LTC6906CS6 Linear Technology, LTC6906CS6 Datasheet - Page 10

• Manufacturer Part Number: LTC6906CS6
• Manufacturer: Linear Technology
• Type: Silicon Oscillatorr

Specifications of LTC6906CS6

• Mounting Style: Surface Mount
• Screening Level: Industrial
• Product Length (mm): 2.9mm
• Product Depth (mm): 1.75mm
• Product Height (mm): 0.9mm
• Package / Case: TSOT-23
• Lead Free Status / RoHS Status: Not Compliant

LTC6906
Start-Up Time
When the LTC6906 is powered up, it holds the OUT pin
low. After the master oscillator has settled, the OUT pin
is enabled and the first output cycle is guaranteed to be
within specification. The time from power-up to the first
output transition is given approximately by:
The digital divider ratio, N, does not affect the start-up time.
Power Supply Rejection
The LTC6906 has a very low supply voltage coefficient,
meaning that the output frequency is nearly insensitive
to the DC power supply voltage. In most cases, this error
term can be neglected.
High frequency noise on the power supply (V
potential to interfere with the LTC6906’s master oscilla-
tor. Periodic noise, such as that generated by a switching
power supply, can shift the output frequency or increase
APPLICATIONS INFORMATION
10
t
START
Figure 12. Test Circuit with an Inductive Power Supply
3.3V
≅ 64 • t
3.5
2
1
0
3
4.65
330nH
Figure 13. Output Waveforms with
an Inductive Supply (See Figure 12)
L
S
OSC
4.75
V
GND
DIV
+
LTC6906
+ 100µs
4.85
GRD
OUT
SET
TIME (s)
C
C
C
C
LOAD
LOAD
LOAD
LOAD
4.95
= 5pF
= 10pF
= 20pF
= 50pF
6906 F12
R
100k
SET
5.05
C
LOAD
6906 F13
5.15
1MHz
+
) pin has the
jitter. The risk increases when the fundamental frequency
or harmonics of the noise fall near the master oscillator
frequency. It is relatively easy to filter the LTC6906 power
supply because of the very low supply current. For ex-
ample, an RC filter with R = 160Ω and C = 10µF provides
a 100Hz lowpass filter while dropping the supply voltage
only about 10mV.
Operating the LTC6906 with Supplies Higher Than 3.6V
The LTC6906 may also be used with supply voltages
between 3.6V and 5.5V under very specific conditions.
To ensure proper functioning above 3.6V, a filter circuit
must be attached to the power supply and located within
1cm of the device. A simple RC filter consisting of a 100Ω
resistor and 1µF capacitor (Figure 16) will ensure that sup-
ply resonance at higher supply voltages does not induce
unpredictable oscillator behavior. Accuracy under higher
supplies may be estimated from the typical Frequency vs
Supply Voltage curves in the Typical Performance Char-
acteristics section of this data sheet.
Figure 14. Test Circuit with a Resistive Power Supply
3.3V
3.5
1
0
3
2
0.4
Figure 15. Output Waveforms with
a Resistive Supply (See Figure 14)
100
R
S
0.5
V
GND
DIV
+
LTC6906
0.6
GRD
OUT
SET
0.7
TIME (s)
C
C
C
C
LOAD
LOAD
LOAD
LOAD
0.8
6906 F14
R
100k
= 5pF
= 10pF
= 20pF
= 50pF
SET
0.9
C
1.0
LOAD
6906 F15
1.1
1MHz
6906fb