TH71082 Datasheet | Melexis

Features ! Fully integrated, PLL-stabilized VCO ! Flexible frequency range from 800 MHz to 930 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 -18 d Bm to -2 d Bm Adjustable current consumption from 6.2 m A to 12.5 m A Single-ended RF output Clock output for µC drive Conforms to EN 300 220 and similar standard Ordering Information Part No. TH71082 Temperature Range -40 C° to 85 °C Package 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 8 VEE RO 2 ENTX 3 CKOUT 4 7 OUT 6 VCC 5 PS/DATA TH71082 Data Sheet 3901071082 Page 1 of 10 Dec. 2001 Rev. 004 868/915MHz ASK Transmitter / LO Source General Description The TH71082 ASK transmitter IC is designed for applications in the European 868MHz industrialscientific-medical (ISM) band, according to the EN 300 220 telemunications standard. It can also be used for any other system with carrier frequencies ranging from 800 MHz to 930 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 800 MHz to 930 MHz, can be achieved by using a crystal with reference frequency according to: fref = fc/N, where N = 32 is the PLL feedback divider ratio. Theory of Operation General As depicted in Fig.1, the TH71082 transmitter consists of a fully integrated voltage-controlled oscillator (VCO), a divide-by-32 divider (div32), a phase-frequency detector (PFD) and a charge pump. An external loop filter at pin LF determines the dynamic behaviour...