HYB18L128160BF Datasheet, PDF (15/53 Pages) Infineon Technologies AG – DRAMs for Mobile Applications

HY[B/E]18L128160B[C/F]-7.5
128-Mbit Mobile-RAM
Functional Description
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, and 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. 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
2.2.1.8 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 the full drive strength and half drive strength are included in this document.
Data Sheet
15
V1.4, 2004-04-30