ACS8520 View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'ACS8520' PDF : 150 Pages View PDF
ACS8520 SETS
ADVANCED COMMUNICATIONS
Address (hex): 4C
Register Name sts_freq_measurement
FINAL
Description
(R/W) Register from which the
frequency measurement result
can be read.
DATASHEET
Default Value 0000 0000
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
freq_measurement_value
Bit 2
Bit 1
Bit 0
Bit No.
Description
Bit Value Value Description
[7:0]
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.
-
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.
Address (hex): 4D
Register Name cnfg_DPLL_soft_limit
Description
(R/W) Register to program the Default Value
soft frequency limit of the two
DPLLs. Exceeding this limit will
have no effect beyond triggering a
flag.
1000 1110
Bit 7
freq_lim_ph_
loss
Bit 6
Bit 5
Bit 4
Bit 3
DPLL_soft_limit_value
Bit 2
Bit 1
Bit 0
Bit No.
Description
Bit Value Value Description
7
[6:0]
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.
0
Phase lost/locked determined normally.
1
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.
Revision 3.02/October 2005 © Semtech Corp.
Page 100
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