HY5PS56421LF-E3 Datasheet, PDF (33/35 Pages) Hynix Semiconductor – 256Mb DDR2 SDRAM

HY5PS56421(L)F
HY5PS56821(L)F
HY5PS561621(L)F
19. tRPST end point and tRPRE begin point are not referenced to a specific voltage level but specify when
the device output is no longer driving (tRPST), or begins driving (tRPRE). Below figure shows a method to
calculate these points when the device is no longer driving (tRPST), or begins driving (tRPRE). Below Figure
shows a method to calculate these points when the device is no longer driving (tRPST), or begins driving
(tRPRE) by measuring the signal at two different voltages. The actual voltage measurement points are not
critical as long as the calculation is consistent.
tHZ
tRPST end point
VOH + xmV
VOH + 2xmV
VOL + 1xmV
VOL + 2xmV
tHZ , tRPST end point = 2*T1-T2
VTT + 2xmV
VTT + xmV
VTT -xmV
VTT - 2xmV
tHZ
tRPRE begin point
tLZ , tRPRE begin point = 2*T1-T2
20. Input waveform timing with differential data strobe enabled MR[bit10] =0, is referenced from the input sig-
nal crossing at the V_IH(ac) level to the differential data strobe crosspoint for a rising signal, and from the input
signal crossing at the V_IL(ac) level to the differential data strobe crosspoint for a falling signal applied to the
device under test.
21. Input waveform timing with differential data strobe enabled MR[bit10]=0, is referenced from the input sig-
nal crossing at the V_IH(dc) level to the differential data strobe crosspoint for a rising signal and V_IL(dc) to the
differential data strobe crosspoint for a falling signal applied to the device under test.
Differential Input waveform timing
DQS
DQS
tDS tDH
tDS tDH
VDDQ
VIH(ac)min
VIH(dc)min
VREF(dc)
VIL(dc)max
VIL(ac)max
VSS
22. Input waveform timing is referenced from the input signal crossing at the V_IH(ac) level for a rising signal
and V_IL(ac) for a falling signal applied to the device under test.
23. Input waveform timing is referenced from the input signal crossing at the V_IL(dc) level for a rising signal
and V_IH(dc) for a falling signal applied to the device under test.
Rev 1.0 / July. 2004
33