mpc8250 Freescale Semiconductor, Inc, mpc8250 Datasheet - Page 19

• Manufacturer Part Number: mpc8250
• Description: Mpc8250 Powerquicc Ii Integrated Communications Processor
• Manufacturer: Freescale Semiconductor, Inc

Figure 11
Freescale Semiconductor
shows signal behavior in MEMC mode.
Generally, all MPC8250 bus and system output signals are driven from the
rising edge of the input clock (CLKin). Memory controller signals,
however, trigger on four points within a CLKin cycle. Each cycle is divided
by four internal ticks: T1, T2, T3, and T4. T1 always occurs at the rising
edge, and T3 at the falling edge, of CLKin. However, the spacing of T2 and
T4 depends on the PLL clock ratio selected, as shown in
Figure 12
Memory controller signals
1:2, 1:3, 1:4, 1:5, 1:6
CLKin
CLKin
CLKin
PLL Clock Ratio
Figure 12. Internal Tick Spacing for Memory Controller Signals
1:2.5
1:3.5
T1
T1
T1
is a graphical representation of
Table 11. Tick Spacing for Memory Controller Signals
CLKin
V_CLK
T2
MPC8250 Hardware Specifications, Rev. 1
T2
T2
Figure 11. MEMC Mode Diagram
1/4 CLKin
3/10 CLKin
4/14 CLKin
Tick Spacing (T1 Occurs at the Rising Edge of CLKin)
T3
T3
T3
T2
NOTE
T4
T4
T4
1/2 CLKin
1/2 CLKin
1/2 CLKin
Table
sp34/sp30
T3
11.
for 1:2, 1:3, 1:4, 1:5, 1:6
for 1:2.5
for 1:3.5
Table
3/4 CLKin
8/10 CLKin
11/14 CLKin
Electrical and Thermal Characteristics
11.
T4
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