LT1394 Linear Technology, LT1394 Datasheet - Page 16

• Manufacturer Part Number: LT1394
• Description: 4ns/ 150MHz Dual Comparator with Independent Input/Output Supplies
• Manufacturer: Linear Technology

RELATED PARTS
LT1394
Voltage-Controlled Crystal Oscillator (VCXO)
Figure 20, a variant of the basic crystal oscillator, permits
voltage tuning the output frequency. Such voltage-con-
trolled crystal oscillators (VCXO) are often employed
where slight variation of a stable carrier is required. This
example is specifically intended to provide a 4 NTSC
sub-carrier tunable oscillator suitable for phase locking.
The LT1394 is set up as a crystal oscillator, operating
similarly to Figure 3 (a). The varactor diode is biased from
the tuning input. The tuning network is arranged so a 0V
to 5V drive provides a reasonably symmetric, broad tuning
range around the 14.31818MHz center frequency. The
indicated selected capacitor sets tuning bandwidth. It
should be picked to complement loop response in phase
locking applications. Figure 21 is a plot of tuning input
voltage versus frequency deviation. Tuning deviation from
the 4 NTSC 14.31818MHz center frequency exceeds
PART NUMBER
LT1016
LT1116
LT1671
LT1720
16
TYPICAL
240ppm for a 0V to 5V input.
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] FAX: [phone] www.linear-tech.com
APPLICATION
DESCRIPTION
UltraFast Precision Comparator
12ns Single Supply Ground-Sensing Comparator
Fast Single Supply Comparator
UltraFast Dual Single Supply Comparator
Figure 20. A 4 NTSC Sub-Carrier Voltage-Tunable Crystal Oscillator. Tuning Range
and Bandwidth Accommodate Variety of Phase Locked Loops
390
2k
5V
100pF
200pF
1M
1M
+
–
LT1394
U
MV-209
Y1**
15pF
2k
†
C SELECT***
0.047 F
100pF
1M
*** C SELECT SETS TUNING BANDWIDTH. SET TO COMPLEMENT
** NORTHERN ENGINEERING LABS C-2350N-14.31818MHz
* 1% FILM RESISTOR
†
VARACTOR DIODE
LOOP RESPONSE IN PHASE LOCKING APPLICATIONS
1M*
1N4148
Figure 21. Control Voltage vs Output Frequency for Figure 15.
Tuning Deviation from Center Frequency Exceeds 240ppm
5V
47k*
LT1004-2.5
9
8
7
6
5
4
3
2
1
0
COMMENTS
Industry Standard 10ns Comparator
Single Supply Version of LT1016
60ns, 450 A Single Supply Comparator
Dual 4.5ns, 4mA Single Supply Comparator
0
14.31818MHz
1k*
14.314.0MHz
3.9k*
1
INPUT VOLTAGE (V)
V
0V TO 5V
FREQUENCY
OUTPUT
IN
2
LINEAR TECHNOLOGY CORPORATION 1998
1394 F20
3
14.3217MHz
1394f LT/TP 0499 4K • PRINTED IN USA
4
1394 F21
5