Data Sheet.
HY[B/E]18L512160BF-7.5
512-Mbit Mobile-RAM
2.2.1.6
Partial Array Self Refresh (PASR)
Partial Array Self Refresh is a power-saving feature specific to Mobile RAMs. With PASR, self refresh may be restricted to
variable portions of the total array. The selection comprises:
•
•
•
•
•
all four banks (default)
two banks
one bank
half of one bank
a quarter of one bank.
Data written to the non-activated memory sections will get lost after a period defined by tREF (see Table 15).
2.2.1.7
Temperature Compensated Self Refresh (TCSR) with On-
Chip Temperature Sensor
DRAM devices store data as electrical charge in tiny capacitors that require a periodic refresh in order to retain the stored
information. This refresh requirement heavily depends on the die temperature:
•
•
high temperatures correspond to short refresh periods
low temperatures correspond to long refresh periods.
The Mobile-RAM is equipped with an on-chip temperature sensor which continuously senses the actual die temperature and
adjusts the refresh period in Self Refresh mode accordingly. This makes any programming of the TCSR bits in the Extended
Mode Register obsolete. Also, it is the superior solution in terms of compatibility and power-saving, because:
•
it is fully compatible to all processors that do not support the Extended Mode Register
it is fully compatible to all applications that only write a default (worst case) TCSR value (that is, because of the lack of an
external temperature sensor)
•
•
it does not require any processor interaction for regular TCSR updates
2.2.1.8
Selectable Drive Strength
The drive strength of the DQ output buffers is selectable via bits A5 and A6. The default value (“half drive strength”) is
suitable for typical applications of a Mobile-RAM. For heavier loaded systems, a stronger output buffer (“full drive
strength”) is available. I-V curves for full drive strength and half drive strength can be found in this document.
Rev. 1.22, 2006-12
13
01132005-06IU-IGVM
QIMONDA [ QIMONDA AG ]
