RFRXD0420T-I/LQ Microchip Technology, RFRXD0420T-I/LQ Datasheet - Page 7

• Manufacturer Part Number: RFRXD0420T-I/LQ
• Description: IC RCVR 315/433MHZ ASK/FSK32LQFP
• Manufacturer: Microchip Technology

Specifications of RFRXD0420T-I/LQ

• Frequency: 300MHz ~ 450MHz
• Sensitivity: -106dBm
• Data Rate - Maximum: 80 kbps
• Modulation Or Protocol: ASK, FM, FSK
• Applications: Home Automation, Remote Sensing, RKE
• Current - Receiving: 9.2mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 2.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-LQFP
• For Use With: DV164102 - KIT DEV RFPICKIT KIT 1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Memory Size: -

employed in this design because it can handle a larger
dynamic range while consuming less power with simple
circuitry than AGC circuitry.
The internal resistance of the 2IF
2.2 kΩ. In order to terminate ceramic IF filters whose
output impedance is 330 Ω, a 390 Ω resistor can be
paralleled to the 2IF
FBC1 (Pin 12) and FBC2 (Pin 13) are connected to
external feedback capacitors.
The IF Limiting Amplifier pins are illustrated in
Figures 2-7 and 2-8.
FIGURE 2-7:
FIGURE 2-8:
2.5.2
The RSSI signal is proportional to the log of the signal
at 2IF
40 µV to 160 mV. The slope of the RSSI output is
approximately 26 mV/dB of RF signal.
The RSSI output has an internal 36 kΩ resister to Vss
fed by a current source. This resistor converts the
RSSI current to voltage.
For Amplitude Shift Keying (ASK) demodulation, RSSI
is compared to a reference voltage (static or dynamic).
Post detector filtering is easily implemented by
connecting a capacitor to ground from the RSSI pin
effectively creating an RC filter with the internal 36 kΩ
resistor.
 2003 Microchip Technology Inc.
IN
. The 2IF
2IF
11
13
FBC2
IN
INDICATOR (RSSI)
RECEIVED SIGNAL STRENGTH
V
V
V
V
DD
SS
DD
SS
IN
2IF
15
BLOCK DIAGRAM OF IF
LIMITING AMPLIFIER INPUT
PINS
BLOCK DIAGRAM OF IF
LIMITING AMPLIFIER OUTPUT
PIN
OUT
input RSSI range is approximately
IN
2.2 kΩ
and FBC2 pins.
V
V
DD
SS
Vss
V
V
2.2 kΩ
200 µA
DD
SS
IN
40 µA
pin is approximately
V
V
DD
SS
FBC1
12
Preliminary
For FSK and FM demodulation, the RSSI represents
the received signal strength of the incoming RF signal.
The RSSI pin is illustrated in Figure 2-9.
FIGURE 2-9:
2.6
The demodulator (DEMOD) section consists of a phase
detector (MIXER2) and amplifier creating a quadrature
detector (also known as a phase coincidence detector)
to demodulate the IF signal in FSK and FM modulation
applications. The quadrature detector provides all the
IF functions required for FSK and FM demodulation
with only a few external parts.
The in-phase signal comes directly from the output of
the IF limiting amplifier to MIXER2. The quadrature
signal is created by an external tuned circuit from the
output of the IF limiting amplifier (2IF
coupled to the MIXER2 DEM
impedance of the DEM
The external tuned circuit can be constructed from sim-
ple inductor-capacitor (LC) components but will require
one of the elements to be tunable. A no-tune solution
can be constructed with a ceramic discriminator.
The output voltage of the DEMOD amplifier (DEMout+
and DEMout-, Pins 23 and 24) depends on the peak
deviation of the FSK or FM signal and the Q of the
external tuned circuit. DEMout+ and DEMout- are high
impedance outputs with only a 20 µA current capability.
The Demodulator pins are illustrated in Figures 2-10
and 2-11.
FIGURE 2-10: BLOCK DIAGRAM OF
Demodulator
rfRXD0420/0920
DEM
21
16
RSSI
BLOCK DIAGRAM OF RSSI
PIN
DEMODULATOR INPUT PIN
IN
V
V
V
V
DD
SS
DD
SS
IN
pin is approximately 47 kΩ.
50 Ω
V
IN
DD
(Pin 16) input. The input
47 kΩ
V
SS
36 kΩ
I (Pi)
V
OUT
DD
DS70090A-page 7
, Pin 15) AC-