11-133
RF2917
Rev B2 010118
11
Pin
Function
Description
Interface Schematic
16
IF2 IN
Inverting input to the 60dB limiting amplifier strip. A 10 nF DC blocking
capacitor is required on this input. The IF2 IN input presents a nominal
330
Ω input resistance and interfaces directly to 10.7MHz ceramic fil-
ters.
17
IF2 BP+
DC feedback node for the 60dB limiting amplifier strip. A 100nF bypass
capacitor from this pin to ground is required.
See pin 16.
18
IF2 BP-
See pin 17.
See pin 16.
19
VCC3
This pin is used to supply DC bias to the 60dB IF limiting amplifier. An
IF bypass capacitor should be connected directly to this pin and
returned to ground. A 10 nF capacitor is recommended for 10.7MHz IF
applications.
20
MUTE
This pin is used to select FM, FSK, or mute at the FM OUT pin.
MUTE> Vcc - 0.4V turns the FM OUT signal off. MUTE< 0.4V turns the
FM OUT signal on for FSK digital data. When MUTE is left floating, the
FM OUT signal is linear FM.
21
RSSI
A DC voltage proportional to the received signal strength is output from
this pin. The output voltage increases with increasing signal strength.
22
FM OUT
Demodulated output from the discriminator/demodulator. Output levels
on this are CMOS compatible in FSK mode (see pin 20). In linear FM
mode, the demodulated signal level is approximately 240mVpp on a
DC voltage offset. The magnitude of the load impedance is intended to
be 1M
Ω or greater.
23
IF2 OUT
IF output from the 60dB limiting amplifier strip. This pin is intended to
be connected to pin 24 through a 5pF capacitor (for 10.7MHz IF appli-
cations). This capacitor in conjunction with a tank resonant at the IF fre-
quency connected from pin 24 to ground is used to form an FM
discriminator.
24
DEMOD IN
This pin is the input to the FM demodulator. This pin is NOT AC cou-
pled. Therefore, a DC blocking capacitor is required on this pin to avoid
a DC path to ground. A DC blocked LC tank resonant at the IF or
ceramic discriminator should be connected to this pin.
25
RESNTR-
This port is used to supply DC voltage to the VCO as well as to tune the
center frequency of the VCO. Equal value inductors should be con-
nected to this pin and pin 26.
26
RESNTR+
See pin 25.
See pin 25.
27
VCC2
This pin is used to supply DC bias to the VCO, prescaler, and PLL. An
IF bypass capacitor should be connected directly to this pin and
returned to ground. A 10nF capacitor is recommended for 10.7MHz IF
applications.
28
GND4
GND4 is the ground shared on chip by the VCO, prescaler, and PLL
electronics.
IF2 IN
330
330
60 k
Ω
60 k
Ω
IF2 BP+
IF2 BP-
MUTE
V
CC
V
CC
RSSI
IF2 OUT
DEMOD IN
10 k
Ω
V
CC
RESNTR-
RESNTR+
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