M65KG512AB datasheet(20/54 Pages) STMICROELECTRONICS

20 / 54 page

Operating modes

M65KG526AB

20/54

Operating modes

There are 7 operating modes that control the memory. Each of these is composed by a

sequence of commands (see Table 6: Operating modes for a summary).

4.1

Power-Up

The DDR LPSDRAM has to be powered up and initialized in a well determined manner:

After applying power to VDD and VDDQ an initial pause of at least 200µs is required

before the signals can be toggled.

The Precharge command must then be issued to all banks. Until the command is

issued KE and UDQM/LDQM must be held High to make sure that DQ0-DQ15 remain

high impedance.

tRP after precharging all the banks, the Mode Register and the Extended Mode

after each register set command.

After the two registers are configured, two or more auto Refresh cycles must be

executed before the device is ready for normal operation.

The third and fourth steps can be swapped.

Refer to Figure 26 for a detailed description of the Power-Up ac waveforms.

4.2

Burst Read

The M65KG512AB is switched in Burst Read mode by issuing a Bank (Row) Activate

command to set the bank and row addresses to be read from, followed by a Read command

(see Section 3.3: Bank(Row) Activate command (ACT) and Section 3.4: Read command

(READ) for details).

Burst Read can be accompanied by an Auto Precharge cycle depending on the state of the

A10 Address Input. If A10 is High (set to ‘1’) when the Burst Read command is issued, the

Burst Read operation will be followed by an Auto Precharge cycle. If A10 is Low (set to ‘0’),

the row will remain active for subsequent accesses.

Burst Read operations are performed at word level only. Different Burst Types (sequential or

interleaved), Burst Lengths (2, 4, 8, and 16 words) can be programmed using the Mode

Section 3.1: Mode Register Set command (MRS), for details on the Mode Register bits and

how to program them.

The Burst Read starts 2t

CK + t

AC after the Clock K rising edge where the Read command is

latched, where t

CK is the Clock period and t

AC is the access time from K or K. Data Strobe,

UDQS/LDQS, are output simultaneously with data. tRPRE prior to the first rising edge of the

data strobe, the UDQS/LDQS signals go from High-Z to Low state. This Low pulse is

referred to as the Read Preamble. The burst data are then output synchronized with the

rising and falling edge of the data strobe. UDQS/LDQS become High-Z on the next clock

cycle after the Burst Read is completed. tRPST from the last falling edge of the data strobe,

the DQS pins become High-Z. This low period of DQS is referred as Read Postamble.

M65KG512AB Datasheet(PDF) 20 Page - STMicroelectronics

M65KG512AB Datasheet(HTML) 20 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

Datasheet Download

Link URL