RESET Initialization
5 RESET Initialization
This section describes the AC electrical specifications for the RESET initialization timing requirements of
the MPC8548E. Table 8 provides the RESET initialization AC timing specifications for the DDR SDRAM
component(s).
Table 8. RESET Initialization Timing Specifications
Parameter/Condition
Required assertion time of HRESET
Min
Max
Unit
Notes
100
3
—
—
—
—
μs
—
1
Minimum assertion time for SRESET
SYSCLKs
μs
PLL input setup time with stable SYSCLK before HRESET negation
100
4
—
1
Input setup time for POR configs (other than PLL config) with respect to
negation of HRESET
SYSCLKs
Input hold time for all POR configs (including PLL config) with respect to
negation of HRESET
2
—
5
SYSCLKs
SYSCLKs
1
1
Maximum valid-to-high impedance time for actively driven POR configs with
respect to negation of HRESET
—
Note:
1. SYSCLK is the primary clock input for the MPC8548E.
Table 9 provides the PLL lock times.
Table 9. PLL Lock Times
Parameter/Condition
Min
Max
Unit
Core and platform PLL lock times
Local bus PLL lock time
—
—
—
100
50
μs
μs
μs
PCI/PCI-X bus PLL lock time
50
5.1
Power-On Ramp Rate
This section describes the AC electrical specifications for the power-on ramp rate requirements.
Controlling the maximum power-on ramp rate is required to avoid falsely triggering the ESD circuitry.
Table 10 provides the power supply ramp rate specifications.
Table 10. Power Supply Ramp Rate
Parameter
Required ramp rate for MVREF
Min
Max
Unit
Notes
—
—
3500
4000
V/s
V/s
1
Required ramp rate for VDD
1, 2
Note:
1. Maximum ramp rate from 200 to 500 mV is most critical as this range may falsely trigger the ESD circuitry.
2. VDD itself is not vulnerable to false ESD triggering; however, as per Section 21.2, “PLL Power Supply Filtering,” the
recommended AVDD_CORE, AVDD_PLAT, AVDD_LBIU, AVDD_PCI1 and AVDD_PCI2 filters are all connected to VDD.
Their ramp rates should be equal to or less than the VDD ramp rate.
MPC8548E PowerQUICC™ III Integrated Processor Hardware Specifications, Rev. 6
18
Freescale Semiconductor
FREESCALE [ Freescale ]
