MICRON MT46V32M16TG-75ZL, MT46V32M16TG-8, MT46V32M16TG-8L, MT46V32M16TG-75L, MT46V128M4TG-8L Datasheet

...
ADVANCE
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
66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34
V
SS
DQ15
V
SS
Q
DQ14 DQ13
V
DD
Q
DQ12 DQ11
V
SS
Q
DQ10 DQ9
V
DD
Q
DQ8
NC V
SS
Q
UDQS
DNU
V
REF
V
SS
UDM CK# CK CKE NC
A12 A11 A9 A8 A7 A6 A5 A4
V
SS
x16
VDD
DQ0
VDDQ
DQ1
DQ2
VssQ DQ3
DQ4
VDDQ
DQ5 DQ6
VssQ
DQ7
NC
V
DD
Q
LDQS
NC
VDD
DNU
LDM
WE# CAS# RAS#
CS#
NC
BA0 BA1
A10/AP
A0 A1 A2 A3
VDD
x16
V
SS
DQ7
V
SS
Q NC
DQ6
V
DD
Q NC
DQ5
V
SS
Q NC
DQ4
V
DD
Q NC NC V
SS
Q
DQS
DNU
V
REF
V
SS
DM CK# CK CKE NC
A12 A11 A9 A8 A7 A6 A5 A4
V
SS
x8 x4
V
SS
NC V
SS
Q NC
DQ3
V
DD
Q NC NC V
SS
Q NC
DQ2
V
DD
Q NC NC V
SS
Q
DQS
DNU
V
REF
V
SS
DM CK# CK CKE NC
A12 A11 A9 A8 A7 A6 A5 A4
V
SS
V
DD
DQ0
V
DD
Q
NC
DQ1
V
SS
Q
NC
DQ2
V
DD
Q
NC
DQ3
V
SS
Q NC NC
V
DD
Q NC NC
V
DD
DNU
NC
WE# CAS# RAS#
CS#
NC
BA0 BA1
A10/AP
A0
A1
A2
A3
V
DD
x8x4
V
DD
NC
V
DD
Q
NC
DQ0
V
SS
Q NC NC
V
DD
Q NC
DQ1
V
SS
Q NC NC
V
DD
Q NC NC
V
DD
DNU
NC
WE# CAS# RAS#
CS#
NC
BA0 BA1
A10/AP
A0
A1
A2
A3
V
DD
512Mb: x4, x8, x16
DDR SDRAM
DOUBLE DATA RATE (DDR) SDRAM

FEATURES

•VDD = +2.5V ±0.2V, VDDQ = +2.5V ±0.2V
• Bidirectional data strobe (DQS) transmitted/ received with data, i.e., source-synchronous data capture (x16 has two – one per byte)
• Internal, pipelined double-data-rate (DDR) architecture; two data accesses per clock cycle
• Differential clock inputs (CK and CK#)
• Commands entered on each positive CK edge
• DQS edge-aligned with data for READs; center­aligned with data for WRITEs
• DLL to align DQ and DQS transitions with CK
• Four internal banks for concurrent operation
• Data mask (DM) for masking write data (x16 has two – one per byte)
• Programmable burst lengths: 2, 4, or 8
• x16 has programmable IOL/IOV.
• Concurrent auto precharge option is supported
• Auto Refresh and Self Refresh Modes
• Longer lead TSOP for improved reliability (OCPL)
• 2.5V I/O (SSTL_2 compatible)
MT46V128M4 – 32 Meg x 4 x 4 banks MT46V64M8 – 16 Meg x 8 x 4 banks MT46V32M16 – 8 Meg x 16 x 4 banks
For the latest data sheet revisions, please refer to the Micron Web site: www.micron.com/datasheets

PIN ASSIGNMENT (TOP VIEW)

66-Pin TSOP

OPTIONS MARKING

• Configuration 128 Meg x 4 (32 Meg x 4 x 4 banks) 128M4 64 Meg x 8 (16 Meg x 8 x 4 banks) 64M8 32 Meg x 16 (8 Meg x 16 x 4 banks) 32M16
• Plastic Package – OCPL 66-pin TSOP (standard 22.3mm length) TG (400 mil width, 0.65mm pin pitch)
• Timing – Cycle Time
7.5ns @ CL = 2 (DDR266B)
• Self Refresh
NOTE: 1. Supports PC2100 modules with 2-3-3 timing
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
7.5ns @ CL = 2.5 (DDR266B) 10ns @ CL = 2 (DDR200)
Standard none Low Power L
2. Supports PC2100 modules with 2.5-3-3 timing
3. Supports PC1600 modules with 2-2-2 timing
‡ PRODUCTS AND SPECIFICATIONS DISCUSSED HEREIN ARE FOR EVALUATION AND REFERENCE PURPOSES ONLY AND ARE
1
2
2
-75Z
-75
-8
PRODUCTION DATA SHEET SPECIFICATIONS.
Configuration 32 Meg x 4 x 4 banks 16 Meg x 8 x 4 banks 8 Meg x 16 x 4 banks Refresh Count 8K 8K 8K Row Addressing 8K (A0–A12) 8K (A0–A12) 8K (A0–A12) Bank Addressing 4 (BA0, BA1) 4 (BA0, BA1) 4 (BA0, BA1) Column Addressing 4K (A0–A9, A11, A12) 2K (A0–A9, A1 1) 1K (A0–A9)

KEY TIMING PARAMETERS

SPEED CLOCK RATE DATA-OUT ACCESS DQS-DQ
GRADE CL = 2** CL = 2.5** WINDOW* WINDOW SKEW
-75 133 MHz 133 MHz 2.5ns ±0.75ns +0.5ns
-75 100 MHz 133 MHz 2.5ns ±0.75ns +0.5ns
-8 100 MHz 125 MHz 3.4ns ±0.8ns +0.6ns
*Minimum clock rate @ CL = 2 (-8) and CL = 2.5 (-75) **CL = CAS (Read) Latency
1
128 Meg x 4 64 Meg x 8 32 Meg x 16
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM

512Mb DDR SDRAM PART NUMBERS

(Note: xx= -75, -75Z, or -8)
PART NUMBER CONFIGURATION I/O DRIVE LEVEL REFRESH OPTION
MT46V128M4TG-xx 128 Meg x 4 Full Drive Standard MT46V128M4TG-xxL 128 Meg x 4 Full Drive Low Power
MT46V64M8TG-xx 64 Meg x 8 Full Drive Standard MT46V64M8TG-xxL 64 Meg x 8 Full Drive Low Power
MT46V32M16TG-xx 32 Meg x 16 Programmable Drive Standard MT46V32M16TG-xxL 32 Meg x 16 Programmable Drive Low Power

GENERAL DESCRIPTION

The 512Mb DDR SDRAM is a high-speed CMOS, dynamic random-access memory containing 536,870,912 bits. It is internally configured as a quad­bank DRAM.
The 512Mb DDR SDRAM uses a double data rate architecture to achieve high-speed operation. The double data rate architecture is essentially a 2n- prefetch architecture with an interface designed to transfer two data words per clock cycle at the I/O pins. A single read or write access for the 512Mb DDR SDRAM effectively consists of a single 2n-bit wide, one-clock­cycle data transfer at the internal DRAM core and two corresponding n-bit wide, one-half-clock-cycle data transfers at the I/O pins.
A bidirectional data strobe (DQS) is transmitted ex­ternally, along with data, for use in data capture at the receiver. DQS is a strobe transmitted by the DDR SDRAM during READs and by the memory controller during WRITEs. DQS is edge-aligned with data for READs and center-aligned with data for WRITEs. The x16 offering has two data strobes, one for the lower byte and one for the upper byte.
The 512Mb DDR SDRAM operates from a differen­tial clock (CK and CK#); the crossing of CK going HIGH and CK# going LOW will be referred to as the positive edge of CK. Commands (address and control signals) are registered at every positive edge of CK. Input data is registered on both edges of DQS, and output data is referenced to both edges of DQS, as well as to both edges of CK.
Read and write accesses to the DDR SDRAM are burst oriented; accesses start at a selected location and continue for a programmed number of locations in a programmed sequence. Accesses begin with the regis-
tration 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 accessed. The address bits registered coincident with the READ or WRITE com­mand are used to select the bank and the starting col­umn location for the burst access.
The DDR SDRAM provides for programmable READ or WRITE burst lengths of 2, 4, or 8 locations. An auto precharge function may be enabled to provide a self­timed row precharge that is initiated at the end of the burst access.
As with standard SDR SDRAMs, the pipelined, multibank architecture of DDR SDRAMs allows for con­current operation, thereby providing high effective bandwidth by hiding row precharge and activation time.
An auto refresh mode is provided, along with a power-saving power-down mode. All inputs are com­patible with the JEDEC Standard for SSTL_2. All full drive strength outputs are SSTL_2, Class II compat­ible.
NOTE: 1. The functionality and the timing specifications
discussed in this data sheet are for the DLL-enabled mode of operation.
2. Throughout the data sheet, the various figures and text refer to DQs as “DQ.” The DQ term is to be interpreted as any and all DQ collectively, unless specifically stated otherwise. Additionally, the x16 is divided in to two bytes—the lower byte and upper byte. For the lower byte (DQ0 through DQ7) DM refers to LDM and DQS refers to LDQS; and for the upper byte (DQ8 through DQ15) DM refers to UDM and DQS refers to UDQS.
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
2

TABLE OF CONTENTS

ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
Functional Block Diagram – 128 Meg x 4 ............. 4
Functional Block Diagram – 64 Meg x 8 ............... 5
Functional Block Diagram – 32 Meg x 16 ............. 6
Pin Descriptions ...................................................... 7
Functional Description ......................................... 9
Initialization ...................................................... 9
Register Definition ............................................. 9
Mode Register ............................................... 9
Burst Length ............................................ 9
Burst Type ................................................ 10
Read Latency ........................................... 11
Operating Mode ...................................... 11
Extended Mode Register ............................... 12
DLL Enable/Disable ................................. 12
Commands............................................................ 13
Truth Table 1 (Commands) ....................................... 13
Truth Table 1A (DM Operation) ................................. 13
Deselect .............................................................. 14
No Operation (NOP) .......................................... 14
Load Mode Register ........................................... 14
Active ................................................................ 14
Read ................................................................ 14
Write ................................................................ 14
Precharge ........................................................... 14
Auto Precharge .................................................. 14
Burst Terminate ................................................. 14
Auto Refresh ...................................................... 15
Self Refresh ......................................................... 15
Operation .............................................................. 16
Bank/Row Activation ....................................... 16
Reads ................................................................ 17
Read Burst .................................................... 18
Consecutive Read Bursts .............................. 19
Nonconsecutive Read Bursts ....................... 20
Random Read Accesses ................................ 21
Terminating a Read Burst ............................ 23
Read to Write ............................................... 24
Read to Precharge ......................................... 25
Writes ................................................................ 26
Write Burst .................................................... 27
Consecutive Write to Write ......................... 28
Nonconsecutive Write to Write .................. 29
Random Writes ............................................ 30
Write to Read – Uninterrupting .................. 31
Write to Read – Interrupting ....................... 32
Write to Read – Odd, Interrupting ............. 33
Write to Precharge – Uninterrupting .......... 34
Write to Precharge – Interrupting ............... 35
Write to Precharge – Odd, Interrupting ...... 36
Precharge ........................................................... 37
Power-Down ..................................................... 37
Truth Table 2 (CKE) ................................................. 38
Truth Table 3 (Current State, Same Bank) ..................... 39
Truth Table 4 (Current State, Different Bank) ................. 41
Operating Conditions
Absolute Maximum Ratings .................................... 43
DC Electrical and Operating Conditions ..................... 43
AC Input Operating Conditions ........................... 43
Clock Input Operating Conditions ....................... 44
Capacitance – x4, x8 .............................................. 45
IDD Specifications and Conditions – x4, x8 ........... 45
Capacitance – x16 .................................................. 46
IDD Specifications and Conditions – x16 ............... 46
AC Electrical Characteristics (Timing Table) .......... 47
Slew Rate Derating Table ....................................... 48
Data Valid Window Derating ............................... 52
Voltage and Timing Waveforms
Nominal Output Drive Curves ......................... 53
Reduced Output Drive Curves (x16 only) ........ 54
Output Timing – tDQSQ and tQH - x4, x8 ...... 55
Output Timing – tDQSQ and tQH - x16 .......... 56
Output Timing – tAC and tDQSCK ................. 57
Input Timing ..................................................... 57
Input Voltage .................................................... 58
Initialize and Load Mode Registers .................. 59
Power-Down Mode .......................................... 60
Auto Refresh Mode ........................................... 61
Self Refresh Mode ............................................. 62
Reads
Bank Read - Without Auto Precharge ........ 63
Bank Read - With Auto Precharge .............. 64
Writes
Bank Write – Without Auto Precharge ....... 65
Bank Write – With Auto Precharge ............. 66
Write – DM Operation ................................ 67
66-pin TSOP (TG) dimensions ............................... 68
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
3
A0-A12,
BA0, BA1
WE#
CAS#
RAS#
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
FUNCTIONAL BLOCK DIAGRAM

128 Meg x 4

CKE
CK#
CK
DECODE
COMMAND
MODE REGISTERS
ADDRESS REGISTER
CONTROL
LOGIC
13
REFRESH
COUNTER
13
12
BANK3
BANK2
BANK1
13
ROW-
ADDRESS
MUX
2
2
13
BANK
CONTROL
LOGIC
COLUMN­ADDRESS COUNTER/
LATCH
BANK0
ROW-
ADDRESS
LATCH
&
DECODER
BANK0
8192
11
1
MEMORY
ARRAY
(8,192 x 2,048 x 8)
SENSE AMPLIFIERS
16,384
I/O GATING
DM MASK LOGIC
2048
(x8)
COLUMN DECODER
8
8
4
READ
LATCH
8
DRIVERS
ck
out
CK
WRITE
FIFO
MUX
4
COL0
MASK
&
ck
DATA
in
COL0
4
DQS
GENERATOR
INPUT
REGISTERS
1
1
2
4
8
4
CK
DLL
DATA
DRVRS
1
DQS
1
1
1
RCVRS
4
4
4
1
DQ0 ­DQ3, DM
DQS
CS#
15
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
4
A0-A12,
BA0, BA1
WE#
CAS#
RAS#
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
FUNCTIONAL BLOCK DIAGRAM

64 Meg x 8

CKE
CK#
CK
DECODE
COMMAND
MODE REGISTERS
ADDRESS REGISTER
CONTROL
LOGIC
13
REFRESH
COUNTER
13
11
BANK3
BANK2
BANK1
13
ROW-
ADDRESS
MUX
2
2
13
BANK
CONTROL
LOGIC
COLUMN-
ADDRESS
COUNTER/
LATCH
BANK0
ROW-
ADDRESS
LATCH
&
DECODER
BANK0
8192
10
1
MEMORY
ARRAY
(8192 x 1024 x 16)
SENSE AMPLIFIERS
16,384
I/O GATING
DM MASK LOGIC
1024 (x16)
COLUMN DECODER
16
16
8
READ
LATCH
16
DRIVERS
ck
out
CK
WRITE
FIFO
MUX
8
COL0
MASK
&
ck
DATA
in
COL0
8
DQS
GENERATOR
INPUT
REGISTERS
1
1
2
8
16
8
CK
DLL
DATA
DRVRS
1
DQS
1
1
1
RCVRS
8
8
8
1
DQ0 ­DQ7, DM
DQS
CS#
15
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
5
CKE
CK#
WE#
CAS#
RAS#
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
FUNCTIONAL BLOCK DIAGRAM

32 Meg x 16

CK
CS#
CONTROL
DECODE
COMMAND
LOGIC
REFRESH
COUNTER
13
BANK1
BANK2
BANK3
A0-A12,
BA0, BA1
15
MODE REGISTERS
ADDRESS REGISTER
13
BANK
CONTROL
LOGIC
COLUMN-
ADDRESS
COUNTER/
LATCH
BANK0
ROW-
ADDRESS
LATCH
&
DECODER
9
1
8192
BANK0
MEMORY
ARRAY
(8,192 x 512 x 32)
SENSE AMPLIFIERS
16,384
I/O GATING
DM MASK LOGIC
512
(x32)
COLUMN
DECODER
CK
DLL
32
32
16
READ
LATCH
32
WRITE
DRIVERS
ck
out
CK
FIFO
MUX
16
COL0
MASK
4
&
32
ck
DATA
in
COL0
16
DQS
GENERATOR
INPUT
REGISTERS
2
2
16
16
DATA
DRVRS
2
DQS
2
2
2
16
16
RCVRS
16
2
DQ0 ­DQ15, LDM, UDM
LDQS UDQS
ROW-
ADDRESS
13
13
MUX
2
2
10
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
6
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM

PIN DESCRIPTIONS

TSOP PIN NUMBERS SYMBOL TYPE DESCRIPTION
45, 46 CK, CK# Input Clock: CK and CK# are differential clock inputs. All address and
control input signals are sampled on the crossing of the positive edge of CK and negative edge of CK#. Output data (DQs and DQS) is referenced to the crossings of CK and CK#.
44 CKE Input Clock Enable: CKE HIGH activates and CKE LOW deactivates the
internal clock, input buffers and output drivers. Taking CKE LOW provides PRECHARGE POWER-DOWN and SELF REFRESH operations (all banks idle), or ACTIVE POWER-DOWN (row ACTIVE in any bank). CKE is synchronous for POWER-DOWN entry and exit, and for SELF REFRESH entry. CKE is asynchronous for SELF REFRESH exit and for disabling the outputs. CKE must be maintained HIGH throughout read and write accesses. Input buffers (excluding CK, CK# and CKE) are disabled during POWER­DOWN. Input buffers (excluding CKE) are disabled during SELF REFRESH. CKE is an SSTL_2 input but will detect an LVCMOS LOW level after VDD is applied.
24 CS# Input Chip Select: CS# enables (registered LOW) and disables (regis-
tered HIGH) the command decoder. All commands are masked when CS# is registered HIGH. CS# provides for external bank selection on systems with multiple banks. CS# is considered part of the command code.
23, 22, 21 RAS#, CAS#, Input Command Inputs: RAS#, CAS#, and WE# (along with CS#) define the
WE# command being entered.
47 DM Input Input Data Mask: DM is an input mask signal for write data. Input
20, 47 LDM, UDM data is masked when DM is sampled HIGH along with that input data
during a WRITE access. DM is sampled on both edges of DQS. Although DM pins are input-only, the DM loading is designed to match that of DQ and DQS pins. For the x16 , LDM is DM for DQ0­DQ7 and UDM is DM for DQ8-DQ15. Pin 20 is a NC on x4 and x8
26, 27 BA0, BA1 Input Bank Address Inputs: BA0 and BA1 define to which bank an
ACTIVE, READ, WRITE, or PRECHARGE command is being applied.
29-32, 35-40, A0–A12 Input Address Inputs: Provide the row address for ACTIVE commands, and
28, 41, 42 the column address and auto precharge bit (A10) for READ/WRITE
commands, to select one location out of the memory array in the respective bank. A10 sampled during a PRECHARGE command determines whether the PRECHARGE applies to one bank (A10 LOW, bank selected by BA0, BA1) or all banks (A10 HIGH). The address inputs also provide the op-code during a MODE REGISTER SET command. BA0 and BA1 define which mode register (mode register or extended mode register) is loaded during the LOAD MODE REGISTER command.
2, 4, 5, 7, 8, 10, 11, 13, DQ0–15 I/O Data Input/Output: Data bus for x16 (4, 7, 10, 13, 54, 57, 60, and 63
54, 56, 57, 59, 60, 62, are NC for x8), (2, 4, 7, 8,10, 13, 54, 57, 59, 60, 63, and 65 for x4).
63, 65
(continued on next page)
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
7
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
PIN DESCRIPTIONS (continued)
TSOP PIN NUMBERS SYMBOL TYPE DESCRIPTION
2, 5, 8, 11, 56, 59, 62, 65 DQ0-7 I/O Data Input/Output: Data bus for x8 (2, 8, 59 and 65 are NC for x4).
5, 11, 56, 62 DQ0-3 I/O Data Input/Output: Data bus for x4.
51 DQS I/O Data Strobe: Output with read data, input with write data. DQS is
16, 51 LDQS, UDQS edge-aligned with read data, centered in write data. It is used to
capture data. For the x16 , LDQS is DQS for DQ0-DQ7 and UDQS is DQS for DQ8-DQ15. Pin 16 is NC on x4 and x8.
50 DNU Do Not Use: Must float to minimize noise.
3, 9, 15, 55, 61 V
6, 12, 52, 58, 64 VSSQ Supply DQ Ground. Isolated on the die for improved noise immunity.
1, 18, 33 VDD Supply Power Supply: +2.5V ±0.2V.
34, 48, 66 VSS Supply Ground.
49 VREF Supply SSTL_2 reference voltage.
14, 17, 19, 25, 43, 53 NC No Connect: These pins should be left unconnected.
DDQ Supply DQ Power Supply: +2.5V ±0.2V. Isolated on the die for improved
noise immunity.

RESERVED NC PINS

TSOP PIN NUMBERS SYMBOL TYPE DESCRIPTION
17 A13 I Address input for 1Gb devices.
NOTE: 1. NC pins not listed may also be reserved for other uses now or in the future. This table simply defines specific NC pins deemed to be of importance.
1
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
8

FUNCTIONAL DESCRIPTION

The 512Mb DDR SDRAM is a high-speed CMOS, dynamic random-access memory containing 536,870,912 bits. The 512Mb DDR SDRAM is internally configured as a quad-bank DRAM.
The 512Mb DDR SDRAM uses a double data rate architecture to achieve high-speed operation. The double data rate architecture is essentially a 2n- prefetch architecture, with an interface designed to transfer two data words per clock cycle at the I/O pins. A single read or write access for the 512Mb DDR SDRAM consists of a single 2n-bit wide, one-clock-cycle data transfer at the internal DRAM core and two correspond­ing n-bit wide, one-half-clock-cycle data transfers at the I/O pins.
Read and write accesses to the DDR SDRAM are burst oriented; accesses start at a selected location and continue for a programmed 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 accessed (BA0, BA1 select the bank; A0-A12 select the row). The address bits registered coincident with the READ or WRITE com­mand are used to select the starting column location for the burst access.
Prior to normal operation, the DDR SDRAM must be initialized. The following sections provide detailed in­formation covering device initialization, register defi­nition, command descriptions and device operation.

Initialization

DDR SDRAMs must be powered up and initialized in a predefined manner. Operational procedures other than those specified may result in undefined opera­tion. Power must first be applied to VDD and VDDQ simul­taneously, and then to VREF (and to the system VTT). VTT must be applied after VDDQ to avoid device latch-up, which may cause permanent damage to the device. VREF can be applied any time after VDDQ but is expected to be nominally coincident with VTT. Except for CKE, inputs are not recognized as valid until after VREF is applied. CKE is an SSTL_2 input but will detect an LVCMOS LOW level after VDD is applied. Maintaining an LVCMOS LOW level on CKE during power-up is re­quired to ensure that the DQ and DQS outputs will be in the High-Z state, where they will remain until driven in normal operation (by a read access). After all power supply and reference voltages are stable, and the clock is stable, the DDR SDRAM requires a 200µs delay prior to applying an executable command.
Once the 200µs delay has been satisfied, a DESE-
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
LECT or NOP command should be applied, and CKE should be brought HIGH. Following the NOP command, a PRECHARGE ALL command should be applied. Next a LOAD MODE REGISTER command should be issued for the extended mode register (BA1 LOW and BA0 HIGH) to enable the DLL, followed by another LOAD MODE REGISTER command to the mode register (BA0/ BA1 both LOW) to reset the DLL and to program the operating parameters. Two-hundred clock cycles are required between the DLL reset and any READ com­mand. A PRECHARGE ALL command should then be applied, placing the device in the all banks idle state.
Once in the idle state, two AUTO REFRESH cycles must be performed (tRFC must be satisfied.) Addition­ally, a LOAD MODE REGISTER command for the mode register with the reset DLL bit deactivated (i.e., to pro­gram operating parameters without resetting the DLL) is required. Following these requirements, the DDR SDRAM is ready for normal operation.

Register Definition

MODE REGISTER

The mode register is used to define the specific mode of operation of the DDR SDRAM. This definition includes the selection of a burst length, a burst type, a CAS latency and an operating mode, as shown in Fig­ure 1. The mode register is programmed via the MODE REGISTER SET command (with BA0 = 0 and BA1 = 0) and will retain the stored information until it is pro­grammed again or the device loses power (except for bit A8, which is self-clearing).
Reprogramming the mode register will not alter the contents of the memory, provided it is performed cor­rectly. The mode register must be loaded (reloaded) when all banks are idle and no bursts are in progress, and the controller must wait the specified time before initiating the subsequent operation. Violating either of these requirements will result in unspecified opera­tion.
Mode register bits A0-A2 specify the burst length, A3 specifies the type of burst (sequential or inter­leaved), A4-A6 specify the CAS latency, and A7-A12 specify the operating mode.

Burst Length

Read and write accesses to the DDR SDRAM are burst oriented, with the burst length being program­mable, as shown in Figure 1. The burst length deter­mines the maximum number of column locations that can be accessed for a given READ or WRITE command. Burst lengths of 2, 4, or 8 locations are available for both
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
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512Mb: x4, x8, x16
DDR SDRAM
the sequential and the interleaved burst types.
Reserved states should not be used, as unknown operation or incompatibility with future versions may result.
When a READ or WRITE command is issued, a block of columns equal to the burst length is effectively se­lected. All accesses for that burst take place within this block, meaning that the burst will wrap within the block if a boundary is reached. The block is uniquely se­lected by A1-Ai when the burst length is set to two, by A2-Ai when the burst length is set to four and by A3-Ai when the burst length is set to eight (where Ai is the most significant column address bit for a given con-
0
0
-
A7
7
M6
M9M10M12 M11
0
0
0
0
-
-
A6 A5 A4
654
M4
M5
0
0
0
1
0
0
0
1
0
1
1
0
0
0
1
1
0
1
0
1
1
1
1
1
M7
M8
0
0
1
0
-
-
A3A8A2A1A0
38210
Burst LengthCAS Latency BT0*
M1
M0
M2
0
0
0
0
1
0
1
0
0
1
1
0
0
0
1
0
1
1
1
0
1
1
1
1
M3
0
1
M6-M0
Valid
Valid
-
Burst Type
Sequential
Interleaved
CAS Latency
Reserved
Reserved
2
Reserved
Reserved
Reserved
2.5
Reserved
Operating Mode
Normal Operation
Normal Operation/Reset DLL
All other states reserved
Address Bus
Mode Register (Mx)
Burst Length
M3 = 0
Reserved
Reserved
Reserved
Reserved
Reserved
M3 = 1
Reserved
2
4
8
2
4
8
Reserved
Reserved
Reserved
Reserved
BA1
BA0
130*14
* M14 and M13 (BA0 and BA1)
must be 0, 0 to select the
base mode register (vs. the
extended mode register).
A10
A12 A11
11
10
12
Operating Mode
A9
9
0
0
-
Figure 1
Mode Register Definition
figuration). The remaining (least significant) address bit(s) is (are) used to select the starting location within the block. The programmed burst length applies to both READ and WRITE bursts.

Burst Type

Accesses within a given burst may be programmed to be either sequential or interleaved; this is referred to as the burst type and is selected via bit M3.
The ordering of accesses within a burst is deter­mined by the burst length, the burst type and the start­ing column address, as shown in Table 1.
Table 1
Burst Definition
Burst Starting Column Order of Accesses Within a Burst
Length Address Type = Sequential Type = Interleaved
A0
2
4
A2 A1 A0
0 0 0 0-1-2-3-4-5-6-7 0-1-2-3-4-5-6-7 0 0 1 1-2-3-4-5-6-7-0 1-0-3-2-5-4-7-6 0 1 0 2-3-4-5-6-7-0-1 2-3-0-1-6-7-4-5
8
0 1 1 3-4-5-6-7-0-1-2 3-2-1-0-7-6-5-4 1 0 0 4-5-6-7-0-1-2-3 4-5-6-7-0-1-2-3 1 0 1 5-6-7-0-1-2-3-4 5-4-7-6-1-0-3-2 1 1 0 6-7-0-1-2-3-4-5 6-7-4-5-2-3-0-1 1 1 1 7-0-1-2-3-4-5-6 7-6-5-4-3-2-1-0
NOTE: 1. For a burst length of two, A1-Ai select the two-
data-element block; A0 selects the first access within the block.
2. For a burst length of four, A2-Ai select the four­data-element block; A0-A1 select the first access within the block.
3. For a burst length of eight, A3-Ai select the eight­data-element block; A0-A2 select the first access within the block.
4. Whenever a boundary of the block is reached within a given sequence above, the following access wraps within the block.
0 0-1 0-1 1 1-0 1-0
A1 A0
0 0 0-1-2-3 0-1-2-3 0 1 1-2-3-0 1-0-3-2 1 0 2-3-0-1 2-3-0-1 1 1 3-0-1-2 3-2-1-0
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
10
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM

Read Latency

The READ latency is the delay, in clock cycles, be­tween the registration of a READ command and the availability of the first bit of output data. The latency can be set to 2, or 2.5 clocks, as shown in Figure 2.
If a READ command is registered at clock edge n, and the latency is m clocks, the data will be available nominally coincident with clock edge n + m. Table 2 indicates the operating frequencies at which each CAS latency setting can be used.
Reserved states should not be used as unknown operation or incompatibility with future versions may result.
CK#
CK
COMMAND
DQS
DQ
CK#
CK
COMMAND
DQS
DQ
T0 T1 T2 T2n T3 T3n
READ NOP NOP NOP
CL = 2
T0 T1 T2 T2n T3 T3n
READ NOP NOP NOP
CL = 2.5
Table 2
CAS Latency (CL)
ALLOWABLE OPERATING
FREQUENCY (MHz)
SPEED CL = 2 CL = 2.5
-75Z 75 f 133 75 f 133
-75 75f 100 75 f 133
-8 75f 100 75 ≤ f 125
Operating Mode
The normal operating mode is selected by issuing a MODE REGISTER SET command with bits A7-A12 each set to zero, and bits A0-A6 set to the desired values. A DLL reset is initiated by issuing a MODE REGISTER SET command with bits A7 and A9-A12 each set to zero, bit A8 set to one, and bits A0-A6 set to the desired values. Although not required by the Micron device, JEDEC specifications recommend when a LOAD MODE REGISTER command is issued to reset the DLL, it should always be followed by a LOAD MODE REGIS­TER command to select normal operating mode.
All other combinations of values for A7-A12 are re­served for future use and/or test modes. Test modes and reserved states should not be used because un­known operation or incompatibility with future ver­sions may result.
Burst Length = 4 in the cases shown Shown with nominal tAC and nominal tDSDQ
DON’T CARETRANSITIONING DATA
Figure 2
CAS Latency
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11

EXTENDED MODE REGISTER

Operating Mode
Reserved
Reserved
0–0
Valid
0
1
DLL
Enable
Disable
DLL
110
1
A9
A7
A6 A5 A4
A3A8A2A1A0
Extended Mode Register (Ex)
Address Bus
9
7
654
38210
E0
0
1
Drive Strength
Normal
Reduced
E1
2
0
QFC# Function
Disabled
Reserved
E2
3
E0
E1,
Operating Mode
A10
A11A12
BA1
BA0
10
11
12
1314
NOTE: 1. E14 and E13 (BA0 and BA1) must be 1, 0 to select the
Extended Mode Register (vs. the base Mode Register).
2. The reduced drive strength option is not supported on the x4 and x8 versions, and is only available on the x16 version.
3. The QFC# option is not supported.
E2,E3E4
0–0–0–0
0
E6E5E7E8E9
0–0
E10E11
0
E12
DS
QFC#
The extended mode register controls functions be­yond those controlled by the mode register; these ad­ditional functions are DLL enable/disable and output drive strength. These functions are controlled via the bits shown in Figure 3. The extended mode register is programmed via the LOAD MODE REGIS­TER command to the mode register (with BA0 = 1 and BA1 = 0) and will retain the stored information until it is programmed again or the device loses power. The en­abling of the DLL should always be followed by a LOAD MODE REGISTER command to the mode register (BA0/ BA1 both LOW) to reset the DLL.
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 before initiat­ing any subsequent operation. Violating either of these requirements could result in unspecified operation.
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM

Output Drive Strength

The normal drive strength for all outputs are speci­fied to be SSTL2, Class II. The x16 supports an option for reduced drive. This option is intended for the sup­port of the lighter load and/or point-to-point environ­ments. The selection of the reduced drive strength will alter the DQs and DQSs from SSTL2, Class II drive strength to a reduced drive strength, which is approxi­mately 54% of the SSTL2, Class II drive strength.
The Micron (32Meg x16) device supports a programmable drive strength option.

DLL Enable/Disable

The DLL must be enabled for normal operation. DLL enable is required during power-up initialization and upon returning to normal operation after having disabled the DLL for the purpose of debug or evalua­tion. (When the device exits self refresh mode, the DLL is enabled automatically.) Any time the DLL is enabled, 200 clock cycles must occur before a READ command can be issued.
Figure 3
Extended Mode Register Definition
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
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DDR SDRAM

COMMANDS

Truth Table 1 provides a quick reference of avail­able commands. This is followed by a verbal descrip­tion of each command. Two additional Truth Tables
TRUTH TABLE 1 – COMMANDS
(Note: 1)
NAME (FUNCTION) CS# RAS# CAS# WE# ADDR NOTES
DESELECT (NOP) H X X X X 9
NO OPERATION (NOP) L H H H X 9
ACTIVE (Select bank and activate row) L L H H Bank/Row 3
READ (Select bank and column, and start READ burst) L H L H Bank/Col 4
WRITE (Select bank and column, and start WRITE burst) L H L L Bank/Col 4
BURST TERMINATE L H H L X 8
PRECHARGE (Deactivate row in bank or banks) L L H L Code 5
AUTO REFRESH or SELF REFRESH L L L H X 6, 7 (Enter self refresh mode)
LOAD MODE REGISTER L L L L Op-Code 2
appear following the Operation section; these tables provide current state/next state information.
TRUTH TABLE 1A – DM OPERATION
(Note: 10)
NAME (FUNCTION) DM DQs NOTES
Write Enable L Valid
Write Inhibit HX
NOTE: 1. CKE is HIGH for all commands shown except SELF REFRESH.
2. BA0-BA1 select either the mode register or the extended mode register (BA0 = 0, BA1 = 0 select the mode register; BA0 = 1, BA1 = 0 select extended mode register; other combinations of BA0-BA1 are reserved). A0-A12 provide the op­code to be written to the selected mode register.
3. BA0-BA1 provide bank address and A0-A12 provide row address.
4. BA0-BA1 provide bank address; A0-Ai provide column address (where i = 9 for x16, 9,11 for x8, and 9, 11, 12 for x4); A10 HIGH enables the auto precharge feature (nonpersistent), and A10 LOW disables the auto precharge feature.
5. A10 LOW: BA0-BA1 determine which bank is precharged. A10 HIGH: all banks are precharged and BA0-BA1 are “Don’t Care.
6. This command is AUTO REFRESH if CKE is HIGH, SELF REFRESH if CKE is LOW.
7. Internal refresh counter controls row addressing; all inputs and I/Os are “Don’t Care except for CKE.
8. Applies only to read bursts with auto precharge disabled; this command is undefined (and should not be used) for READ bursts with auto precharge enabled and for WRITE bursts.
9. DESELECT and NOP are functionally interchangeable.
10. Used to mask write data; provided coincident with the corresponding data.
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13

DESELECT

The DESELECT function (CS# HIGH) prevents new commands from being executed by the DDR SDRAM. The DDR SDRAM is effectively deselected. Operations already in progress are not affected.

NO OPERATION (NOP)

The NO OPERATION (NOP) command is used to instruct the selected DDR SDRAM to perform a NOP (CS# LOW). This prevents unwanted commands from being registered during idle or wait states. Operations already in progress are not affected.

LOAD MODE REGISTER

The mode registers are loaded via inputs A0–A12. See mode register descriptions in the Register Defini­tion section. The LOAD MODE REGISTER command can only be issued when all banks are idle, and a subse­quent executable command cannot be issued until
t
MRD is met.

ACTIVE

The ACTIVE command is used to open (or activate) a row in a particular bank for a subsequent access. The value on the BA0, BA1 inputs selects the bank, and the address provided on inputs A0–A12 selects the row. This row remains active (or open) for accesses until a PRECHARGE command is issued to that bank. A PRECHARGE command must be issued before open­ing a different row in the same bank.

READ

The READ command is used to initiate a burst read access to an active row. The value on the BA0, BA1 inputs selects the bank, and the address provided on inputs A0–Ai (where i = 9 for x16; 9, 11 for x8; or 9, 11, and 12 for x4) selects the starting column location. The value on input A10 determines whether or not auto precharge is used. If auto precharge is selected, the row being accessed will be precharged at the end of the READ burst; if auto precharge is not selected, the row will remain open for subsequent accesses.

WRITE

The WRITE command is used to initiate a burst write access to an active row. The value on the BA0, BA1 inputs selects the bank, and the address provided on inputs A0–Ai (where i = 9 for x16; 9 and 11 for x8; or 9, 11, and 12 for x4) selects the starting column location. The value on input A10 determines whether or not auto precharge is used. If auto precharge is selected, the row being ac­cessed will be precharged at the end of the WRITE burst; if auto precharge is not selected, the row will remain open for subsequent accesses. Input data
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
appearing on the DQs is written to the memory array subject to the DM input logic level appearing coincident with the data. If a given DM signal is registered LOW, the corresponding data will be written to memory; if the DM signal is registered HIGH, the corresponding data in­puts will be ignored, and a WRITE will not be executed to that byte/column location.

PRECHARGE

The PRECHARGE command is used to deactivate the open row in a particular bank or the open row in all banks. The bank(s) will be available for a subsequent row access a specified time (tRP) after the precharge command is issued. Except in the case of concurrent auto precharge, where a READ or WRITE command to a different bank is allowed as long as it does not interrupt the data transfer in the current bank and does not violate any other timing parameters. Input A10 determines whether one or all banks are to be precharged, and in the case where only one bank is to be precharged, inputs BA0, BA1 select the bank. Other­wise BA0, BA1 are treated as “Don’t Care.” Once a bank has been precharged, it is in the idle state and must be activated prior to any READ or WRITE commands being issued to that bank. A PRECHARGE command will be treated as a NOP if there is no open row in that bank (idle state), or if the previously open row is already in the process of precharging.

AUTO PRECHARGE

Auto precharge is a feature which performs the same individual-bank precharge function described above, but without requiring an explicit command. This is accomplished by using A10 to enable auto precharge in conjunction with a specific READ or WRITE command. A precharge of the bank/row that is addressed with the READ or WRITE command is auto­matically performed upon completion of the READ or WRITE burst. Auto precharge is nonpersistent in that it is either enabled or disabled for each individual Read or Write command. This device supports concurrent auto precharge if the command to the other bank does not interrupt the data transfer to the current bank.
Auto precharge ensures that the precharge is initi­ated at the earliest valid stage within a burst. This “earliest valid stage” is determined as if an explicit PRECHARGE command was issued at the earliest pos­sible time, without violating tRAS (MIN), as described for each burst type in the Operation section of this data sheet. The user must not issue another command to the
same bank until the precharge time (tRP) is completed.
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
14

BURST TERMINATE

The BURST TERMINATE command is used to trun­cate READ bursts (with auto precharge disabled). The most recently registered READ command prior to the BURST TERMINATE command will be truncated, as shown in the Operation section of this data sheet. The open page which the READ burst was terminated from remains open.

AUTO REFRESH

AUTO REFRESH is used during normal operation of the DDR SDRAM and is analogous to CAS#-BEFORE­RAS# (CBR) REFRESH in FPM/EDO DRAMs. This com­mand is nonpersistent, so it must be issued each time a refresh is required.
The addressing is generated by the internal refresh controller. This makes the address bits a “Don’t Care” during an AUTO REFRESH command. The 512Mb DDR SDRAM requires AUTO REFRESH cycles at an average interval of 7.8125µs (maximum).
To allow for improved efficiency in scheduling and switching between tasks, some flexibility in the abso­lute refresh interval is provided. A maximum of eight AUTO REFRESH command can be posted to any given DDR SDRAM, meaning that the maximum absolute interval between any AUTO REFRESH command and the next AUTO REFRESH command is 9 × 7.8125µs (70.3µs). This maximum absolute interval is to allow
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
future support for DLL updates internal to the DDR SDRAM to be restricted to AUTO REFRESH cycles, with­out allowing excessive drift in tAC between updates.
Although not a JEDEC requirement, to provide for future functionality features, CKE must be active (High) during the AUTO REFRESH period. The AUTO REFRESH period begins when the AUTO REFRESH command is registered and ends tRFC later.

SELF REFRESH

The SELF REFRESH command can be used to retain data in the DDR SDRAM, even if the rest of the system is powered down. When in the self refresh mode, the DDR SDRAM retains data without external clocking. The SELF REFRESH command is initiated like an AUTO REFRESH command except CKE is disabled (LOW). The DLL is automatically disabled upon entering SELF RE­FRESH and is automatically enabled upon exiting SELF REFRESH (200 clock cycles must then occur before a READ command can be issued). Input signals except CKE are “Don’t Care” during SELF REFRESH.
The procedure for exiting self refresh requires a se­quence of commands. First, CK must be stable prior to CKE going back HIGH. Once CKE is HIGH, the DDR SDRAM must have NOP commands issued for tXSNR because time is required for the completion of any in­ternal refresh in progress. A simple algorithm for meet­ing both refresh and DLL requirements is to apply NOPs for 200 clock cycles before applying any other com­mand.
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
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512Mb: x4, x8, x16
DDR SDRAM

Operations

BANK/ROW ACTIVATION
Before any READ or WRITE commands can be is­sued to a bank within the DDR SDRAM, a row in that bank must be “opened.” This is accomplished via the ACTIVE command, which selects both the bank and the row to be activated, as shown in Figure 4.
After a row is opened with an ACTIVE command, a READ or WRITE command may be issued to that row, subject to the tRCD specification. tRCD (MIN) should be divided by the clock period and rounded up to the next whole number to determine the earliest clock edge after the ACTIVE command on which a READ or WRITE command can be entered. For example, a tRCD specifi­cation of 20ns with a 133 MHz clock (7.5ns period) re­sults in 2.7 clocks rounded to 3. This is reflected in Figure 5, which covers any case where 2 < tRCD (MIN)/
t
CK 3. (Figure 5 also shows the same case for tRCD; the same procedure is used to convert other specification limits from time units to clock cycles).
A subsequent ACTIVE command to a different row in the same bank can only be issued after the previous active row has been “closed” (precharged). The mini­mum time interval between successive ACTIVE com­mands to the same bank is defined by tRC.
A subsequent ACTIVE command to another bank can be issued while the first bank is being accessed, which results in a reduction of total row-access over­head. The minimum time interval between successive ACTIVE commands to different banks is defined by
t
RRD.
CK#
CK
CKE
HIGH
CS#
RAS#
CAS#
WE#
A0-A12
BA0,1
RA
BA
RA = Row Address BA = Bank Address
Figure 4
Activating a Specific Row in
a Specific Bank
CK#
CK
COMMAND
A0-A12
BA0, BA1
T0 T1 T2 T3 T4 T5 T6 T7
ACT ACT
Row Row
Bank x Bank y
NOP
t
RRD
NOP
NOP
t
RCD
NOP
RD/WR
Col
Bank y
DONT CARE
NOP
Figure 5
Example: Meeting tRCD (tRRD) MIN When 2 < tRCD (tRRD) MIN/tCK
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
16
≤≤
3
≤≤
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM

READs

READ bursts are initiated with a READ command, as shown in Figure 6.
The starting column and bank addresses are pro­vided with the READ command and auto precharge is either enabled or disabled for that burst access. If auto precharge is enabled, the row being accessed is precharged at the completion of the burst. For the ge­neric READ commands used in the following illustra­tions, auto precharge is disabled.
During READ bursts, the valid data-out element from the starting column address will be available fol­lowing the CAS latency after the READ command. Each subsequent data-out element will be valid nominally at the next positive or negative clock edge (i.e., at the next crossing of CK and CK#). Figure 7 shows general timing for each possible CAS latency setting. DQS is driven by the DDR SDRAM along with output data. The initial LOW state on DQS is known as the read preamble; the LOW state coincident with the last data­out element is known as the read postamble.
Upon completion of a burst, assuming no other com­mands have been initiated, the DQs will go High-Z. A detailed explanation of tDQSQ (valid data­out skew), tQH (data-out window hold), the valid data window are depicted in Figure 27. A detailed explana­tion of tDQSCK (DQS transition skew to CK) and tAC (data-out transition skew to CK) is depicted in Figure
28.
Data from any READ burst may be concatenated with or truncated with data from a subsequent READ command. In either case, a continuous flow of data can be maintained. The first data element from the new burst follows either the last element of a completed burst or the last desired data element of a longer burst which is being truncated. The new READ command should be issued x cycles after the first READ com­mand, where x equals the number of desired data ele­ment pairs (pairs are required by the 2n-prefetch ar­chitecture). This is shown in Figure 8. A READ com­mand can be initiated on any clock cycle following a previous READ command. Nonconsecutive read data is shown for illustration in Figure 9. Full-speed random read accesses within a page (or pages) can be performed as shown in Figure 10.
CK#
CK
CKE
CS#
RAS#
CAS#
WE#
x4: A0-A9, A11, A12
x8: A0-A9, A11
x16: A0-A9
x8: A12
x16: A11, A12
A10
BA0,1
CA = Column Address BA = Bank Address EN AP = Enable Auto Precharge DIS AP = Disable Auto Precharge
READ Command
HIGH
CA
EN AP
DIS AP
BA
DONT CARE
Figure 6
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
17
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
CK#
CK
COMMAND
ADDRESS
DQS
DQ
CK#
CK
COMMAND
ADDRESS
T0 T1 T2 T3T2n T3n T4 T5
READ NOP NOP NOP NOP NOP
Bank a,
Col n
CL = 2
DO
n
T0 T1 T2 T3T2n T3n T4 T5
READ NOP NOP NOP NOP NOP
Bank a,
Col n
CL = 2.5
DQS
DQ
NOTE: 1. DO n = data-out from column n.
DO
n
DONT CARE TRANSITIONING DATA
2. Burst length = 4.
3. Three subsequent elements of data-out appear in the programmed order following DO n.
4. Shown with nominal tAC, tDQSCK, and tDQSQ.
Figure 7
READ Burst
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
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ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
CK#
CK
COMMAND
ADDRESS
DQS
DQ
CK#
CK
COMMAND
COMMAND
ADDRESS
ADDRESS
DQS
T0 T1 T2 T3T2n T3n T4 T5T4n T5n
READ NOP READ NOP NOP NOP
Bank,
Col n
Bank,
Col b
CL = 2
DO
n
DO
b
T0 T1 T2 T3T2n T3n T4 T5T4n T5n
READ NOP READ NOP NOP NOP
Bank,
Col n
Bank,
Col b
CL = 2.5
DQ
DO
n
DO
b
DONT CARE TRANSITIONING DATA
NOTE: 1. DO n (or b) = data-out from column n (or column b).
2. Burst length = 4 or 8 (if 4, the bursts are concatenated; if 8, the second burst interrupts the first).
3. Three subsequent elements of data-out appear in the programmed order following DO n.
4. Three (or seven) subsequent elements of data-out appear in the programmed order following DO b.
5. Shown with nominal
t
AC, tDQSCK, and tDQSQ.
6. Example applies only when READ commands are issued to same device.
Figure 8
Consecutive READ Bursts
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
19
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
CK#
CK
COMMAND
ADDRESS
DQS
DQ
CK#
CK
COMMAND
COMMAND
ADDRESS
ADDRESS
DQS
DQ
T0 T1 T2 T3T2n T3n T4 T5 T5n T6
READ NOP NOP NOP NOP NOP
Bank,
Col n
READ
Bank,
Col b
CL = 2
DO
n
DO
b
T0 T1 T2 T3T2n T3n T4 T5 T5n T6
READ NOP NOP NOP NOP NOP
Bank,
Col n
READ
Bank,
Col b
CL = 2.5
DO
n
DO
b
NOTE: 1. DO n (or b) = data-out from column n (or column b).
DONT CARE TRANSITIONING DATA
2. Burst length = 4 or 8 (if 4, the bursts are concatenated; if 8, the second burst interrupts the first).
3. Three subsequent elements of data-out appear in the programmed order following DO n.
4. Three (or seven) subsequent elements of data-out appear in the programmed order following DO b.
5. Shown with nominal
t
AC, tDQSCK, and tDQSQ.
6. Example applies when READ commands are issued to different devices or nonconsecutive READs.
Figure 9
Nonconsecutive READ Bursts
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
20
ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
CK#
CK
COMMAND
ADDRESS
DQS
DQ
CK#
CK
COMMAND
COMMAND
ADDRESS
ADDRESS
DQS
T0 T1 T2 T3T2n T3n T4 T5T4n T5n
READ READ READ NOP NOP
Bank,
Col n
Bank,
Col x
Bank,
Col b
READ
Bank, Col g
CL = 2
DO
n
DO
n'
DO
x
DO
x'
DO
b
DO
b'
DO
g
T0 T1 T2 T3T2n T3n T4 T5T4n T5n
READ READ READ NOP NOP
Bank,
Col n
Bank,
Col x
Bank,
Col b
READ
Bank, Col g
CL = 2.5
DQ
DO
n
DO
n'
DO
x
DO
x'
DO
b
DO
b'
DONT CARE TRANSITIONING DATA
NOTE: 1. DO n (or x or b or g) = data-out from column n (or column x or column b or column g).
2. Burst length = 2 or 4 or 8 (if 4 or 8, the following burst interrupts the previous).
3. n' or x' or b' or g' indicates the next data-out following DO n or DO x or DO b or DO g, respectively.
4. READs are to an active row in any bank.
5. Shown with nominal
t
AC, tDQSCK, and tDQSQ.
Figure 10
Random READ Accesses
512Mb: x4, x8, x16 DDR SDRAM Micron Technology, Inc., reserves the right to change products or specifications without notice. 512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01 ©2001, Micron Technology, Inc.
21
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