HYB18M1G320BF Datasheet, PDF (14/62 Pages) Qimonda AG – DRAMs for Mobile Applications 1-Gbit x32 DDR Mobile-RAM

Data Sheet
HY[B/E]18M1G320BF
1-Gbit DDR Mobile-RAM
2.2.2.1 Partial Array Self Refresh (PASR)
Partial Array Self Refresh is a power-saving feature specific to DDR 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,
and a quarter of one bank. Data written to the non activated memory sections will get lost after a period defined by t_REF (cf.
Table 14).
2.2.2.2
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, and low temperatures correspond to long refresh periods.
The DDR 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. It also 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, e.g. because of the lack of an
external temperature sensor
• it does not require any processor interaction for regular TCSR updates
2.2.2.3 Selectable Drive Strength
The drive strength of the DQ output buffers is selectable via bits A5 and A6. The “full drive strength” (default) is suitable for
heavier loaded systems. The “half drive strength” is intended for lightly loaded systems or systems with reduced performance
requirements. For systems with point-to-point connection, a “quarter drive strength” is available. I-V curves for full and half drive
strengths are included in this document.
Rev.1.00, 2007-03
14
02022006-J7N7-GYFP