MSP 34x7G
PRELIMINARY DATA SHEET
4.6.2.4. Crystal Recommendations
Symbol
Parameter
Pin Name
Min.
Typ.
Max.
Unit
General Crystal Recommendations
fP
Crystal Parallel Resonance Fre-
18.432
MHz
quency at 12 pF Load Capacitance
RR
C0
CL
Crystal Series Resistance
8
25
Ω
Crystal Shunt (Parallel) Capacitance
External Load Capacitance1)
6.2
7.0
pF
XTAL_IN,
XTAL_OUT
PSDIP
PMQFP
approx. 1.5
approx. 3.3
pF
pF
Crystal Recommendations for FM / NICAM Applications
fTOL
Accuracy of Adjustment
−30
−30
+30
+30
ppm
ppm
DTEM
Frequency Variation
versus Temperature
C1
Motional (Dynamic) Capacitance
15
fF
18.4305
18.4335
fCL
Required Open Loop Clock
MHz
Frequency (Tamb = 25 °C)
1) External capacitors at each crystal pin to ground are required. They are necessary to tune the open-loop fre-
quency of the internal PLL and to stabilize the frequency in closed-loop operation. Due to different layouts, the
accurate capacitor value should be determined with the customer PCB. The suggested values (1.5...3.3 pF) are
figures based on experience and should serve as “start value”.
To adjust the capacitor value, reset the MSP and transfer only the following I2C-protocol:
<80 10 00 20 00 60>.
Measure the frequency at pin TP_CO. Measurement at XTAL_IN/OUT pins is not possible. Change the capaci-
tor value until the frequency matches 18.432/3 = 6.144 MHz as closely as possible. The higher the capacity, the
lower the resulting clock frequency.
Note: To minimize adjustment tolerances for all MSP-generations, it is strongly recommended to use the so-
called MSP-XTAL-REF ICs (available in all packages) for the capacitor adjustment. Since all MSP-XTAL-REF ICs
do have an AUD_CL_OUT-pin with the 18.432 MHz signal, this pin should be used for the capacitor adjustment
instead of the TP_CO-pin. After the reset, no I2C-protocol should be transmitted. The AUD_CL_OUT-signal is
available at the following pins:
PLCC68
PSDIP64
PSDIP52
PQFP80
PLQFP64
PMQFP442)
pin 18
pin 1
pin 2
pin 74
pin 57
pin 8
2) For the MSP-XTAL-REF IC, the PMQFP44 pin functionality of the D_CTR_I/O1-pin has been changed to
the Audio_Clock_Out signal. If D_CTR_I/O1 is used in the customer application, this pin must be left open for
the adjustment procedure.
44
Micronas
MICRONAS [ MICRONAS ]
