8. AC Operating Conditions & Timming Specification
8.1 AC Operating Conditions
8.2 AC Timming Parameters & Specification
24
25
26
27
28
29
30
31
32
33
37
37
37
38
41
41
42
9. AC Operating Test Conditions
10. Input/Output Capacitance
11. IBIS: I/V Characteristics for Input and Output Buffers
11.1 Normal strength driver
44
44
45
45
47
11.2 Half strength driver
12. QFC function
QFC definition
QFC timming on Read Operation
QFC timming on Write operation with tDQSSmax
QFC timming on Write operation with tDQSSmin
QFC timming example for interrupted writes operation
Timing Diagram
- 4 -
REV. 0.3 November 2. 2000
49
49
49
50
50
51
52
256Mb DDR SDRAMPreliminary
List of tables
Table 1 : Operating frequency and DLL jitter
Table 2. : Column address configurtion
Table 3 : Input/Output function description
Table 4 : Burst address ordering for burst length
Table 5 : Bank selection for precharge by bank address bits
Table 6 : Operating description when new command asserted while
read with auto precharge is issued
Table 7 : Operating description when new command asserted while
write with auto precharge is issued
Table 8 : Command truth table
Table 9-1 : Functional truth table
Table 9-2 : Functional truth table (contiued)
Table 9-3 : Functional truth table (contiued)
Table 9-4 : Functional truth table (contiued)
Table 10 : Absolute maximum raings
Table 11 : DC operating condtion
Table 12 : DDR SDRAM spec Items and Test Conditions
Table 13 : DDR SDRAM IDD spec Table
Table 14 : AC operating condition
Table 15 : AC timing parameters and specifications
Table 16 : AC operating test conditions Table 17 : Input/Output capacitance Table 18 : Pull down and pull up current values for normal strength driver Table 19 : Pull down and pull up current values for half strength driver
8
9
10
15
17
28
29
32
33
34
35
36
37
37
38
40
41
43
44
44
46
48
- 5 -
REV. 0.3 November 2. 2000
256Mb DDR SDRAMPreliminary
List of figures
Figure 1 : 256Mb Package Pinout
Figure 2 : Package dimension
Figure 3 :State digram
Figure 4 : Power up and initialization sequence
Figure 5 : Mode register set
Figure 6 : Mode register set sequence
Figure 7 : Extend mode register set
Figure 8 : Bank activation command cycle timing
Figure 9 : Burst read operation timing
Figure 10 : Burst write operation timing
Figure 11 : Read interrupted by a read timing
Figure 12 : Read interrupted by a write and burst stop timing
Figure 13 : Read interrupted by a precharge timing
Figure 14 : Write interrupted by a write timing
Figure 15 : Write interrupted by a read and DM timing Figure 16 : Write interrupted by a precharge and DM timing
Figure 17 : Burst stop timing Figure 18 : DM masking timing Figure 19 : Read with auto precharge timing Figure 20 : Write with auto precharge timing
Figure 21 : Auto refresh timing
Figure 22 : Self refresh timing
Figure 23 : Power down entry and exit timing
Figure 24 : Output Load Circuit (SSTL_2)
Figure 25 : I / V characteristics for input/output buffers:
pull-up(above) and pull-down(below) for normal strength driver
Figure 26 : I / V characteristics for input/output buffers:
pull-up(above) and pull-down(below) for half strength driver
Figure 27 : QFC timing on read operation
Figure 28 : QFC timing on write operation with tDQSSmax
Figure 29 : QFC timing on write operation with tDQSSmin
Figure 30 : QFC timing example for interrupted writes operation
DM is internally loaded to match DQ and DQS identically.
Table 2. Column address configuration
- 9 -
REV. 0.3 November 2. 2000
256Mb DDR SDRAMPreliminary
2.2 Input/Output Function Description
SYMBOLTYPEDESCRIPTION
CK, CKInputClock : CK and CK are differential clock inputs. All address and control input signals are sam-
CKEInputClock Enable : CKE HIGH activates, and CKE LOW deactivates internal clock signals, and
CSInputChip Select : CS enables(registered LOW) and disables(registered HIGH) the command
RAS, CAS, WEInputCommand Inputs : RAS, CAS and WE (along with CS) define the command being entered.
LDM,(U)DMInputInput Data Mask : DM is an input mask signal for write data. Input data is masked when DM is
BA0, BA1InputBank Addres Inputs : BA0 and BA1 define to which bank ACTIVE, READ, WRITE or PRE-
A [n : 0]InputAddress Inputs : Provide the row address for ACTIVE commands, the column address and
DQI/OData Input/Output : Data bus
LDQS,(U)DQSI/OData Strobe : Output with read data, input with write data. Edge-aligned with read data, cen-
QFCOutputFET Control : Optional. Output during every Read and Write access. Can be used to control
NC-No Connect : No internal electrical connection is present.
VDDQSupplyDQ Power Supply : +2.5V ± 0.2V.
VSSQSupplyDQ Ground.
VDDSupplyPower Supply : +2.5V ± 0.2V (device specific).
VSSSupplyGround.
VREFInputSSTL_2 reference voltage.
pled on the positive edge of CK and negative edge of CK. Output (read) data is referenced to
both edges of CK. Internal clock signals are derived from CK/CK.
device input buffers and output drivers. Deactivating the clock provides PRECHARGE
POWER-DOWN and SELF REFRESH operation (all banks idle), or ACTIVE POWER-DOWN
(row ACTIVE in any bank). CKE is synchronous for all functions except for disabling outputs,
which is achieved asynchronously. Input buffers, excluding CK, CK and CKE are disabled
during power-down and self refresh modes, providing low standby power. CKE will recognize
an LVCMOS LOW level prior to VREF being stable on power-up.
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.
sampled HIGH along with that input data during a WRITE access. DM is sampled on both
edges of DQS. DM pins include dummy loading internally, to matches the DQ and DQS loading. For the x16, LDM corresponds to the data on DQ0-DQ7 ; UDM correspons to the data on
DQ8-DQ15.
CHARGE command is being applied.
AUTO PRECHARGE bit for READ/WRITE commands, to select one location out of the memory array in the respective bank. A10 is sampled during a PRECHARGE command to determine whether the PRECHARGE applies to one bank (A10 LOW) or all banks (A10 HIGH). If
only one bank is to be precharged, the bank is selected by BA0, BA1. The address inputs also
provide the op-code during a MODE REGISTER SET command. BA0 and BA1 define which
mode register is loaded during the MODE REGISTER SET command (MRS or EMRS).
tered in write data. Used to capture write data. For the x16, LDQS corresponds to the data on
DQ0-DQ7 ; UDQS corresponds to the data on DQ8-DQ15.
The following sequence is required for POWER UP and Initialization.
1. Apply power and attempt to maintain CKE at a low state(all other inputs may be undefined.)
- Apply VDD before or at the same time as VDDQ.
- Apply VDDQ before or at the same time as VTT & Vref.
2. Start clock and maintain stable condition for a minimum of 200us.
3. The minimum of 200us after stable power and clock(CK, CK), apply NOP & take CKE high.
4. Issue precharge commands for all banks of the device.
*1
5. Issue EMRS to enable DLL.(To issue "DLL Enable" command, provide "Low" to A0, "High" to BA0 and "Low"
to all of the rest address pins, A1~A11 and BA1)
6. Issue a mode register set command for "DLL reset". The additional 200 cycles of clock input is required to
*1
lock the DLL.
(To issue DLL reset command, provide "High" to A8 and "Low" to BA0)
*2
7. Issue precharge commands for all banks of the device.
8. Issue 2 or more auto-refresh commands.
9. Issue a mode register set command with low to A8 to initialize device operation.
*1 Every "DLL enable" command resets DLL. Therefore sequence 6 can be skipped during power up.
Instead of it, the additional 200 cycles of clock input is required to lock the DLL after enabling DLL.
*2 Sequence of 6 & 7 is regardless of the order.
Power up & Initialization Sequence
012345678910111213141516171819
CK
CK
Command
precharge
ALL Banks
tRP
EMRS
2 Clock min.
MRS
DLL Reset
∼
∼
2 Clock min.
precharge
ALL Banks
tRP
1st Auto
Refresh
tRFC
∼
∼
∼
∼
min.200 Cycle
∼
∼
2nd Auto
Refresh
Figure 4. Power up and initialization sequence
- 13 -
REV. 0.3 November 2. 2000
tRFC
∼
∼
∼
∼
∼
∼
∼
∼
Mode
Register Set
2 Clock min.
Any
Command
256Mb DDR SDRAMPreliminary
3.2.2 Mode Register Definition
3.2.2.1 Mode Register Set(MRS)
The mode register stores the data for controlling the various operating modes of DDR SDRAM. It programs
CAS latency, addressing mode, burst length, test mode, DLL reset and various vendor specific options to make
DDR SDRAM useful for variety of different applications. The default value of the mode register is not defined,
therefore the mode register must be written after EMRS setting for proper DDR SDRAM operation. The mode
register is written by asserting low on CS, RAS, CAS, WE and BA0(The DDR SDRAM should be in all bank precharge with CKE already high prior to writing into the mode register). The states of address pins A0 ~ A12 in
the same cycle as CS, RAS, CAS, WE and BA0 going low are written in the mode register. Two clock cycles
are requested to complete the write operation in the mode register. The mode register contents can be
changed using the same command and clock cycle requirements during operation as long as all banks are in
the idle state. The mode register is divided into various fields depending on functionality. The burst length uses
A0 ~ A2, addressing mode uses A3, CAS latency(read latency from column address) uses A4 ~ A6. A7 is used
for test mode. A8 is used for DLL reset. A7 must be set to low for normal MRS operation. Refer to the table for
specific codes for various burst lengths, addressing modes and CAS latencies.
The DLL must be enabled for normal operation. DLL enable is required during power-up initialization, and
upon returing to normal operation after having disabled the DLL for the purpose of debug or evaluation (upon
exiting 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.
Output Drive Strength
The normal drive strength for all outputs is specified to be SSTL_2, Class II. Some vendors might also support
a weak driver strength option, intended for lighter load and/or point-to-point environments. I-V curves for the
normal drive strength and weak drive strength will be included in a future revision of this document.
Mode Register Set
201534867
*1
tRP
Mode
Register Set
*2
2 Clock min.
Any
Command
Command
CK
CK
tCK
Precharge
All Banks
*1 : MRS can be issued only at all bank precharge state.
*2 : Minimum tRP is required to issue MRS command.
Figure 6. Mode Register Set sequence
- 15 -
REV. 0.3 November 2. 2000
256Mb DDR SDRAMPreliminary
3.2.2.2 Extended Mode Register Set(EMRS)
The extended mode register stores the data for enabling or disabling DLL, QFC and selecting output driver
size. The default value of the extended mode register is not defined, therefore the extened mode register must
be written after power up for enabling or disabling DLL. The extended mode register is written by asserting low
on CS, RAS, CAS, WE and high on BA0(The DDR SDRAM should be in all bank precharge with CKE already
high prior to writing into the extended mode register). The state of address pins A0 ~ A11 and BA1 in the
same cycle as CS, RAS, CAS and WE going low are written in the extended mode register. Two clock cycles
are required to complete the write operation in the extended mode register. The mode register contents can
be changed using the same command and clock cycle requirements during operation as long as all banks are
in the idle state. A0 is used for DLL enable or disable. "High" on BA0 is used for EMRS. All the other address
pins except A0 and BA0 must be set to low for proper EMRS operation. Refer to the table for specific codes.
A12
BA1 BA0
1
RFURFU : Must be set "0"
BA0An ~ A0
0(Existing)MRS Cycle
1Extended Funtions(EMRS)
A11A10A9A8A7A6A5A4A3A2A1A0
Output Driver Impedence Control
0 Normal
1 Weak
QFC control
0Disable(Default)
1 Enable
QFC
D.I.C
DLL
Address Bus
Extended Mode Register
A0DLL Enable
0Enable
1Disable
Figure 7. Extend Mode Register set
- 16 -
REV. 0.3 November 2. 2000
Loading...
+ 35 hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.