DRA722_17 Datasheet, PDF (179/408 Pages) Texas Instruments – Infotainment Applications Processor

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DRA722, DRA724, DRA725, DRA726
SPRS956B – MARCH 2016 – REVISED JANUARY 2017
Device
xi_osc1
xo_osc1
vssa_osc1
Crystal
Rd
(Optional)
C_f1
C_f2
SPRS906_CLK_06
Figure 6-6. Crystal Implementation
NOTE
The load capacitors, C_f1 and C_f2 in Figure 6-6, 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_osc1, xo_osc1, and vssa_osc1 pins.
CL=
C C _{f1 f2}
(C_f1+C_f2)
Figure 6-7. Load Capacitance Equation
The crystal must be in the fundamental mode of operation and parallel resonant. Table 6-5 summarizes
the required electrical constraints.
Table 6-5. OSC1 Crystal Electrical Characteristics
NAME
DESCRIPTION
f_p
C_f1
C_f2
ESR(C_f1,C_f2)
C_O
L_M
C_M
Parallel resonance crystal frequency
C_f1 load capacitance for crystal parallel resonance with C_f1 = C_f2
C_f2 load capacitance for crystal parallel resonance with C_f1 = C_f2
Crystal ESR
ESR = 30 Ω 19.2 MHz ≤ f_p ≤ 32 MHz
ESR = 40 Ω 19.2 MHz ≤ f_p ≤ 32 MHz
19.2 MHz ≤ f_p ≤ 25 MHz
ESR = 50 Ω 25 MHz < f_p ≤ 27 MHz
27 MHz < f_p ≤ 32 MHz
19.2 MHz ≤ f_p ≤ 23 MHz
Crystal shunt capacitance
ESR = 60 Ω 23 MHz < f_p ≤ 25 MHz
25 MHz < f_p ≤ 32 MHz
19.2 MHz ≤ f_p ≤ 23 MHz
ESR = 80 Ω 23 MHz ≤ f_p ≤ 25 MHz
25 MHz < f_p ≤ 32 MHz
ESR = 100 Ω ^{19.2 MHz ≤ fp ≤ 20 MHz}
20 MHz < f_p ≤ 32 MHz
Crystal motional inductance for f_p = 20 MHz
Crystal motional capacitance
MIN
TYP
MAX
Range from 19.2 to 32
12
24
12
24
100
7
5
7
5
Not Supported
7
5
Not Supported
5
3
Not Supported
3
Not Supported
10.16
3.42
UNIT
MHz
pF
pF
Ω
pF
pF
pF
pF
-
pF
pF
-
pF
pF
-
pF
-
mH
fF
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Clock Specifications 179