vssa_osc0
Device
xo_osc0
xi_osc0
C
f1
Crystal
Rd
C
f2
(Optional)
Rd
(Optional)
157
AM5706, AM5708
www.ti.com
SPRS961B –AUGUST 2016–REVISED SEPTEMBER 2017
Submit Documentation Feedback
Product Folder Links: AM5706 AM5708
SpecificationsCopyright © 2016–2017, Texas Instruments Incorporated
Figure 5-8. OSC0 Crystal Implementation
NOTE
The load capacitors, C
f1
and C
f2
in Figure 5-8, should be chosen such that the below
equation is satisfied. C
L
in the equation is the load specified by the crystal manufacturer. All
discrete components used to implement the oscillator circuit should be placed as close as
possible to the associated oscillator xi_osc0, xo_osc0, and vssa_osc0 pins.
Figure 5-9. Load Capacitance Equation
The crystal must be in the fundamental mode of operation and parallel resonant. Table 5-17 summarizes
the required electrical constraints.
Table 5-17. OSC0 Crystal Electrical Characteristics
NAME DESCRIPTION MIN TYP MAX UNIT
f
p
Parallel resonance crystal frequency 19.2, 20, 27 MHz
C
f1
C
f1
load capacitance for crystal parallel resonance with C
f1
= C
f2
12 24 pF
C
f2
C
f2
load capacitance for crystal parallel resonance with C
f1
= C
f2
12 24 pF
ESR(C
f1
,C
f2
)
(1)
Crystal ESR 100 Ω
C
O
Crystal shunt capacitance
ESR = 30 Ω
ESR = 40 Ω
19.2 MHz, 20 MHz, 27 MHz 7 pF
ESR = 50 Ω
19.2 MHz, 20 MHz 7 pF
27 MHz 5 pF
ESR = 60 Ω
19.2 MHz, 20 MHz 7 pF
27 MHz Not Supported -
ESR = 80 Ω
19.2 MHz, 20 MHz 5 pF
27 MHz Not Supported -
ESR = 100 Ω
19.2 MHz, 20 MHz 3 pF
27 MHz Not Supported -
L
M
Crystal motional inductance for f
p
= 20 MHz 10.16 mH
C
M
Crystal motional capacitance 3.42 fF
