CMS3216LAH datasheet(6/46 Pages) FIDELIX

6 / 46 page

Rev0.2, Jan. 2007

CMS3216LAx-75xx

FUNCTIONAL DESCRIPTION

The Fidelix 32Mb SDRAM is a dual-bank DRAM that

operates at 2.3~3.3V and includes a synchronous inter-

face (all signals are registered on the positive edge of the

clock signal, CLK). Each of 16,777,216-bit banks is

organized as 2,048 rows by 512 columns by 16 bits. Read

and write accesses to the SDRAM are burst oriented;

accesses start at a selected location and continue for a pro-

grammed number of locations in a programmed sequence.

Accesses begin with the registration of an ACTIVE command,

which is then followed by a READ or WRITE command.

The address bits registered coincident with the ACTIVE

command are used to select the bank and row to be

a c c e s s e d ( B S s e l e c t the ba nk, A0- A 10 select the

row). The address bits (A0-A8) registered coincident with the

READ or WRITE command are used to select the starting

column location for the burst access.The SDRAM must be ini-

tialized prior to normal operation. The following sections pro-

vide detailed information regarding device initialization,

Initialization

SDRAMs must be powered up and initialized in a predefined

manner. Operational procedures other than those specified

may result in undefined operation. Once power is applied to

VDD and VDDQ(simultaneously) and the clock is stable (meets

the clock specifications in the AC characteristics), the SDRAM

requires a 100µs delay prior to issuing any command other than

a COMMAND INHIBIT or NOP. The COMMAND

INHIBIT or

NOP should be applied at least once during the 100µs delay.

After the 100µs delay, a PRECHARGE command should be

applied. All banks must then be precharged, thereby placing the

device in the all banks idle state. Once in the idle state, two

AUTO REFRESH cycles must be performed. After the AUTO

REFRESH cycles are complete, the SDRAM is ready for mode

in an unknown state, it should be loaded prior to applying any

operational command. Refer to Figure 1.

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