critical as long as
the calculation is consistent. The parameters t
LZ(DQS)
, t
LZ(DQ)
, t
HZ(DQS)
, and t
HZ(DQ)
are defined as
singled ended.
V
TT
+ 2x mV
V
TT
+ x mV
V
TT
- x mV
V
TT
- 2x mV
T1
T2
t
LZ
CK
CK#
t
LZ(DQS)
, t
LZ(DQ)
t
LZ(DQS)
: CK
– CK# rising crossing at RL - 1
t
LZ(DQ)
: CK
– CK# rising crossing at RL
t
HZ
CK
CK#
t
HZ(DQS)
, t
HZ(DQ)
with BL8: CK
– CK# rising crossing at RL + 4 nCK
t
HZ(DQS)
, t
HZ(DQ)
with BC4: CK
– CK# rising crossing at RL + 2 nCK
V
OH
- x mV
V
OH
- 2x mV
T2
T1
t
HZ(DQS)
, t
HZ(DQ)
V
OL
+ 2x mV
V
OL
+ x mV
t
HZ(DQS)
, t
HZ(DQ)
end point = 2 * T1 - T2
t
LZ(DQS)
, t
LZ(DQ)
begin point = 2 * T1 - T2
Figure 26
– t
LZ
and t
HZ
method for calculating transitions and endpoints