XE8000EV101 Semtech, XE8000EV101 Datasheet - Page 46

• Manufacturer Part Number: XE8000EV101
• Description: EVAL BOARD FOR XE8801AMI027LF
• Manufacturer: Semtech
• Type: MCUr

Specifications of XE8000EV101

• Contents: Fully Assembled Evaluation Board
• For Use With/related Products: XE88LC01AMI027
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

The tolerances on the minimal frequency and the drift with supply or temperature can be cancelled using the
software DFLL (digital frequency locked loop) which uses the crystal oscillator as a reference frequency.
7.5.2
7.5.2.1
The Xtal operates with an external crystal of 32’768 Hz.
During Xtal oscillator start-up, the first 32768 cycles are masked. The two bits EnableXtal and ColdXtal in register
RegSysClock control the oscillator.
At power-on reset or during sleep mode, EnableXtal is reset and ColdXtal is set (Xtal oscillator is not selected at
start-up). The user can start Xtal oscillator by setting EnableXtal. When the Xtal oscillator starts, bit ColdXtal is
reset after 32768 cycles. Before ColdXtal is reset by the system, the Xtal frequency precision is not guaranteed.
The Xtal oscillator can be stopped by the user by resetting bit EnableXtal.
When the user enters into sleep mode, the Xtal is stopped.
When an external clock is detected (ExtClk = 1) or the EnExtClock is set 1, the EnableXtal bit can not be set to 1.
7.5.2.2
The crystal oscillator has been designed for a crystal with the specifications given in Table 7-8. The oscillator
precision can only be guaranteed for this crystal.
For safe operation, low power consumption and to meet the specified precision, careful board layout is required:
© Semtech 2005
Keep lines OSCIN and OSCOUT short and insert a VSS line in between them.
Connect the crystal package to VSS.
No noisy or digital lines near OSCIN or OSCOUT.
Insert guards where needed.
Respect the board specifications of Table 7-9.
Symbol
Fs
CL
Rm
Cm
C0
Rmp
Q
Xtal oscillator
Xtal configuration
Xtal oscillator specifications
Description
Resonance frequency
CL
frequency
Motional resistance
Motional capacitance
Shunt capacitance
Motional resistance of
6
Quality factor
th
overtone (parasitic)
for
nominal
Table 7-8. Crystal specifications.
Min
30k
1.8
0.7
4
7-6
32768
Typ
50k
8.2
2.5
1.1
40
8
400k
Max
100
3.2
2.0
15
Unit
Hz
pF
kΩ
fF
pF
kΩ
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XE8801A – SX8801R
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