CMS4A16LAH datasheet(11/46 Pages) FIDELIX

11 / 46 page

Rev. 0.5, May. ‘07

CMS4A16LAx–75Ex

≤ 133

≤ 100

≤ 50

133MHz

CAS Latency = 1

≤ 100

≤ 83

≤ 40

100MHz

CAS Latency = 3

CAS Latency = 2

Allowable Operating Frequency (MHz)

Speed

Table 3. CAS Latency.

EXTENDED MODE REGISTER

The Extended Mode Register controls additional functions such

as Partial Array Self Refresh (PASR) and Driver Strength (DS).

The Extended Mode Register is programmed via the Mode

information until it is programmed again or the device loses

power. The Extended Mode Register must be programmed with

M8 through M11 set to “0”. The Extended Mode Register must

be loaded when all banks are idle and no bursts are in progress,

and the controller must wait the specified time initiating any

subsequent operation. Violating either of these requirements

results in unspecified operation.

AUTO TEMPERATURE COMPENSATED SELF REFRESH

Every cell in the DRAM requires refreshing due to the capacitor

losing its charge over time. The refresh rate is dependent on

temperature. At higher temperatures a capacitor loses charge

quicker than at lower temperatures, requiring the cells to be

refreshed more often. In order to save power consumption,

according to the temperature, Mobile-SDRAM includes the

internal temperature sensor and control units to control the self

refresh cycle automatically.

PARTIAL ARRAY SELF REFRESH

The Partial Array Self Refresh (PASR) feature allows the con-

troller to select the amount of memory that will be refreshed

during SELF REFRESH. The refresh options are all banks

(banks 0, 1, 2, and 3); two banks(banks 0 and 1 or 2 and 3 by

M7); and one bank (bank 0 or 2 by M7). WRITE and READ

commands occur to any bank selected during standard

operation, but only the selected banks in PASR will be

refreshed during SELF REFRESH. The data in the deselected

bank will be lost.

Driver Strength Control

The driver strength feature allows one to reduce the

drive strength of the I/O’s on the device during low frequency

operation. This allows systems to reduce the noise associated

with the I/O’s switching.

Bank

Up/Down

All must be set to ‘0’

Driver Strength

EM6-

EM5-

EM4-

EM3-

PASR

EM2-

EM1-

EM9-

EM8-

EM7-

EM0-

EM10-

A10

EM11-

A11

EM12-

BA0

EM13-

BA1

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