ACS8520T Semtech, ACS8520T Datasheet - Page 100

• Manufacturer Part Number: ACS8520T
• Description: Synchronous Equipment Timing Source (SETS) for Stratum 3/4E/4 and SMC Systems
• Manufacturer: Semtech

Address (hex):
Address (hex):
Revision 3.02/October 2005 © Semtech Corp.
ADVANCED COMMUNICATIONS
Register Name
Register Name
freq_lim_ph_
loss
Bit No.
Bit No.
Bit 7
[7:0]
Bit 7
[6:0]
7
4C
4D
sts_freq_measurement
Description
freq_measurement_value
This represents the value of the frequency
measurement on the channel number selected in
Reg. 4B (cnfg_registers_source_select). This value
will represent the offset in frequency from the clock
to the frequency monitors. This can be either the
crystal oscillator to the device, or the output of the
T0 DPLL as selected in Bit 7 (freq_mon_clk) of
Reg. 48 cnfg_monitors.
cnfg_DPLL_soft_limit
Description
freq_lim_ph_loss
Bit to enable the phase lost indication when the
DPLL hits its hard frequency limit as programmed in
Reg. 41 and Reg. 42 (cnfg_DPLL_freq_limit). This
results in the DPLL entering the phase lost state any
time the DPLL tracks to the extent of its hard limit.
DPLL_soft_limit_value
Register to program to what extent either of the
DPLLs tracks a source before raising its soft
frequency alarm flag (Bits 5 and 4 of Reg. 09,
sts_operating). This offset is compared to the
crystal oscillator frequency taking into account any
programmed calibration.
Bit 6
Bit 6
Bit 5
Bit 5
Description
Description
freq_measurement_value
Bit 4
Bit 4
FINAL
Page 100
DPLL_soft_limit_value
(R/W) Register from which the
frequency measurement result
can be read.
(R/W) Register to program the
soft frequency limit of the two
DPLLs. Exceeding this limit will
have no effect beyond triggering a
flag.
Bit Value
Bit Value
Bit 3
Bit 3
0
1
-
-
Value Description
This is an 8-bit 2’s complement signed integer. To
calculate the offset in ppm of the selected input
channel, this value should be multiplied by
3.81 ppm.
Value Description
Phase lost/locked determined normally.
Phase lost forced when DPLL tracks to hard limit.
To calculate the ppm offset multiply this 7-bit value
by 0.628 ppm. The limit is symmetrical about zero.
A value of 0001110 bin is equivalent to ±8.79 ppm.
Bit 2
Bit 2
Default Value
Default Value
ACS8520 SETS
Bit 1
Bit 1
DATASHEET
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0000 0000
1000 1110
Bit 0
Bit 0