LTC6905

4

6905fa

LTC6905 Output Operating at

LTC6905 Output Operating at

Jitter vs Frequency

SUPPLY VOLTAGE (V)

2.5

0

5

15

20

25

4.5

45

6905 G04

10

3.5

3

5

4

5.5

30

35

40

FREQUENCY (MHz)

0

0

0.20

0.60

÷4

÷2

÷1

0.80

1.00

40

80 100

180

6905 G05

0.40

20

60

120 140 160

1.20

12.5ns/DIV

6905 G06

1ns/DIV

6905 G07

TYPICAL PERFOR A CE CHARACTERISTICS

TEMPERATURE (°C)

–40

–1.0

–0.8

–0.4

–0.2

0

1.0

0.4

0

40

60

6905 G08

–0.6

0.6

0.8

0.2

–20

20

80

100 120

Frequency vs Temperature

PI FU CTIO S

must be kept free from noise and ripple. It should be

bypassed directly to the GND (Pin 2) with a 0.1µF capacitor

or higher.

GND (Pin 2): Ground. Should be tied to a ground plane for

best performance.

SET (Pin 3): Frequency-Setting Resistor Input. The value

mines the oscillator frequency. The voltage on this pin is

voltage. For best performance, use a precision metal film

resistor with a value between 10k and 25k and limit the

capacitance on this pin to less than 10pF.

DIV (Pin 4): Divider-Setting Input. This three-state input

selects among three divider settings, determining the value

for the ÷1 setting, the highest frequency range. Floating Pin

4 divides the master oscillator by 2. Pin 4 should be tied to

GND for the÷4setting,thelowestfrequencyrange.Todetect

a floating DIV pin, the LTC6905 attempts to pull the pin

toward midsupply. This is realized with two internal current

ground and Pin 4. Therefore, driving the DIV pin high re-

quires sourcing approximately 15µA. Likewise, driving DIV

low requires sinking 15µA. When Pin 4 is floated, it should

be bypassed by a 1nF capacitor to ground or it should be

surrounded by a ground shield to prevent excessive cou-

pling from other PCB traces.

OUT (Pin 5): Oscillator Output. This pin can drive 5kΩ

and/or 5pF loads. For larger loads, refer to the Applications

Information section.

1V/DIV

1V/DIV