W631GG6KB-15 Datasheet, PDF (46/158 Pages) Winbond – Double Data Rate architecture: two data transfers per clock cycle

W631GG6KB
7.13.2.3 tLZ(DQS), tLZ(DQ), tHZ(DQS), tHZ(DQ) Calculation
tHZ and tLZ 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 tHZ(DQS)
and tHZ(DQ), or begins driving tLZ(DQS), tLZ(DQ). Figure 26 shows a method to calculate the point when
the device is no longer driving tHZ(DQS) and tHZ(DQ), or begins driving tLZ(DQS), tLZ(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 tLZ(DQS), tLZ(DQ), tHZ(DQS), and tHZ(DQ) are defined as
singled ended.
tLZ(DQS): CK – CK# rising crossing at RL - 1
tLZ(DQ): CK – CK# rising crossing at RL
CK
CK#
tLZ
tHZ(DQS), tHZ(DQ) with BL8: CK – CK# rising crossing at RL + 4 nCK
tHZ(DQS), tHZ(DQ) with BC4: CK – CK# rising crossing at RL + 2 nCK
CK
CK#
tHZ
VTT + 2x mV
VTT + x mV
VTT - x mV
VTT - 2x mV
tLZ(DQS), tLZ(DQ)
T1
T2
tLZ(DQS), tLZ(DQ) begin point = 2 * T1 - T2
tHZ(DQS), tHZ(DQ)
T2
T1
VOH - x mV
VOH - 2x mV
VOL + 2x mV
VOL + x mV
tHZ(DQS), tHZ(DQ) end point = 2 * T1 - T2
Figure 26 – tLZ and tHZ method for calculating transitions and endpoints
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Publication Release Date: Feb. 27, 2013
Revision A04