mpc755ed Freescale Semiconductor, Inc, mpc755ed Datasheet - Page 18

• Manufacturer Part Number: mpc755ed
• Description: Risc Microprocessor Hardware Specifications
• Manufacturer: Freescale Semiconductor, Inc

Electrical and Thermal Characteristics
18
At recommended operating conditions (see
L2CLK frequency
L2CLK cycle time
L2CLK duty cycle
Internal DLL-relock time
DLL capture window
L2CLK_OUT output-to-output skew
L2CLK_OUT output jitter
Notes:
1. L2CLK outputs are L2CLK_OUTA, L2CLK_OUTB, L2CLK_OUT, and L2SYNC_OUT pins. The L2CLK frequency-to-core
2. The nominal duty cycle of the L2CLK is 50% measured at midpoint voltage.
3. The DLL-relock time is specified in terms of L2CLK periods. The number in the table must be multiplied by the period of
4. The L2CR[L2SL] bit should be set for L2CLK frequencies less than 110 MHz. This adds more delay to each tap of the DLL.
5. Allowable skew between L2SYNC_OUT and L2SYNC_IN.
6. This output jitter number represents the maximum delay of one tap forward or one tap back from the current DLL tap as the
7. Guaranteed by design.
frequency settings must be chosen such that the resulting L2CLK frequency and core frequency do not exceed their
respective maximum or minimum operating frequencies. The maximum L2LCK frequency will be system dependent.
L2CLK_OUTA and L2CLK_OUTB must have equal loading.
L2CLK to compute the actual time duration in ns. Relock timing is guaranteed by design and characterization.
phase comparator seeks to minimize the phase difference between L2SYNC_IN and the internal L2CLK. This number must
be comprehended in the L2 timing analysis. The input jitter on SYSCLK affects L2CLK_OUT and the L2 address/data/control
signals equally and, therefore, is already comprehended in the AC timing and does not have to be considered in the L2 timing
analysis.
Parameter
MPC755 RISC Microprocessor Hardware Specifications, Rev. 8
Table 11. L2CLK Output AC Timing Specification
Table
3)
t
CHCL
Symbol
t
L2CSKW
f
t
L2CLK
L2CLK
/t
L2CLK
All Speed Grades
Min
640
2.5
80
45
—
—
0
±150
Max
12.5
450
55
10
50
—
Freescale Semiconductor
L2CLK
MHz
Unit
ns
ns
ps
ps
%
Notes
1, 4
2, 7
3, 7
5, 7
6, 7
6, 7