ACS8527 데이터 시트보기 (PDF) - Semtech Corporation
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ACS8527 Datasheet PDF : 22 Pages
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ACS8527 MUXPLL
ADVANCED COMMUNICATIONS
FINAL
Table 6 Output 02 Frequency Selection by Hardware Configuration
O2_FREQ
SONSDHB Pin O1_FREQ =
2
1
0
‘‘001’’
0
0
0
X
X
0
0
0
1
FALSE
1
0
0
0
1
TRUE
1
0
X
0
1
0
1
X
0
1
1
X
X
1
0
0
X
X
1
0
1
X
X
1
1
0
X
X
1
1
1
X
X
DATASHEET
Output Frequency/
MHz
0
2.048
1.544
2.048
3.088
34.368
44.736
19.44
25.92
38.88
51.84
77.76
Jitter Level (typ)
rms (ps) p-p (ns)
-
-
400
2
200
1.2
900
0.45
110
0.75
120
1
110
1
60
0.6
60
0.6
60
0.6
60
0.6
60
0.6
Local Oscillator Clock
The Master system clock on the ACS8527 should be
provided by an external clock oscillator of frequency
12.800 MHz. Wander on the local oscillator clock will not
have a significant effect on the output clock whilst in
Locked mode. Prior to initial lock or in Digital Holdover
mode, wander on the crystal is more significant. Variation
in crystal temperature or supply voltage both cause drifts
in operating frequency, as does ageing. These effects
must be limited by careful selection of a suitable
component for the local oscillator.
Please contact Semtech for information on crystal
oscillator suppliers.
Power-On Reset
The Power-On Reset (PORB) pin resets the device if forced
Low. The reset is asynchronous, the minimum Low pulse
width is 5 ns. Reset must be asserted at power on, and
may be re-asserted at any time to restore defaults. This is
implemented simply using an external capacitor to GND
along with the internal pull-up resistor. The ACS8527
holds itself in a reset state for 250 ms after the PORB pin
has been pulled High. In normal operation PORB should
be held High.
Status Reporting
In the event of loss of SEC input signal, LOS flag is raised
on the LOS_ALARM pin. The LOS alarm is active low, and
high impedance when inactive, i.e. when an LOS alarm
exists, the output will be driven low; with no LOS alarm,
the output will float. This is designed to be able to be
connected to a processor together with other interrupt
sources to trigger an interrupt. The output will require a
pull-up resistor to pull the voltage up when the alarm is
inactive.
Revision 4.01/June 2006 © Semtech Corp.
Page 9
www.semtech.com
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