LTC6900IS5#TRMPBF Linear Technology, LTC6900IS5#TRMPBF Datasheet - Page 8

• Manufacturer Part Number: LTC6900IS5#TRMPBF
• Description: IC OSC PREC LP RES SET TSOT23-5
• Manufacturer: Linear Technology
• Type: Oscillator, Siliconr

Specifications of LTC6900IS5#TRMPBF

• Frequency: 20MHz
• Voltage - Supply: 2.7 V ~ 5.5 V
• Current - Supply: 920µA
• Operating Temperature: -40°C ~ 85°C
• Package / Case: TSOT-23-5, TSOT-5, TSOP-5
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Count: -
• Other names: LTC6900IS5#PBF; LTC6900IS5#PBF; LTC6900IS5#TRMPBF; LTC6900IS5#TRMPBFTR

LTC6900
APPLICATIONS INFORMATION
POWER SUPPLY REJECTION
Low Frequency Supply Rejection (Voltage Coeffi cient)
Figure 5 shows the output frequency sensitivity to power
supply voltage at several different temperatures. The
LTC6900 has a guaranteed voltage coeffi cient of 0.1%/V
but, as Figure 5 shows, the typical supply sensitivity is
twice as low.
High Frequency Power Supply Rejection
The accuracy of the LTC6900 may be affected when its
power supply generates signifi cant noise with a frequency
content in the vicinity of the programmed value of f
switching power supply is used to power the LTC6900, and
if the ripple of the power supply is more than 20mV, make
sure the switching frequency and its harmonics are not
related to the output frequency of the LTC6900. Otherwise,
the oscillator may show additional frequency error.
If the LTC6900 is powered by a switching regulator and
the switching frequency or its harmonics coincide with
the output frequency of the LTC6900, the jitter of the
oscillator output may be affected. This phenomenon will
become noticeable if the switching regulator exhibits
ripples beyond 30mV.
8
–0.05
0.15
0.10
0.05
0
2.5
R
PIN 4 = FLOATING (÷10)
SET
Figure 5. Supply Sensitivity
3.0
= 63.2k
SUPPLY VOLTAGE (V)
3.5
4.0
4.5
–40°C
25°C
5.0
85°C
6900 F05
5.5
OSC
. If a
START-UP TIME
The start-up time and settling time to within 1% of the
fi nal value can be estimated by t
+ 10μs. Note the start-up time depends on R
independent from the setting of the divider pin. For in-
stance with R
of its 200kHz fi nal value (N = 10) in approximately 380μs.
Figure 6 shows start-up times for various R
Figure 7 shows an application where a second set resistor
R
switch S1. When switch S1 is open, the output frequency
of the LTC6900 depends on the value of the resistor R
When switch S1 is closed, the output frequency of the
LTC6900 depends on the value of the parallel combination
of R
The start-up time and settling time of the LTC6900 with
switch S1 open (or closed) is described by t
above. Once the LTC6900 starts and settles, and switch
S1 closes (or opens), the LTC6900 will settle to its new
output frequency within approximately 70μs.
Jitter
The Peak-to-Peak Jitter vs Output Frequency graph, in the
Typical Performance Characteristics section, shows the
typical clock jitter as a function of oscillator frequency and
power supply voltage. The capacitance from the SET pin,
(Pin 3), to ground must be less than 10pF . If this require-
ment is not met, the jitter will increase.
SET2
SET1
is connected in parallel with set resistor R
and R
–10
60
50
30
20
10
70
40
0
0
SET
SET2
20k
= 100k, the LTC6900 will settle with 1%
TIME AFTER POWER APPLIED (μs)
Figure 6. Start-Up Time
63.2k
200
.
400
400k
600
START
T
V
800
A
+
= 25°C
= 5V
≅ R
6900 F06
1000
SET
SET
START
SET
(3.7μs/kΩ)
resistors.
and it is
SET1
shown
SET1
6900fa
via
.