Datasheet

34
LTC2420
TYPICAL APPLICATIO S
U
U1-A U1-B U1-C
U1-F
U1-E
TO LTC2420
F
O
PIN
U1-D
12
5pF
5k
1k
2N3904
10k
47k
1k
47k
10pF
100smps, F
O
= 2.048MHz
30smps, F
O
= 614.4kHz
U1: 74HC14 OR EQUIVALENT
270pF
345 6
12 13
HALT
11 10
9 8
2420 F40
Figure 40. 2.048MHz Oscillator for 100sps Output Rate
2.048MHz Oscillator for 100sps Output Ratio
The oscillator circuit shown in Figure 40 can be used to
drive the F
O
pin, boosting the conversion rate of the
LTC2420 for applications that do not require a notch at
50Hz or 60Hz. This oscillator is not sensitive to hysteresis
voltage of a Schmitt trigger device as are simpler
relaxation oscillators using the 74HC14 or similar de-
vices. The circuit can be tuned over a 3:1 range with only
one resistor and can be gated. The use of transmission
gates could be used to shift the frequency in order to
provide setable conversion rates.