mpc8378 Freescale Semiconductor, Inc, mpc8378 Datasheet - Page 51

• Manufacturer Part Number: mpc8378
• Description: Powerquicc Ii Pro Processor
• Manufacturer: Freescale Semiconductor, Inc

11.3.1.2
The following equations show how to calculate the allowed skew range between the SD_CLK and
SD_DAT/CMD signals on the PCB.
This means that clock can be delayed versus data up to 8 ns (external delay line) in ideal case of
t
11.3.2
Figure 31
For the input path, the device eSDHC expects to sample the data 1.5 internal clock cycles after it was
driven by the SD card. Since in this mode the SD card drives the data at the rising edge of the clock, a
sufficient delay to the clock and the data must exist to ensure it will not be sampled at the wrong internal
clock falling edge. Note that the internal clock which is guaranteed to be 50% duty cycle is used to sample
the data, and therefore used in the equations.
Freescale Semiconductor
SHSCLKL
t
t
MPC8377E Pins
CLK_DELAY
CLK_DELAY
Output from the
MPC8377E Pin
SD CLK at the
SD Card Pins
= 10 ns:
provides the data and command input timing diagram.
the Card Pin
High-Speed Input Path (Read)
Input at the
SD CLK at
High-Speed Write Meeting Hold (Minimum Delay)
MPC8377E PowerQUICC II Pro Processor Hardware Specifications, Rev. 3
–
–
t
t
DATA_DELAY
DATA_DELAY
t
t
CLK_DELAY
CLK_DELAY
Driving
Edge
t
1/2 Cycle
ODLY
t
OH
t
< t
–
SHSCK
< 10 + 0
< 8
Figure 31. High Speed Input Path
t
DATA_DELAY
SHSCKL
t
CLK_DELAY
(Clock Cycle)
+ t
–
Wrong Edge
2
(MPC8377E Input Setup)
SHSKHOX
< t
SHSCKL
t
DATA_DELAY
+ t
+ t
DATA_DELAY
t
SHSKHOX
SHSIVKH
Enhanced Secure Digital Host Controller (eSDHC)
–
–
t
t
IH
IH
Right Edge
Sampling
Edge
(MPC8377E Input Hold)
t
SHSIXKH
Eqn. 13
Eqn. 14
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