Not recommended for new designsTH71081
868/915MHz
ASK Transmitter / LO Source
Features
Fully integrated, PLL-stabilized VCO
Frequency range from 850 MHz to 920 MHz
ASK achieved by on/off keying of internal
power amplifier
FM possible with external varactor
Wide power supply range from 2.2 V to 5.5 V
High over-all frequency accuracy
Very low standby current
Adjustable output power range from
-15 dBm to +1 dBm
Adjustable current consumption from
6.2 mA to 12.5 mA
Differential output well-suited for loop antenna
Conforms to EN 300 220 and similar standards
8-pin Small Outline Integrated Circuit (SOIC)
Ordering Information
Part No.
TH71081
Temperature Code
E (-30 C° to 85 °C)
Package Code
DC (SOIC8)
Application Examples
Keyless car and central locking
Low-power telemetry
Alarm and security systems
General digital data transmission
General analog audio signal transmission
Local oscillator signal generation
Pin Description
LF 1
RO 2
ENTX 3
PS/DATA 4
TH71081
8 VEE
7 OUT1
6 OUT2
5 VCC
General Description
The TH71081 ASK transmitter IC is designed for applications in the European 868MHz industrial-scientific-
medical (ISM) band, according to the EN 300 220 telecommunications standard. It can also be used for any
other system with carrier frequencies ranging from 850 MHz to 920 MHz (e.g. for applications in the US
915MHz ISM band).
The transmitter's carrier frequency fc is determined by the frequency of the reference crystal fref that is used.
The integrated PLL synthesizer ensures that each RF value, ranging from 850 MHz to 920 MHz, can be
achieved by using a crystal with reference frequency according to: fref = fc/N, where N = 32 is the PLL feed-
back divider ratio.
3901071081
Rev. 009
Page 1 of 12
Data Sheet
May/05