LTC6905CS5(RevA) View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
LTC6905CS5 Datasheet PDF : 8 Pages
| |||
LTC6905
TYPICAL PERFOR A CE CHARACTERISTICS
ROUT vs V+
45
40
35
30
25
20
15
10
5
0
2.5 3 3.5 4 4.5
SUPPLY VOLTAGE (V)
5 5.5
6905 G04
Jitter vs Frequency
1.20
1.00
÷4 ÷2
÷1
0.80
0.60
0.40
0.20
0
0 20 40 60 80 100 120 140 160 180
FREQUENCY (MHz)
6905 G05
Frequency vs Temperature
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
–40 –20 0 20 40 60 80 100 120
TEMPERATURE (°C)
6905 G08
LTC6905 Output Operating at
17.5MHz, VS = 3V
LTC6905 Output Operating at
170MHz, VS = 3V
1V/DIV
1V/DIV
12.5ns/DIV
6905 G06
1ns/DIV
6905 G07
PI FU CTIO S
V+ (Pin 1): Voltage Supply (2.7V ≤ V+ ≤ 5.5V). This supply
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
of the resistor connected between this pin and V+ deter-
mines the oscillator frequency. The voltage on this pin is
held by the LTC6905 to approximately 1V below the V+
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
4
of N in the frequency equation. Pin 4 should be tied to V+
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 ÷4 setting, the lowest frequency range. To detect
a floating DIV pin, the LTC6905 attempts to pull the pin
toward midsupply. This is realized with two internal current
sources, one tied to V+ and Pin 4 and the other one tied to
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.
6905fa
Share Link: 