HY5DU28422ETP Datasheet, PDF (21/35 Pages) Hynix Semiconductor – 128Mb DDR SDRAM

HY5DU28422ETP
HY5DU28822ETP
HY5DU281622ETP
CAS LATENCY
The Read latency, or CAS latency, is the delay, in clock cycles, between the registration of a Read command and the
availability of the first burst of output data. The latency can be programmed 2 / 2.5 / 3 clocks.
If a Read command is registered at clock edge n, and the latency is m clocks, the data is available nominally coincident
with clock edge n + m.
Reserved states should not be used as unknown operation or incompatibility with future versions may result.
DLL RESET
The DLL must be enabled for normal operation. DLL enable is required during power up initialization, and upon return-
ing to normal operation after having disabled the DLL for the purpose of debug or evaluation. The DLL is automatically
disabled when entering self refresh operation and is automatically re-enabled upon exit of self refresh operation. Any
time the DLL is enabled, 200 clock cycles must occur to allow time for the internal clock to lock to the externally
applied clock before an any command can be issued.
OUTPUT DRIVER IMPEDANCE CONTROL
The normal drive strength for all outputs is specified to be SSTL_2, Class II. Hynix also supports a half strength driver
option, intended for lighter load and/or point-to-point environments. Selection of the half strength driver option will
reduce the output drive strength by 50% of that of the full strength driver. I-V curves for both the full strength driver
and the half strength driver are included in this document.
Rev. 0.3 /Apr. 2006
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