TMS320VC5401 Datasheet, PDF (49/81 Pages) Texas Instruments – Fixed-Point Digital Signal Processor

Electrical Specifications
5.6 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 5−2. The load capacitors, C₁ and C₂, should be chosen such that the equation below is satisfied. C_L
in the equation is the load specified for the crystal.
C_L +
C₁C₂
(C₁ ) C₂)
Table 5−2. Input Clock Frequency Characteristics
f_clock Input clock frequency
MIN MAX UNIT
10 20
MHz
X1
C₁
X2/CLKIN
Crystal
C₂
Figure 5−2. Internal Oscillator With External Crystal
December 2000 − Revised February 2004
SPRS153C
49