OMAP5912ZZG Datasheet, PDF (204/269 Pages) Texas Instruments – This data sheet revision history highlights the technical changes made to SPRS231D to generate SPRS231E

Electrical Specifications
5.5.2 Base Oscillator (12, 13, or 19.2 MHz) and Input Clock
The internal base system oscillator is enabled following a device reset. The oscillator requires an external
crystal to be connected across the OSC1_IN and OSC1_OUT pins. If the internal oscillator is not used
(configured in software), an external clock source (12,13, 19.2 MHz) must be applied to the OSC1_IN pin, and
the OSC1_OUT pin must be left unconnected. Because the internal oscillator can be used as a clock source
to the OMAP DPLL, the 12-,13-, or 19.2-MHz crystal oscillation frequency can be multiplied to generate the
DSP clock, MPU clock, traffic controller clock.
The crystal must be in fundamental-mode operation, and parallel resonant, with a maximum effective series
resistance of 50 Ω and a power dissipation of 0.5 mW. The connection of the required circuit, consisting of
the crystal and two load capacitors, is shown in Figure 5−5. The load capacitors, C₁ and C₂, must be chosen
such that the equation below is satisfied (recommended values are C₁ = C₂ = 2C_L). C_L in the equation is the
load specified for the crystal. All discrete components used to implement the oscillator circuit must be placed
as close as possible to the associated oscillator pins (OSC1_IN and OSC1_OUT) and to the V_SS pins closest
to the oscillator pins (ZZG balls AA1 and Y3; ZDY/GDY balls G11 and N5).
NOTE: The base oscillator is powered by the embedded LDO. If an external clock source is used instead of
using the on-chip oscillator, care must be taken that the voltage level driven onto the OSC1_IN pin is no greater
than the LDO voltage level.
C₁ = C₂ = 2C_L (C_L = Crystal Load Capacitance)
OSC1_IN
OSC1_OUT
12, 13, or
19.2-MHz Crystal
C1
C2
Figure 5−5. Internal System Oscillator External Crystal
If USB host function is used, it is recommended that a very low PPM crystal (≤ 50 ppm) be used for the
12,13, or 19.2 MHz oscillator circuit. If the USB host function is not used, then a crystal of ≤ 180 ppm is
recommended. When selecting a crystal, the system design must take into account the temperature and aging
characteristics of a crystal versus the user environment and expected lifetime of the system.
Table 5−3 shows the switching characteristics of the base oscillator.
Table 5−3. Base Oscillator Switching Characteristics
PARAMETER
TEST CONDITIONS
MIN
Start-up time (from power up until oscillating at stable
frequency of 12,13, or 19.2 MHz)
C1 = C2 = 10 pF, CV_DD = 1.3V
I_DDA, active current consumption
C1 = C2 = 10 pF, CV_DD = 1.5V
Oscillation frequency
TYP MAX UNIT
1.7
3 ms
220
12 to
19.2
µA
MHz
204 SPRS231E
December 2003 − Revised December 2005