RELEASED
PM73123 AAL1GATOR-8
DATASHEET
PMC-2000097
ISSUE 2
8 LINK CES/DBCES AAL1 SAR
monitored to generate 1 of 16 frequencies. In high resolution mode all 8 bits are
monitored to generate 1 of 256 frequencies. SRTS requires the use of normal
mode, while high resolution mode is recommended for Adaptive clock recovery.
9.3.3.8.1 T1 Mode
In T1 mode the 1.544 MHz nominal frequency is synthesized by maintaining a
certain ratio of long cycles to short cycles. The long cycle is comprised of 26
SYS_CLK periods (38.88 MHz). The short cycle is comprised of 25 SYS_CLK
periods. For the nominal frequency in high resolution mode, the synthesis period
is comprised of 3088 cycles. 560 of the 3088 cycles are long cycles and the
remaining 2528 are short cycles. For the nominal frequency in low resolution
mode, the synthesis period is comprised of 193 cycles, 35 of those 193 cycles
are long cycles and the remaining 158 are short cycles. In order to alter the
frequency the number of short cycles is increased or decreased according to the
frequency select value. The resultant frequency is calculated using the following
equation:
38.88 * (M + N)
26M + 25N
M = # long cycles
N = # short cycles
Table 8 shows results of this calculation for various values of frequency select. .
The average increment in frequency is ~3.6 Hz.
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL
148
PMC [ PMC-SIERRA, INC ]
