LMX1600 Datasheet, PDF (12/14 Pages) National Semiconductor (TI) – PLLatinum™ Low Cost Dual Frequency Synthesizer

2.0 Programming Description (Continued)
2.5.3 OSC Mode Programming
The OSC_out pin can be optimized for operating with an external crystal resonator or an external reference frequency source (i.e.
TCXO). If the application uses an external reference frequency source, the current dissipation of the LMX1600/01/02 can be re-
duced with the Logic Mode (0.5 mA typ.). Crystal Mode should be used when an external crystal resonator is used. Logic Mode
is used when an external reference frequency source is used. In Logic Mode, OSC_OUT should be connected to a 30 pF capacitor
to ground for optimum performance.
When the FoLD output state is selected to CMOS high/low levels, the OSC Mode is forced to Crystal Mode.
3
AUX_R[17]
0
0
FoLD
2
AUX_R[16]
0
0
All Other States
1
AUX_R[15]
0
0
0
AUX_R[14]
0
1
0
1
OSC_OUT
Crystal Mode
Crystal Mode
Logic Mode
Crystal Mode
2.5.4 Typical Crystal Oscillator Circuit
A typical implementation of a 10 MHz crystal oscillator with the OSC_OUT pin in Crystal Mode is shown below.
2.6 SERIAL DATA INPUT TIMING
DS100129-18
DS100129-19
Note 17: Data shifted into register on clock rising edge.
Data is shifted in MSB first.
TEST CONDITIONS: The Serial Data Input Timing is tested using a symmetrical waveform around V_CC/2. The test waveform has
an edge rate of 0.6 V/ns with amplitudes of 2.2V @ V_CC = 2.7V.
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