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RC6516
PRODUCT SPECIFICATION
3
P
Pin Assignments
Pin Descriptions
Pin Name
AFC+, AFC–
AFCSWT
Pin Number
18, 17
8
Description
Inputs to the limiter that sets the polarity of the third multiplier in the FPLL loop.
This digital input is LO during normal operation. A TTL/CMOS high input
enable the crystal oscillator and an extra I-channel charge pump, while
disabling the IF input sections. The crystal oscillator outputs are switched into
the input ports of the quadrature mixers. The VCO then locks to 4 x crystal
frequency.
An internal charge pump will develop a voltage across any capacitance on this
pin. Voltage on this node directly determines the front end IF gain. When
operating on a 12 volt supply, moving this voltage from 9V to 2V reduces the
gain by at least 40dB.
The input voltage on this pin determines the transition point for delayed AGC.
A TTL/CMOS high level input on this pin activates internal charge up to
decrease the voltage on the CAGC pin.
Ground line for backend. Also the substrate connection to the IC. Should be at
the lowest potential to the IC.
Ground line for digital section.
Shield ground for input.
Ground signals for front end sections.
A TTL/CMOS high level input on this pin activates internal charge up to
increase the voltage on the CAGC pin.
Demodulated & filtered output to be ac coupled to A/D converter.
Demodulated output before filtering. DC coupled back to AFC limiter inputs
AFC+/AFC– though an external low pass filter.
IF inputs to be demodulated. Internal dc restoration. External ac coupling
required. Usually interfaced to a SAW filter.
Charge pump output from third multiplier. This output can be fed to an external
lead-lag filter to develop the voltage required to drive the varactor in feedback
till a lock is established with the pilot.
C
AGC
4
DLYADJ
G
DN
25
7
GND2
22
GND3
GNDN
GNDP
G
UP
11
27
2
6
IDAT+
IMX+, IMX–
21
20, 19
IN+, IN–
28, 1
PDO
15
5
6
7
8
9
10
11
DLY ADJ
RFILT
VCC2 (12V)
GND2
IDAT+
IMX+
IMX–
1
1
1
1
1
1
1
C
A
V
G
I
I
G
T
4
3
2
1
2
2
2
V
V
V
P
Q
A
A
A
25
24
23
22
21
20
19
65-3686-01
SHUT DOWN
G
UP
G
DN
AFCSWT
XTL1
XTL2
GND3