11-58
RF2905
Rev B11 010516
11
Pin
Function
Description
Interface Schematic
13
IF1 IN+
Balanced IF input to the 40dB limiting amplifier strip. A 10nF DC block-
ing capacitor is required on this input.
14
IF1 IN-
Functionally the same as pin 13 except inverting node amplifier input.
In single-ended applications, this input should be bypassed directly to
ground through a 10nF capacitor.
See pin 13.
15
IF1 BP+
DC feedback node for the 40dB limiting amplifier strip. A 10nF bypass
capacitor from this pin to ground is required.
See pin 13.
16
IF1 BP-
Same as pin 15.
See pin 13.
17
IF1 OUT
IF output from the 40dB limiting amplifier. The IF1 OUT output presents
a nominal 330
Ω output resistance and interfaces directly to 10.7MHz
ceramic filters.
18
IF2 IN
Balanced IF input to the 60dB limiting amplifier strip. A 10nF DC block-
ing capacitor is required on this input. The IF2 IN input presents a nom-
inal 330
Ω input resistance and interfaces directly to 10.7MHz ceramic
filters.
19
GND6
Ground connection for 60dB IF limiting amplifier. Keep traces physically
short and connect immediately to ground plane for best performance.
20
VREF IF
DC voltage reference for the IF limiting amplifiers. A 10nF capacitor
from this pin to ground is required.
21
IF2 BP+
DC feedback node for the 60dB limiting amplifier strip. A 10nF bypass
capacitor from this pin to ground is required.
See pin 18.
22
IF2 BP-
Same as pin 21.
See pin 18.
23
MUTE
This pin is used to mute the data output (DATA OUT). MUTE > 2.0V
turns the DATA OUT signal on. MUTE <1.0V turns the DATA OUT sig-
nal off. The MUTE signal should be logic low in the Sleep Mode.
24
RSSI
A DC voltage proportional to the received signal strength is output from
this pin. The output voltage range is 0.5V to 2.5V, into 51k
Ω load, and
increases with increasing signal strength.
25
FM OUT
Linear output from the FM demodulator. This pin is used in analog
applications when signal fidelity is important. This output is inverted for
low side injection of the LO and normal for high side injection.
26
DATA OUT
Demodulated data output from the demodulator. Output levels on this
are TTL/CMOS compatible. The magnitude of the load impedance is
intended to be 1M
Ω or greater. When using a RF2905 transmitter and
receiver back to back a data inversion will occur, when the LO is low
side injected. A high side injection will add an inversion of the Rx data.
IF1 IN-
IF1 IN+
330
330
60 k
Ω
60 k
Ω
IF1 BP+
IF1 BP-
IF1 OUT
IF2 IN
330
330
60 k
Ω
60 k
Ω
IF2 BP+
IF2 BP-
25 k
Ω
75 k
Ω
MUTE
V
CC
RSSI
FM OUT
DATA OUT
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