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RF2917

433/868/915MHZ FM/FSK RECEIVER

RF Micro Devices 

RF2917

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

330Ω input resistance and interfaces directly to 10.7MHz ceramic fil-

ters.

IF2 BP+

60 kΩ

330

IF2 BP-

60 kΩ

330

IF2 IN

17

IF2 BP+ DC feedback node for the 60dB limiting amplifier strip. A 100nF bypass See pin 16.

capacitor from this pin to ground is required.

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.

VCC

MUTE

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 1MΩ 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.

VCC

RSSI

IF2 OUT

VCC

DEMOD IN

10 kΩ

25

RESNTR- This port is used to supply DC voltage to the VCO as well as to tune the

RESNTR+

center frequency of the VCO. Equal value inductors should be con-

nected to this pin and pin 26.

RESNTR-

11

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.

Rev B2 010118

11-133

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