LTC6930 LINER [Linear Technology], LTC6930 Datasheet - Page 10

• Manufacturer Part Number: LTC6930
• Description: 32.768kHz to 8.192MHz Precision ?Power Oscillators
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
LTC6930-X.XX
calculation for drift over 5 years at 30ppm/√kHr is as
follows:
hours = 43.830kHr
Drift calculations assume that the part is in continuous
operation during the entire time period of the calculation.
The movement of ions which results in drift is usually aided
by electric fi elds in the operating parts, and the typical drift
spec applies while the part is powered up. Conservative
calculations would use a tenth of the drift specifi cation for
time when power is not applied to the part.
Table 1. Frequency Setting and Available Frequencies
DIV Pin Settings
[DIVC][DIVB][DIVA]
LTC6930-4.19
LTC6930-5.00
LTC6930-7.37
LTC6930-8.00
LTC6930-8.19
10
5 years • 365.25 days/year • 24 hours/day = 43,830
√43.830kHr = 6.62√kHr
6.62√kHr • 30ppm/√kHr = 0.0198% over 5 years.
4.194304MHz 2.097152MHz 1.048576MHz
7.3728MHz
5.000MHz
8.000MHz
8.192MHz
000
÷1
3.6864MHz
2.500MHz
4.000MHz
4.096MHz
001
÷2
1.8432MHz
1.250MHz
2.000MHz
2.048MHz
010
÷4
524.288kHz
625.0kHz
921.6kHz
1000kHz
1024kHz
Setting the Frequency
The output frequency of the LTC6930 is chosen from the
values in Table 1 and set using the DIV pins, as noted
in the table. Master oscillator frequency is preset in the
factory, and the DIV pins select an internal binary divider
of up to 128.
For example, if the desired oscillator output frequency
is 2.5MHz, fi nding 2.5MHz in Table 1 shows that the
LTC6930-5.00 should be ordered, having a master oscil-
lator frequency of 5MHz, and a DIV value of [001] should
be used. This would equate to grounding DIVC and DIVB,
while connecting DIVA to the positive supply. Frequencies
other than those shown in Table 1 may be requested.
011
÷8
262.144kHz
312.5kHz
460.8kHz
500.0kHz
512.0kHz
÷16
100
131.072kHz
156.25kHz
230.4kHz
250.0kHz
256.0kHz
÷32
101
65.536kHz
78.125kHz
115.2kHz
125.0kHz
128.0kHz
÷64
110
39.0625kHz
32.768kHz
57.6kHz
62.5kHz
64.0kHz
÷128
111
6930fa