TH71072EDC

TH71072EDC Datasheet

TH71072

Part	Datasheet
TH71072EDC	TH71072EDC (pdf)

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TH71072 315/433MHz ASK Transmitter / LO Source ! Fully integrated, PLL-stabilized VCO ! Flexible frequency range from 310 MHz to 450 MHz ! ASK achieved by on/off keying of internal power amplifier ! FM possible with external varactor ! Wide power supply range from V to V ! High over-all frequency accuracy ! Very low standby current ! Adjustable output power range from -15 dBm to -1 dBm ! Adjustable current consumption from mA to mA ! Single-ended RF output ! Clock output for µC drive ! Conforms to EN 300 220 and similar standard Ordering Information Part No. TH71072 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 RO 2 ENTX 3 CKOUT 4 TH71072 8 VEE 7 OUT 6 VCC 5 PS/DATA Page 1 of 10 Data Sheet Dec. 2001 TH71072 315/433MHz ASK Transmitter / LO Source The TH71072 ASK transmitter IC is designed for applications in the European 433MHz industrialscientific-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 310 MHz to 450 MHz e.g. for applications in the US 315MHz 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 310 MHz to 450 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 TH71072 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 of the PLL and suppresses reference spurious signals. The VCO’s output signal feeds the power amplifier PA . RF signal power Po can be adjusted in six steps from Po = dBm to -1 dBm, either by changing the value of resistor R1 or by varying the voltage VPS at pin PS/DATA. The open-collector output OUT can be used to either drive a loop antenna or to feed a single-ended load impedance. This could be, for example λ /4 monopol antenna or a output port. In any case, an impedance matching network should be added in order to achieve maximum available RF power. Bandgap biasing ensures stable operation of the IC at a power supply range of V to V. Clock Output The TH71072 feature a clock output CKOUT that can be used to drive a µC. The frequency at CKOUT is fref/4. The clock output is slew-rate limited in order to keep spurious signal emission as low as possible. The voltage swing at CKOUT depends on the capacitive loading at this pin. It is approximate 2 Vpp at Cload = 5 pF ASK Modulation The TH71072 can be ASK-modulated by applying data directly at pin PS. This turns the PA on and off and therefore leads to an ASK signal at the output. LO Source Many applications require a stable RF source. For this purpose, the TH71072 can be used without modulation as an easy-to-use, PLL-stabilized, continuous wave CW generator. Frequency Modulation FM For FM operation an external varactor is required. It simply acts as a pulling capacitor connected in series to the crystal. Then the analog modulation signal, applied through a series resistor, directly modulates the XOSC. 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 0 TX disabled whole circuit in standby 1 TX enable TX active Table 1 Modes of operation Page 2 of 10 Data Sheet Dec. 2001 Block Diagram TH71072 315/433MHz ASK Transmitter / LO Source ENTX 3 PA OUT 7 mode control PS/DATA 5 8 VEE charge pump

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TH71072
315/433MHz ASK Transmitter / LO Source
! Fully integrated, PLL-stabilized VCO ! Flexible frequency range from 310 MHz to 450 MHz ! ASK achieved by on/off keying of internal
power amplifier ! FM possible with external varactor ! Wide power supply range from V to V ! High over-all frequency accuracy ! Very low standby current
! Adjustable output power range from
-15 dBm to -1 dBm ! Adjustable current consumption from
mA to mA ! Single-ended RF output ! Clock output for µC drive ! Conforms to EN 300 220 and similar
standard
Ordering Information Part No.

TH71072

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 RO 2 ENTX 3 CKOUT 4

TH71072
8 VEE 7 OUT 6 VCC 5 PS/DATA

Page 1 of 10

Data Sheet Dec. 2001

TH71072
315/433MHz ASK Transmitter / LO Source

The TH71072 ASK transmitter IC is designed for applications in the European 433MHz industrialscientific-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 310 MHz to 450 MHz e.g. for applications in the US 315MHz 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 310 MHz to 450 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 TH71072 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 of the PLL and suppresses reference spurious signals. The VCO’s output signal feeds the power amplifier PA . RF signal power Po can be adjusted in six steps from Po = dBm to -1 dBm, either by changing the value of resistor R1 or by varying the voltage VPS at pin PS/DATA. The open-collector output OUT can be used to either drive a loop antenna or to feed a single-ended load impedance.

This could be, for example λ /4 monopol antenna
or a output port. In any case, an impedance matching network should be added in order to achieve maximum available RF power. Bandgap biasing ensures stable operation of the IC at a power supply range of V to V.

Clock Output The TH71072 feature a clock output CKOUT that can be used to drive a µC. The frequency at CKOUT is fref/4. The clock output is slew-rate limited in order to keep spurious signal emission as low as possible. The voltage swing at CKOUT depends on the capacitive loading at this pin. It is approximate 2 Vpp at Cload = 5 pF

ASK Modulation The TH71072 can be ASK-modulated by applying data directly at pin PS. This turns the PA on and off and therefore leads to an ASK signal at the output.

LO Source Many applications require a stable RF source. For this purpose, the TH71072 can be used without modulation as an easy-to-use, PLL-stabilized, continuous wave CW generator.

Frequency Modulation FM For FM operation an external varactor is required. It simply acts as a pulling capacitor connected in series to the crystal. Then the analog modulation signal, applied through a series resistor, directly modulates the XOSC.

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
0 TX disabled whole circuit in standby
1 TX enable TX active

Table 1 Modes of operation

Page 2 of 10

Data Sheet Dec. 2001

Block Diagram

TH71072
315/433MHz ASK Transmitter / LO Source

ENTX 3

PA OUT 7
mode control

PS/DATA 5
8 VEE
charge pump

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Datasheet ID: TH71072EDC 647809