CLOCK GENERATOR
An internal 3.3v crystal oscillator or an external
The X2 pin is the 24MHz crystal driver and
should not be used to drive any other device.
This pin should be left unconnected if an
external clock is used and INT_OSC is “0”.
oscillator source is required for the CAM35C44
(FIGURE 3). The crystal/clock pins and buffer
types are shown in TABLE 1.
The 24MHz crystal can be used to directly drive
The X1/CLK1 and X2 pins provide an external
connection for a parallel resonant 24MHz crystal.
Configuration register CR08 bit 5, INT_OSC,
must be set to “1” to configure the internal
oscillator for this arrangement (see the section
CRO8 - Power Control on page 27).
the ACE block.
This saves power when
115.2Kbps or slower data transfers are required
because the PLL and SCE block do not need to
be powered. See TABLE 25 and the section
CRO8 - Power Control on page 27.
An external CMOS compatible oscillator is
required if a 24MHz crystal is not used. In this
case INT_OSC must be set to “0”.
FIGURE 3 - EXAMPLE 24MHz OSCILLATOR CIRCUIT
CAM35C44
X1/CLK1
X2
24MHz CRYSTAL
12
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