MPC755 RISC Microprocessor Hardware Specifications, Rev. 8
12
Freescale Semiconductor
Electrical and Thermal Characteristics
4.2
AC Electrical Characteristics
This section provides the AC electrical characteristics for the MPC755. After fabrication, functional parts
and tested for conformance to the AC specifications for that frequency. The processor core frequency is
determined by the bus (SYSCLK) frequency and the settings of the PLL_CFG[0:3] signals. Parts are sold
4.2.1
Clock AC Specifications
Table 8 provides the clock AC timing specifications as defined in
Figure 3.
Table 8. Clock AC Timing Specifications
At recommended operating conditions (see
Table 3)Characteristic
Symbol
Maximum Processor Core Frequency
Unit
Notes
300 MHz
350 MHz
400 MHz
Min
Max
Min
Max
Min
Max
Processor frequency
fcore
200
300
200
350
200
400
MHz
1
VCO frequency
fVCO
400
600
400
700
400
800
MHz
1
SYSCLK frequency
fSYSCLK
25
100
25
100
25
100
MHz
1
SYSCLK cycle time
tSYSCLK
10
40
10
40
10
40
ns
SYSCLK rise and fall time
tKR, tKF
—2.0
ns
2
tKR, tKF
—1.4
ns
2
SYSCLK duty cycle measured at
OVDD/2
tKHKL/
tSYSCLK
40
60
40
60
40
60
%
3
SYSCLK jitter
—
±150
—
±150
—
±150
ps
3, 4
Internal PLL relock time
—100
μs3, 5
Notes:
1. Caution: The SYSCLK frequency and PLL_CFG[0:3] settings must be chosen such that the resulting SYSCLK (bus)
frequency, CPU (core) frequency, and PLL (VCO) frequency do not exceed their respective maximum or minimum operating
,” for valid PLL_CFG[0:3]
settings.
2. Rise and fall times measurements are now specified in terms of slew rates, rather than time to account for selectable I/O bus
interface levels. The minimum slew rate of 1 V/ns is equivalent to a 2 ns maximum rise/fall time measured at 0.4 and 2.4 V
(OVDD = 3.3 V) or a rise/fall time of 1 ns measured at 0.4 and 1.8 V (OVDD = 2.5 V).
3. Timing is guaranteed by design and characterization.
4. This represents total input jitter—short term and long term combined—and is guaranteed by design.
5. Relock timing is guaranteed by design and characterization. PLL-relock time is the maximum amount of time required for PLL
lock after a stable VDD and SYSCLK are reached during the power-on reset sequence. This specification also applies when
the PLL has been disabled and subsequently re-enabled during sleep mode. Also note that HRESET must be held asserted
for a minimum of 255 bus clocks after the PLL-relock time during the power-on reset sequence.