NJ88C30 View Datasheet(PDF) - Zarlink Semiconductor Inc
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Description
Manufacturer
NJ88C30 Datasheet PDF : 9 Pages
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Once the phase difference exceeds 2π, the comparator will
gain or slip one cycle and then try to lock on to the new zero
phase difference. Note that very narrow pulses may be seen on
the inactive phase comparator output at the end of the pulse on
the active output, as shown in Fig. 6.
Data Input and Control Register
To control the synthesiser a simple three-line serial input is
used with DATA, CLOCK and DATA TRANSFER signals. The
data consists of 19 bits; the first three, DR2, DR1 and DR0,
control the reference divider while the following sixteen, DF15
LOCK DETECT (LD)
NJ88C30
to DF0, control the prescaler and programmable divider. Until
the synthesiser receives the DATA TRANSFER pulse, it will
use the previously loaded data; on receiving the pulse it will
switch rapidly to the new data.
APPLICATIONS
A simplified circuit for a synthesiser intended for VHF
broadcast receiver applications is shown in Fig. 8. When the
varicap line drive voltage necessary to tune the required band
is greater than 5V, some form of level shifter such as the
operational amplifier shown in Fig. 8 is required.
DATA TRANSFER
CLOCK
DATA
4·5MHz
5 - 65p
1
14
2
13
3
12
4 NJ88C30 11
5
10
6
9
7
8
R1 18k
R1' 18k
22k
10n
R2
10k
C1
47n
112V
1
SL562
2
10k
22k
22k
VARICAP DRIVE
10n
1 -10V
VCO
112V
15V
Fig.8. Typical application
PROGRAMMING EXAMPLE
1.Maximum Frequency
For a channel spacing (comparison frequency, fcomp) of
5kHz when using a 10MHz crystal oscillator, the reference
divider ratio will need to be 2000 (seeTable 1) This is
programmed as binary 100 (= 4HEX) in the most significant
three of the 19 bits (MSB programmed first).
To obtain the maximum VCO frequency of 200MHz the
programmable divider ratio would be:
2003106
53103
=
403103
which
is
9C40HEX
The program word would then be as shown in Table 2.
DR
DF
2 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Binary
1001001110001000000
Hex
4
9
C
4
0
Table 2 Maximum VCO frequency programming (fXTAL = 10MHz, fcomp = 5kHz)
2. Minimum Frequency
Using the same crystal frequency and channel spacing
(10MHz, 5kHz), the lower limit of programmable divider ratio of
240 = F0HEX gives a minimum programmable VCO frequency
of 240353103 = 1·2MHz. The program word for this frequency
is therefore as shown in Table 3.
DR
DF
2 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Binary
1000000000011110000
Hex
4
0
0
F
0
Table 3 MinimumVCO frequency programming (fXTAL = 10MHz, fcomp = 5kHz)
5
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