S42
Hardware User Guide
1VV0301303 Rev. 11
Page 28 of 85
2021-05-06
Not Subject to NDA
Warning: Please note that the Telit EVK Board for the S42
has an XTAL circuitry populated.
In case an evaluation without XTAL is intended please refer to EVK
Documentation how to disable the XTAL.
3.9.1.
32,768 kHz Crystal Oscillator Specification (32k XOSC)
Symbol
Item
Condition
Limit
Unit
Min
Typ
Max
fNOM
Crystal Frequency
Tamb = 25°C
32,768
kHz
fTOL
Frequency Tolerance for
BLE applications
including temperature
and aging (1)
+/-250
ppm
CL
Load Capacitance
12,5
pF
C0
Shunt Capacitance
2
pF
RS
Equivalent Series
Resistance
100
k
Ω
PD
Drive Level
1
µW
Cpin
Input Cap. On XL-IN and
XL-OUT
4
pF
(1) adjust crystal frequency by choosing correct value for C1, C2 (value depends on CL of crystal and
layout)
Table 6: 32,768kHz Crystal Oscillator
The module’
s firmware will detect the presence of a slow clock during the boot process
and switch behavior appropriately.
3.9.2.
Connection of an External 32,768 kHz Crystal
Connect the 32,768 kHz crystal and two capacitors C1, C2 at pins A-6 (XL-IN) and A-5 (XL-
OUT). The crystal must comply with specifications given in Table 6. The exact value of C1
and C2 depends on the crystal and the stray capacitance of the layout. Select C1, C2 such
that the slow clock oscillator operates at the exact frequency at room temperature (25°C).
C1 and C2 shall be of equal capacity. The crystal and the capacitors shall be located as
close as possible to pins A-5, A-6.
