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TH72015
Transmitter - 433MHz, FSK/ASK (10L QFN 3x3 Dual)
 Download TH72015 Datasheet (PDF)
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TH72015 General Description
The TH72015 FSK/ASK transmitter IC is designed for applications in the European 433 MHz industrial-scientific-medical (ISM) band, according to the EN 300 220 telecommunications standard; but it can also be used in other counties with similar standards, e.g. FCC part 15.231.
The transmitter's carrier frequency fc is determined by the frequency of the reference crystal fref. The integrated PLL synthesizer ensures that carrier frequencies, ranging from 380 MHz to 450 MHz, can be achieved. This is done by using a crystal with a reference frequency according to: fref = fc/N, where N = 32 is the PLL feedback divider ratio.
TH72015 Features and Benefits
- Fully integrated PLL-stabilized VCO
- Frequency range from 380 MHz to 450 MHz
- Single-ended RF output
- FSK through crystal pulling allows modulation from DC to 40 kbit/s
- High FSK deviation possible for wideband data transmission
- ASK achieved by on/off keying of internal power amplifier up to 40 kbit/s
- Wide power supply range from 1.95 V to 5.5 V
- Operating temperature range -40°C to +125°C
- Very low standby current
- Low voltage detector
- High over-all frequency accuracy
- FSK deviation and center frequency independently adjustable
- Adjustable output power range from -11 dBm to +10 dBm
- Adjustable current consumption from 3.4 mA to 10.6 mA
- Conforms to EN 300 220 and similar standards
- 10-pin Quad Flat No-Lead 10L QFN 3x3 (Dual)
TH72015 Environmental Information
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TH72015 Frequently asked Questions
RF/sensor application advice pls
Answer
the smallest size FSK/ASK transmitters are in micro leadframe packages (MLP) measuring only 3mm x 3mm. They are:
TH72005 (290 to 350MHz),
TH72015 (380 to 450MHz),
TH72035 (850 to 930MHz).
We have seen much smaller than 100sqmm PCBs using these TXs together with a low profile SMD crystal, a small MCU etc.
TH72015 - crystal
Question
I started some design with TH72015 and found it pretty - very easy to use.
But now my crystal has some troubles.
How uses TCXO(only one output pin) to substitute for normal crystal?
Answer
of course you can also use an external oscillator like a TXCO. If you go to the TH72015 DS, pages 3 and 4, you will find the schematic of the crystal oscillator. You just have to input the signal to pin 4 (ROI). Make sure the signal is AC-coupled and the level is between 100 and 500mVpp (try a bit until you get the optimum suppression of PLL sidebands).
But what is your problem with the xtal? It should work quite easily. Please have a look at the DS, page 8, where we provide the recommended xtal specs. Many xtal suppliers have those xtals needed for our RFICs on stock. Note that FSK modulation via xtal pulling requires an xtal!
Question
Thank for your reply.
I checked your TH72015 DS, pages 3 and 4, in the schematic of the crystal oscillator - pin 4 is ROI, pin 3 is FSKSW.
When I uses TCXO to substitute for normal crystal, just input the signal to pin 4 (ROI).
How about the pin 3?
Matching PCB Loop antenna to transmitter
Question
Im working with a PCB loop antenna which has an impedance of about 0.1+j50 at 433.92 MHz. I need to match this to the MELEXIS TH72015 transmitter device.
The datasheet does not give a definite impedance to match to, instead an apps note 'PA Output Matching' mentions an equation for an optimum load resistance. The equation is as follows:
Ropt = ((Vcc - Vsat)^2)/2*Pout
In my particular case, operating at 3V, and transmitting at -12dBm the optimum load resistance computes to 16200. Even using Q degrading to broaden the antennas bandwidth im finding it impossible to match anywhere close to this value (using real component values).
Im wondering is there another way to match my antenna to the device? Or is there some mistake in the method i have used?
Answer
The Ropt is important only when you want to get the maximum power without saturating the PA. Since you can adjust the power level with the TH72015, it is sufficient to tune the antenna with CM1, CM2, LM2 and reduce the output power of the TH72015 by adjusting RPS. LM1 is there mainly to prevent radiation at harmonics and does not need to be changed.
Buy TH72015
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