mpc7450 Freescale Semiconductor, Inc, mpc7450 Datasheet - Page 24

• Manufacturer Part Number: mpc7450
• Description: Mpc7450 Risc Microprocessor
• Manufacturer: Freescale Semiconductor, Inc

Electrical and Thermal Characteristics
Figure 10 shows the L3 bus timing diagrams for the MPC7450 interfaced to MSUG2 SRAMs.
1.5.2.4.2
When using PB2 or Late Write SRAMs at the L3 interface, the parts should be connected as shown in
Figure 11. These SRAMs are synchronous to the MPC7450; one L3_CLKn signal is output to each SRAM
to latch address, control, and write data. Read data is launched by the SRAM synchronous to the delayed
L3_CLKn signal it received. The MPC7450 needs a copy of that delayed clock which launched the SRAM
read data to know when the returning data will be valid. Therefore, L3_ECHO_CLK1 and
L3_ECHO_CLK3 must be routed halfway to the SRAMs and then returned to the MPC7450 inputs
L3_ECHO_CLK0 and L3_ECHO_CLK2 respectively. Thus, L3_ECHO_CLK0 and L3_ECHO_CLK2 are
phase-aligned with the input clock received at the SRAMs. The MPC7450 will latch the incoming data on
the rising edge of L3_ECHO_CLK0 and L3_ECHO_CLK2.
Table 13 provides the L3 bus interface AC timing specifications for the configuration shown in Figure 11,
assuming the timing relationships of Figure 12 and the loading of Figure 8.
24
L3_ECHO_CLK[0,1,2,3]
Outputs
Note: t
Inputs
Note: t
ADDR, L3CNTL
L3DATA WRITE
L3 Data and Data
L3_CLK[0,1]
time before the clock edge.
time after the clock edge.
L3CHDV
L3DVEH
Parity Inputs
L3 Bus AC Specifications for PB2 and Late Write SRAMs
and t
and t
Figure 10. L3 Bus Timing Diagrams for L3 Cache DDR SRAMs
L3DVEL
L3CLDV
MPC7450 RISC Microprocessor Hardware Specifications
as drawn here will be negative numbers, i.e., input setup time will be
as drawn here will be negative numbers, i.e., output valid time will be
Freescale Semiconductor, Inc.
For More Information On This Product,
VM
t
L3CHOV
VM = Midpoint Voltage (GV
Go to: www.freescale.com
t
L3CHDV
t
L3CHDX
VM
t
t
L3DXEH
L3DVEH
VM
t
L3CHOX
VM
t
L3CHOZ
t
L3DVEL
DD
/2)
VM
VM
t
L3CLDV
t
L3CLDX
t
VM
L3CLDZ
VM
t
L3DXEL
VM
MOTOROLA
VM