Texas Instruments TMS320VC5402 - Manual (Page 36)

TMS320VC5402
FIXEDĆPOINT DIGITAL SIGNAL PROCESSOR
SPRS079E – OCTOBER 1998 – REVISED AUGUST 2000
36 POST OFFICE BOX 1443
•
HOUSTON, TEXAS 77251–1443
internal oscillator with external crystal
The internal oscillator is enabled by connecting a crystal across X1 and X2/CLKIN. The frequency of CLKOUT
is a multiple of the oscillator frequency. The multiply ratio is determined by the bit settings in the CLKMD register.
The crystal should be in fundamental-mode operation, and parallel resonant, with an effective series resistance
of 30
Ω
and power dissipation of 1 mW.
The connection of the required circuit, consisting of the crystal and two load capacitors, is shown in Figure 10.
The load capacitors, C
1
and C
2
, should be chosen such that the equation below is satisfied. C
L
in the equation
is the load specified for the crystal.
C
L
+
C
1
C
2
( C
1
) C
2
)
recommended operating conditions of internal oscillator with external crystal (see Figure 10)
MIN MAX UNIT
fclock Input clock frequency 10 20 MHz
X1 X2/CLKIN
C1 C2
Crystal
Figure 10. Internal Oscillator With External Crystal