TH72035

868/915MHz

FSK/ASK Transmitter

39010 72035

Page 6 of 20

Data Sheet

Rev. 011

Jan/12

2.8

Mode Control Logic

The mode control logic allows two different

modes of operation as listed in the following

table. The mode control pin ENTX is pulled-

down internally. This guarantees that the whole

circuit is shut down if this pin is left floating.

ENTX

Mode

Description

0

TX standby

TX disabled

1

TX active

TX enable

2.9

Timing Diagrams

transmitter start-up time. The crystal oscillator starts oscillation and the PLL locks to the desired output fre-

and then the RF carrier can be FSK or ASK modulated.

Fig. 5:

Timing diagrams for FSK and ASK modulation

RF carrier

low

low

high

high

LOCK

FSKDTA

t

low

high

ENTX

low

low

high

high

LOCK

ASKDTA

t

low

high

ENTX