XPC7445 Datasheet, PDF (5/12 Pages) Freescale Semiconductor, Inc – RISC Microprocessor Hardware Specifications

Freescale Semiconductor, Inc.
General Parameters
Table 12. L3 Bus Interface AC Timing Specifications for MSUG2 (continued)
At recommended operating conditions. See Table 4.
Parameter
All Speed Grades
Symbol L2CR[12] = 0 and L3CR[12] = 0⁸ L2CR[12] = 1 and L3CR[12] = 1⁸ Unit Notes
Min
Max
Min
Max
L3_CLK to high
t_L3CHOZ
—
t_{L3_CLK}/4 + 2.0
—
t_{L3_CLK}/4 + 2.0 ns
impedance:
All other outputs
Notes:
1. Rise and fall times for the L3_CLK output are measured from 20% to 80% of GV_DD.
2. For DDR, all input specifications are measured from the midpoint of the signal in question to the midpoint voltage
of the rising or falling edge of the input L3_ECHO_CLKn (see Figure 10 in the MPC7455 RISC Microprocessor
Hardware Specifications). Input timings are measured at the pins.
3. For DDR, the input data will typically follow the edge of L3_ECHO_CLKn as shown in Figure 10 in the MPC7455
RISC Microprocessor Hardware Specifications. For consistency with other input setup time specifications, this will
be treated as negative input setup time.
4. t_{L3_ECHO_CLK}/4 is one-fourth the period of L3_ECHO_CLKn. This parameter indicates that the MPC7455 can latch
an input signal that is valid for only a short time before and a short time after the midpoint between the rising and
falling (or falling and rising) edges of L3_ECHO_CLKn at any frequency.
5. All output specifications are measured from the midpoint voltage of the rising (or for DDR write data, also the falling)
edge of L3_CLK to the midpoint of the signal in question. The output timings are measured at the pins. All output
timings assume a purely resistive 50-Ω load (see Figure 8 in the MPC7455 RISC Microprocessor Hardware
Specifications).
6. For DDR, the output data will typically lead the edge of L3_CLKn as shown in Figure 10 in the MPC7455 RISC
Microprocessor Hardware Specifications. For consistency with other output valid time specifications, this will be
treated as negative output valid time.
7. t_{L3_CLK}/4 is one-fourth the period of L3_CLKn. This parameter indicates that the specified output signal is actually
launched by an internal clock delayed in phase by 90°. Therefore, there is a frequency component to the output valid
and output hold times such that the specified output signal will be valid for approximately one L3_CLK period
starting three-fourths of a clock prior to the edge on which the SRAM will sample it and ending one-fourth of a clock
period after the edge it will be sampled.
8. These configuration bits allow the AC timing of the L3 interface to be altered via software. They must be both set or
both cleared; other configurations will increase t_L3CSKW1, which may cause unreliable L3 operation.
MOTOROLA MPC7455 Part Number Specification for the XPC74x5RXnnnNx Series
5
For More Information On This Product,
Go to: www.freescale.com