3

FX489DW

FX489P

13

14

15

16

17

18

19

20

21

22

23

24

Pin Number

Function

Doc1:

Connections to the Rx Level Measurement Circuitry. A capacitor should be connected from

each pin to V

Doc2:

BT: A logic level to select the modem ‘BT’ (the ratio of the Tx Filter's -3dB frequency to the Bit-

Rate). A logic “1” sets the modem to a BT of 0.5, a logic “0” to a BT of 0.3.

Tx Out: The Tx signal output from the FX489 GMSK Modem.

Tx Enable: A logic “1” applied to this input enables the transmit data path through the Tx Filter to

the “Tx Out pin”. A logic “0” will put the “Tx Out” pin to V

Tx PS: A logic “1” applied to this input will powersave all transmit circuits except for the Tx Clock.

Tx Data: The logic level input for the data to be transmitted. This data should be synchronous

with the “Tx Clock”.

Rx Data: A logic level output carrying the received data, synchronous with the “Rx Clock”.

Rx Clock: A logic level clock output at the received data bit-rate.

Tx Clock: A logic level clock output at the transmit-data rate.

Rx S/N: A logic level output which may be used as an indication of the quality of the received

signal.

V

Positive supply rail. A single +5 volt power supply is required. Levels and voltages within this

modem are dependent upon this supply. This pin should be decoupled to V

mounted close to the pin.