mpc8640 Freescale Semiconductor, Inc, mpc8640 Datasheet - Page 21

• Manufacturer Part Number: mpc8640
• Description: Integrated Host Processor
• Manufacturer: Freescale Semiconductor, Inc

6.2
This section provides the AC electrical characteristics for the DDR SDRAM interface.
6.2.1
Table 18
Table 19
At recommended operating conditions (see
Table 20
At recommended operating conditions (see
Freescale Semiconductor
At recommended operating conditions (see
AC input low voltage
AC input high voltage
Controller Skew for
MDQS—MDQ/MECC
533 MHz
Note:
1. t
2. The amount of skew that can be tolerated from MDQS to a corresponding MDQ signal is called t
3. Maximum DDR1 frequency is 400 MHz.
AC input low voltage
AC input high voltage
will be captured with MDQS[n]. This should be subtracted from the total timing budget.
determined by the following equation: t
absolute value of t
CISKEW
provides the input AC timing specifications for the DDR2 SDRAM when Dn_GV
provides the input AC timing specifications for the DDR SDRAM when Dn_GV
provides the input AC timing specifications for the DDR SDRAM interface.
represents the total amount of skew consumed by the controller between MDQS[n] and any corresponding bit that
DDR SDRAM AC Electrical Characteristics
DDR SDRAM Input AC Timing Specifications
Parameter
Parameter
Parameter
400 MHz
MPC8640 and MPC8640D Integrated Host Processor Hardware Specifications, Rev. 3
Table 18. DDR2 SDRAM Input AC Timing Specifications for 1.8-V Interface
Table 19. DDR SDRAM Input AC Timing Specifications for 2.5-V Interface
CISKEW
.
Table 20. DDR SDRAM Input AC Timing Specifications
Table
Table
Table
DISKEW
2)
2)
2)
Symbol
Symbol
Symbol
t
CISKEW
V
V
V
V
—
—
IH
IH
IL
IL
= ±(T ³ 4 – abs(t
D n _MV
D n _MV
CISKEW
–300
–365
Min
Min
Min
REF
REF
—
—
—
+ 0.25
+ 0.31
)) where T is the clock period and abs(t
D n _MV
D n _MV
Max
Max
Max
300
365
REF
REF
—
—
—
– 0.25
– 0.31
DISKEW
DDR and DDR2 SDRAM
.This can be
Unit
Unit
Unit
DD(typ)
ps
—
—
V
V
DD(typ)
V
V
CISKEW
= 2.5 V.
= 1.8 V.
Notes
Notes
Notes
) is the
1, 2
—
—
—
—
—
3
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