K4N56163QF Datasheet, PDF (19/73 Pages) Samsung semiconductor – 256Mbit gDDR2 SDRAM

K4N56163QF-GC
256M gDDR2 SDRAM
24. The clock frequency is allowed to change during self–refresh mode or precharge power-down mode. In case of clock frequency
change during precharge power-down, a specific procedure is required as described in gDDR2 device operation
25. ODT turn on time min is when the device leaves high impedance and ODT resistance begins to turn on.
ODT turn on time max is when the ODT resistance is fully on. Both are measured from tAOND.
26. ODT turn off time min is when the device starts to turn off ODT resistance.
ODT turn off time max is when the bus is in high impedance. Both are measured from tAOFD.
27. tHZ and tLZ transitions occur in the same access time as valid data transitions. These parameters are referenced to a specific volt-
age level which specifies when the device output is no longer driving (tHZ), or begins driving (tLZ) . Following figure shows a method to
calculate the point when device is no longer driving (tHZ), or begins driving (tLZ) by measuring the signal at two different voltages. The
actual voltage measurement points are not critical as long as the calculation is consistent.
28. 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). Following 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.
These notes are referenced to the “Timing parameters by speed grade” tables for gDDR2-533/667 and gDDR2-800.
VOH + x mV
VOH + 2x mV
tHZ
tRPST end point
T2
T1
VOL + 2x mV
VOL + x mV
tHZ,tRPST end point = 2*T1-T2
VTT + 2x mV
VTT + x mV
tLZ
tRPRE begin point
VTT - x mV
VTT - 2x mV
T1
T2
tLZ,tRPRE begin point = 2*T1-T2
<Test method for tLZ, tHZ, tRPRE and tRPST>
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Rev 1.6 (Apr. 2005)