Texas Instruments DM6467 Digital Video Evaluation Module TMDXEVM6467T TMDXEVM6467T Datenbogen
Produktcode
TMDXEVM6467T
(
)
C C
1
2
CL
C
C
1
2
=
+
DEV_MXI/
DEV_CLKIN
DEV_MXO
C1
C2
Crystal
DEV_V
SS
33.3 MHz
1.8 V
DEV_DV
DD18
1.3 V
DEV_CV
DD
DEV_DV
SS
SPRS605C – JULY 2009 – REVISED JUNE 2012
7.4
External Clock Input From DEV_MXI/DEV_CLKIN and AUX_MXI/AUX_CLKIN Pins
The DM6467T device includes two options to provide an external clock input for both the system and
auxiliary oscillators:
auxiliary oscillators:
•
Use an on-chip oscillator with external crystal (fundamental parallel resonant mode only, no overtone
support).
support).
•
Use an external 1.8-V LVCMOS-compatible clock input.
Any input crystal frequency between 27 MHz and 35 MHz can be used for the System Oscillator
(DEV_MXI/DEV_CLKIN).
(DEV_MXI/DEV_CLKIN).
The optimal external clock input frequency for the crystals are 33 MHz or 33.3 MHz for the system
oscillator (DEV_MXI/DEV_CLKIN) and 24 MHz for the auxiliary oscillator.
oscillator (DEV_MXI/DEV_CLKIN) and 24 MHz for the auxiliary oscillator.
provides more
details on Option 1, using an on-chip oscillator with external crystal for the 33.3-MHz system oscillator.
provides more details on Option 1, using an on-chip oscillator with external crystal for the
24-MHz auxiliary oscillator.
provides details on Option 2, using an external 1.8-V
LVCMOS-compatible clock input for the 33.3-MHz system oscillator.
provides details on
Option 2, using an external 1.8-V LVCMOS-compatible clock input for the 24-MHz auxiliary oscillator.
7.4.1
Clock Input Option 1—Crystal
7.4.1.1
33.3-MHz for System Oscillator Clock Input Option 1—Crystal
In this option, a crystal is used as the external clock input to the DM6467T system oscillator.
The 33.3-MHz oscillator provides the reference clock for all DM6467T subsystems and peripherals. The
on-chip oscillator requires an external 33.3-MHz crystal connected across the DEV_MXI and DEV_MXO
pins, along with two load capacitors, as shown in
on-chip oscillator requires an external 33.3-MHz crystal connected across the DEV_MXI and DEV_MXO
pins, along with two load capacitors, as shown in
. The external crystal load capacitors must be
connected only to the 33.3-MHz oscillator ground pin (DEV_V
SS
). Do not connect to board ground (V
SS
).
The DEV_DV
DD18
pin can be connected to the same 1.8 V power supply as DV
DDR2
.
Figure 7-7. 33.3-MHz System Oscillator
The load capacitors, C1 and C2, should be chosen such that the equation is satisfied (for typical values,
see
see
). 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 pins (DEV_MXI and DEV_MXO) and to the DEV_V
associated oscillator pins (DEV_MXI and DEV_MXO) and to the DEV_V
SS
pin.
Copyright © 2009–2012, Texas Instruments Incorporated
Peripheral Information and Electrical Specifications
149
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