Datasheet

LTC6902
15
6902f
Figure 7. Start-Up Time
TIME AFTER POWER APPLIED (µs)
0
FREQUENCY ERROR (%)
20
30
40
600
400k
1000
69012 F07
10
0
–10
200 400 800
50
60
70
63.2k
20k
T
A
= 25°C
V
+
= 5V
POWER SUPPLY SENSITIVITY
Figure 6 shows the output frequency sensitivity to power
supply voltage at several different temperatures. The
LTC6902 has a guaranteed voltage coefficient of 0.1%/V
but, as Figure 6 shows, the typical supply sensitivity is
twice as low.
START-UP TIME
The start-up time and settling time to within 1% of the final
value can be estimated by t
START
≅ R
SET
(3.7µs/kΩ) +
10µs. Note the start-up time depends on R
SET
and is
independent from the setting of the divider pin. For in-
stance with R
SET
= 100k, the LTC6902 will settle with 1%
of its 200kHz final value (N = 10) in approximately 380µs.
Figure 7 shows start-up times for various R
SET
resistors.
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.
APPLICATIO S I FOR ATIO
WUUU
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
Figure 6. Supply Sensitivity
SUPPLY VOLTAGE (V)
2.5
–0.05
FREQUENCY DEVIATION (%)
0
0.05
0.10
0.15
3.0 3.5 4.0 4.5
69012 F06
5.0 5.5
85°C
–40°C
25°C
R
SET
= 63.2k
PIN 4 = FLOATING (÷10)