LMX1601SLB datasheet(12/14 Pages) NSC

12 / 14 page

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.

FoLD

OSC

OUT

3210

AUX_R[17]

AUX_R[16]

AUX_R[15]

AUX_R[14]

0000

Crystal Mode

0001

Crystal Mode

All Other States

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

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.

DS100129-18

DS100129-19

LMX1601SLB Datasheet(PDF) 12 Page - National Semiconductor (TI)