RF2905 データシートの表示（PDF） - RF Micro Devices

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RF2905

433/868/915MHZ FM/FSK/ASK/OOK TRANSCEIVER

RF Micro Devices 

RF2905

Pin Function Description

1

RX ENABL Enable pin for the receiver circuits. RX ENABL>2.0V powers up all

receiver functions. RX ENABL<1.0V turns off all receiver functions

except the PLL functions and the RF mixer.

Interface Schematic

RX ENABL

50 kΩ

2

TX ENABL Enables the transmitter circuits. TX ENABL>2.0V powers up all trans-

20 kΩ

mitter functions. TX ENABL<1.0V turns off all transmitter functions

TX ENABL

except the PLL functions.

40 kΩ

3

TX OUT RF output pin for the transmitter electronics. TX OUT output impedance

is a low impedance when the transmitter is enabled. TX OUT is a high

impedance when the transmitter is disabled.

4

GND2

Ground connection for the 40dB IF limiting amplifier and Tx PA func-

tions. Keep traces physically short and connect immediately to ground

plane for best performance.

5

RX IN

RF input pin for the receiver electronics. RX IN input impedance is a

low impedance when the transmitter is enabled. RX IN is a high imped-

ance when the receiver is disabled.

VCC

20

TX OUT

RX IN

500

6

GND1

Ground connection for RF receiver functions. Keep traces physically

short and connect immediately to ground plane for best performance.

7

LNA OUT Output pin for the receiver RF low noise amplifier. This pin is an open

collector output and requires an external pull up coil to provide bias and

tune the LNA output.

8

GND3

Same as pin 4.

9

MIX IN

RF input to the RF Mixer. An LC matching network between LNA OUT

and MIX IN can be used to connect the LNA output to the RF mixer

input in applications where an image filter is not needed or desired.

VCC

MIX IN

LNA OUT

GND5

10

GND5

GND5 is the ground connection shared by the input stage of the trans-

mit power amplifier and the receiver RF mixer.

11

MIX OUT+ Complementary (with respect to pin 12) IF output from the RF mixer.

MIX OUT+

Interfaces directly to 10.7MHz ceramic IF filters as shown in the appli-

MIX OUT-

cation schematic. A pull-up inductor and series matching capacitor

should be used to present a 330Ω termination impedance to the

ceramic filter. Alternately, an IF tank can be used to tailor the IF fre-

quency and bandwidth to meet the needs of a given application.

15 pF

GND5

15 pF

GND5

12

MIX OUT- IF output from the RF mixer. For a balanced mixer output, pull-up induc- See pin 11.

tors from pin 11 and 12 to VCC and a capacitor between the pins should

be used. The sum of the total pull-up inductance should be used to res-

onate the capacitor between pins 11 and 12. DC blocking capacitors of

10nF can then be used to connect the balanced output to IF1 IN+ (pin

13) and IF1 IN- (pin 14).

11

Rev B11 010516

11-57

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