Datasheet LTC6905 (Analog Devices) - 5

LTC6905
TYPICAL PERFORMANCE CHARACTERISTICS ROUT vs V+ Jitter vs Frequency Frequency vs Temperature
45 1.20 1.0 40 0.8 1.00 0.6 35 ÷4 ÷2 ÷1 0.4 30 0.80 0.2 25 0.60 0 20 –0.2 15 0.40 –0.4 OUTPUT RESISTANCE (Ω) 10 PEAK-TO-PEAK JITTER (%) PERCENTAGE ERROR (%) –0.6 0.20 5 –0.8 0 0 –1.0 2.5 3 3.5 4 4.5 5 5.5 0 20 40 60 80 100 120 140 160 180 –40 –20 0 20 40 60 80 100 120 SUPPLY VOLTAGE (V) FREQUENCY (MHz) TEMPERATURE (°C) 6905 G04 6905 G05 6905 G08
LTC6905 Output Operating at LTC6905 Output Operating at 17.5MHz, VS = 3V 170MHz, VS = 3V
1V/DIV 1V/DIV 12.5ns/DIV 6905 G06 1ns/DIV 6905 G07
PIN FUNCTIONS V+ (Pin 1):
Voltage Supply (2.7V ≤ V+ ≤ 5.5V). This sup- of N in the frequency equation. Pin 4 should be tied to V+ ply must be kept free from noise and ripple. It should be for the ÷1 setting, the highest frequency range. Floating bypassed directly to the GND (Pin 2) with a 0.1μF capaci- Pin 4 divides the master oscillator by 2. Pin 4 should tor or higher. be tied to GND for the ÷4 setting, the lowest frequency
GND (Pin 2):
Ground. Should be tied to a ground plane range. To detect a fl oating DIV pin, the LTC6905 attempts for best performance. to pull the pin toward midsupply. This is realized with two internal current sources, one tied to V+ and Pin 4 and the
SET (Pin 3):
Frequency-Setting Resistor Input. The value other one tied to ground and Pin 4. Therefore, driving of the resistor connected between this pin and V+ deter- the DIV pin high requires sourcing approximately 15μA. mines the oscillator frequency. The voltage on this pin is Likewise, driving DIV low requires sinking 11μA. When held by the LTC6905 to approximately 1V below the V+ Pin 4 is fl oated, it should be bypassed by a 1nF capacitor voltage. For best performance, use a precision metal fi lm to ground or it should be surrounded by a ground shield resistor with a value between 10k and 25k and limit the to prevent excessive coupling from other PCB traces. capacitance on this pin to less than 10pF.
OUT (Pin 5):
Oscillator Output. This pin can drive 5kΩ
DIV (Pin 4):
Divider-Setting Input. This three-state input and/or 5pF loads. For larger loads, refer to the Applications selects among three divider settings, determining the value Information section. 6905fd 5