TDA7110 Datasheet, PDF (15/39 Pages) Infineon Technologies AG – ASK/FSK Transmitter 868/433 MHz

TDA7110
Functional Description
To achieve FSK transmission, the oscillator frequency can be detuned by a
fixed amount by switching an external capacitor via FSKOUT (pin 11).
The condition of the switch is controlled by the signal at FSKDTA (pin 7).
Table 2-5
FSKDTA (pin7)
Low¹⁾
Open²⁾, High³⁾
1) Low: Voltage at pin < 0.5 V
2) Open: Pin open
3) High: Voltage at pin > 1.5 V
FSK Switch
CLOSED
OPEN
2.4.3 Power Amplifier
In case of operation in the 868-870 MHz band, the power amplifier is fed directly
from the voltage controlled oscillator. In case of operation in the 433-435 MHz
band, the VCO frequency is divided by 2. This is controlled by FSEL (pin 15) as
described in the table below.
Table 2-6
FSEL (pin 15)
Low¹⁾
Open²⁾
1) Low: Voltage at pin < 0.5 V
2) Open: Pin open
Radiated Frequency Band
433 MHz
868 MHz
The Power Amplifier can be switched on and off
by the signal at ASKDTA (pin 6).
Table 2-7
ASKDTA (pin 6)
Low¹⁾
Open²⁾, High³⁾
1) Low: Voltage at pin < 0.5 V
2) Open: Pin open
3) High: Voltage at pin > 1.5 V
Power Amplifier
OFF
ON
The Power Amplifier has an Open Collector output at PAOUT (pin 14) and
requires an external pull-up coil to provide bias. The coil is part of the tuning and
matching LC circuitry to get best performance with the external loop antenna.
To achieve the best power amplifier efficiency, the high frequency voltage swing
at PAOUT (pin 14) should be twice the supply voltage.
The power amplifier has its own ground pin PAGND (pin 13) in order to reduce
the amount of coupling to the other circuits.
Wireless Components
2-9
Data Sheet, December 2008