without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to
obtain the latest version of this device specification before relying on any published information and before placing orders for products.
Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can
reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such
applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that:
a.) the risk of injury or damage has been minimized;
b.) the user assume all such risks; and
c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances
Integrated Silicon Solution, Inc.
– www.issi.com –
Rev. A
12/3/2013
1
IS43/46DR16128A
DDR2 SDRAM (128Mx16) LF-BGA Ball-out (Top-View)
(10.5mm x 13.5mm Body, 0.8mm pitch)
1
A
B
C
D
E
2
3
4
5
6
7
8
9
F
G
H
J
K
L
M
N
P
R
A13
Symbol
CK, CK#
CKE
CS#
RAS#,CAS#,WE#
A[13:0]
BA[2:0]
DQ[15:0]
UDQS, UDQS#
LDQS, LDQS#
UDM, LDM
VDD
VSS
VDDQ
VSSQ
VREF
VDDL
VSSDL
ODT
NC
Description
Input clocks
Clock enable
Chip Select
Command control inputs
Address
Bank Address
I/O
Upper Byte Data Strobe
Lower Byte Data Strobe
Input data mask
Supply voltage
Ground
DQ power supply
DQ ground
Reference voltage
DLL power supply
DLL ground
On Die Termination Enable
No connect
Note:
VDDL and VSSDL are power and ground for the DLL.
Integrated Silicon Solution, Inc.
– www.issi.com –
Rev. A
12/3/2013
2
IS43/46DR16128A
Functional Description
Power-up and Initialization
DDR2 SDRAMs must be powered up and initialized in a predefined manner. Operational procedures other than those specified may
result in undefined operation.
Power-up and Initialization Sequence
The following sequence is required for Power-up and Initialization.
1. Either one of the following sequence is required for Power-up:
1
A. While applying power, attempt to maintain CKE below 0.2 x VDDQ and ODT at a LOW state (all other inputs may be
undefined.) The VDD voltage ramp time must be no greater than 200 ms from when VDD ramps from 300 mV to
VDD(Min); and during the VDD voltage ramp, |VDD-VDDQ| ≥ 0.3 V. Once the ramping of the supply voltages is
complete (when VDDQ crosses VDDQ(Min)), the supply voltage specifications provided in the table
Recommended DC
Operating Conditions (SSTL_1.8),
prevail.
VDD, VDDL and VDDQ are driven from a single power converter output, AND
VTT is limited to 0.95V max, AND
VREF tracks VDDQ/2, VREF must be within
±
300mV with respect to VDDQ/2 during supply ramp time.
VDDQ ≥ VREF must be met at all times
1
B. While applying power, attempt to maintain CKE below 0.2 x VDDQ and ODT at a LOW state (all other inputs may be
undefined, voltage levels at I/Os and outputs must be less than VDDQ during voltage ramp time to avoid DRAM latch-
up. During the ramping of the supply voltages, VDD ≥ VDDL ≥ VDDQ must be maintained and is applicable to both AC
and DC levels until the ramping of the supply voltages is complete, which is when VDDQ crosses VDDQ min. Once the
ramping of the supply voltages is complete, the supply voltage specifications provided in the table
Recommended DC
Operating Conditions (SSTL-1.8),
prevail.
Apply VDD/VDDL before or at the same time as VDDQ.
VDD/VDDL voltage ramp time must be no greater 200 ms from when VDD ramps from 300 mV to VDD(Min) .
Apply VDDQ before or at the same time as VTT.
The VDDQ voltage ramp time from when VDD(Min) is achieved on VDD to the VDDQ(Min) is achieved on VDDQ
must be no greater than 500 ms.
2. Start clock and maintain stable condition.
3. For the minimum of 200 µs after stable power (VDD, VDDL, VDDQ, VREF, and VTT values are in the range of the minimum and
maximum values specified in the table
Recommended DC Operating Conditions (SSTL-1.8))
and stable clock (CK, CK#), then apply
NOP or Deselect and assert a logic HIGH to CKE.
4. Wait minimum of 400 ns then issue a precharge all command. During the 400 ns period, a NOP or Deselect command must be
issued to the DRAM.
5. Issue an EMRS command to EMR(2).
6. Issue an EMRS command to EMR(3).
7. Issue EMRS to enable DLL.
8. Issue a Mode Register Set command for DLL reset.
9. Issue a precharge all command.
10. Issue 2 or more auto-refresh commands.
11. Issue a MRS command with LOW to A8 to initialize device operation. (i.e. to program operating parameters without resetting
the DLL.)
12. Wait at least 200 clock cycles after step 8 and then execute OCD Calibration. EMRS Default command (A9=A8=A7=HIGH)
followed by EMRS OCD Calibration Mode Exit command (A9=A8=A7=LOW) must be issued with other operating parameters of
EMR(1).
13. The DDR2 SDRAM is now ready for normal operation.
Note:
1. To guarantee ODT off, VREF must be valid and a LOW level must be applied to the ODT pin.
Integrated Silicon Solution, Inc.
– www.issi.com –
Rev. A
12/3/2013
3
IS43/46DR16128A
Initialization Sequence after Power-Up Diagram
tCH
tCL
CK
tIS
~
~
~
NOP
~
~
~
PRE
ALL
~
~
~
EMRS
~
~
~
MRS
~
~
~
PRE
ALL
~
~
~
REF
~
~
~
~
tRFC
REF
~
~
~
~
tRFC
MRS
~
~
~
~
tMRD
EMRS
~
~
~
~
Follow OCD
Flowchart
EMRS
~
~
tIS
CK#
ODT
~
~
tOIT
Any
Com
Command
~
400ns
~
tRP
~
tMRD
~
tMRD
~
tRP
~
Minimum 200 Cycles
DLL
Enable
DLL
Reset
OCD
Default
OCD Cal.
Mode Exit
Programming the Mode Register and Extended Mode Registers
For application flexibility, burst length, burst type, CAS# latency, DLL reset function, write recovery time (WR) are user defined
variables and must be programmed with a Mode Register Set (MRS) command. Additionally, DLL disable function, driver impedance,
additive CAS latency, ODT (On Die Termination), single-ended strobe, and OCD (off chip driver impedance adjustment) are also user
defined variables and must be programmed with an Extended Mode Register Set (EMRS) command. Contents of the Mode Register
(MR) or Extended Mode Registers EMR[1] and EMR[2] can be altered by re-executing the MRS or EMRS Commands. Even if the user
chooses to modify only a subset of the MR, EMR[1], or EMR[2] variables, all variables within the addressed register must be
redefined when the MRS or EMRS commands are issued.
MRS, EMRS and Reset DLL do not affect memory array contents, which mean re-initialization including those can be executed at any
time after power-up without affecting memory array contents.
DDR2 Mode Register (MR) Setting
The mode register stores the data for controlling the various operating modes of DDR2 SDRAM. It controls CAS# latency, burst
length, burst sequence, DLL reset, tWR and active power down exit time to make DDR2 SDRAM useful for various applications. The
default value of the mode register is not defined, therefore the mode register must be written after power-up for proper operation.
The mode register is written by asserting LOW on CS#, RAS#, CAS#, WE#, BA0, BA1, and BA2 while controlling the state of address
pins A0 - A13. The DDR2 SDRAM should be in all bank precharge with CKE already HIGH prior to writing into the mode register. The
mode register set command cycle time (tMRD) is required to complete the write operation to the mode register. The mode register
contents can be changed using the same command and clock cycle requirements during normal operation as long as all banks are in
the precharge state. The mode register is divided into various fields depending on functionality. Burst length is defined by A0 - A2
with options of 4 and 8 bit burst lengths. The burst length decodes are compatible with DDR SDRAM. Burst address sequence type is
defined by A3; CAS latency is defined by A4 - A6. The DDR2 doesn’t support half clock latency mode. A7 is used for test mode. A8 is
used for DLL reset. A7 must be set to LOW for normal MRS operation. Write recovery time tWR is defined by A9 - A11. Refer to the
table for specific codes.
Integrated Silicon Solution, Inc.
– www.issi.com –
Rev. A
12/3/2013
4
IS43/46DR16128A
Mode Register (MR) Diagram
Address
Field
BA2
BA1
BA0
A13
(1)
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
Burst
Length
BT
CAS
Latency
DLL
TM
WR
Mode
Register
0
0
0
0
PD1
A12
0
1
A11
0
0
0
0
1
1
1
1
A8
0
1
Active power down exit time
Fast exit (use tXARD)
Slow exit(use tXARDS)
A10
0
0
1
1
0
0
1
1
A9
0
1
0
1
0
1
0
1
DLL Reset
No
Yes
WR(cycles)
(2)
Reserved
2
3
4
5
6
7
8
A7
0
1
CAS Latency
Reserved
Reserved
Reserved
3
4
5
6
7
Mode
Normal
Reserved
A6
0
0
0
0
1
1
1
1
A3
0
1
A2
0
0
A5
0
0
1
1
0
0
1
1
A4
0
1
0
1
0
1
0
1
Burst Type
Sequential
Interleave
A1
1
1
A0
0
1
BL
4
8
Notes:
1. A13 is reserved for future use and must be set to 0 when programming the MR.
2. WR(write recovery for autoprecharge) min is determined by tCK max and WR max is determined by tCK min. WR in clock cycles is calculated by dividing tWR (in
ns) by tCK (in ns) and rounding up a non-integer value to the next integer (WR[cycles] = tWR(ns)/tCK(ns)). The mode register must be programmed to this value.
This is also used with tRP to determine tDAL.
DDR2 Extended Mode Register 1 (EMR[1]) Setting
The extended mode register 1 stores the data for enabling or disabling the DLL, output driver strength, ODT value selection and
additive latency. The default value of the extended mode register is not defined, therefore the extended mode register must be
written after power-up for proper operation. Extended mode register 1 is written by asserting LOW on CS#, RAS#, CAS#, WE#, BA1,
and BA2, and HIGH on BA0, and controlling pins A0 – A13. The DDR2 SDRAM should be in all bank precharge with CKE already HIGH
prior to writing into the extended mode register. The mode register set command cycle time (tMRD) must be satisfied to complete
the write operation to the extended mode register. Mode register contents can be changed using the same command and clock
cycle requirements during normal operation as long as all banks are in the precharge state. A0 is used for DLL enable or disable. A1 is
used for enabling reduced strength data-output driver. A3 - A5 determines the additive latency, A2 and A6 are used for ODT value
selection, A7 - A9 are used for OCD control, A10 is used for DQS# disable and A11 is used for RDQS enable.
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
