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TH72031
Transmitter - 868/915MHz, FSK (SOIC8)
 Download TH72031 Datasheet (PDF)
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TH72031 General Description
The TH72031 FSK transmitter IC is designed for applications in the European 868 MHz 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 930 MHz (e.g. for applications in the US 902 to 928 MHz ISM band).
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 850 MHz to 930 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.
TH72031 Features and Benefits
- Fully integrated PLL-stabilized VCO
- Frequency range from 850 MHz to 930 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
- Wide power supply range from 1.95 V to 5.5 V
- Operating temperature range -40°C to +125°C
- Very low standby current
- On-chip low voltage detector
- High over-all frequency accuracy
- FSK deviation and center frequency independently adjustable
- Adjustable output power range from -11 dBm to +9 dBm
- Adjustable current consumption from 5.1 mA to 13.4 mA
- Conforms to EN 300 220 and similar standards
- 8-pin Small Outline Integrated Circuit (SOIC)
TH72031 Environmental Information
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TH72031 Frequently asked Questions
Temperature
Question
My new application is based on the 3rd generation fsk transmitter th72031 specified to work at max 125 degree celcius. what are the design considerations to be counted when the device as well as reference crystal are affected by temperature simultaneously?
EVB72031 Evaluation Board output power
Question
we are currently trying to find a suitable RF transmitter for a RF remote control system. We made good expierence with the Melexis 72031 evaluation board with 50 Ohm connector. But our final design should include a printed loop antenna. The problem is that we have no capability to design one. So we are restricted to copying existing designs.
The description site
http://www.melexis.com/prodmain.asp?search=evb72031&Submit=Site+Search&family=EVB72031
claims 85 dBm output power for this board with loop antenna. Has this actually beeing measured or is this the theoretical output power of the chip? Is this the ideal loop antenna for the TH72031 or could the output power be increaesed by a bigger loop?
Answer
please note the features listed in there: http://www.melexis.com/prodmain.asp?search=evb72031&Submit=Site+Search&family=EVB72031
are just copied from the TH72031 data sheet. It says: "Adjustable output power range from -12 dBm to +8.5 dBm". This is quite difference to 85dBm (which would be a power of 316W!). The 8.5dBm (or 7.1mW) is the conductive power into a 50Ohm load. The effective radiated power (ERP) is about 15dB less, so approx. -30 to -6dBm.
The EVB description must of course be corrected to reflect the ERP values.
TH71081 replacement
Answer
We can suggest following replacements:
TH72031 Transmitter - 868/915MHz, FSK (SOIC8)
TH72032 Transmitter - 868/915MHz, ASK (SOIC8)
TH72035 Transmitter - 868/915MHz, FSK/ASK (10L QFN 3x3 Dual)
For an overview of the main parameters you can download our quick section guide:
http://www.melexis.com/Asset.aspx?nID=3752
For pricing, sampling and purchasing I would like to point you to our local partner in Slovenia:
IC Elektronika d.o.o.
Vodovodna cesta 100
Ljubljana.
1000 Slovenia
Phone +386 1 5680111
Fax +386 1 5689107
E-mail prodaja@ic-elect.si
Web www.ic-elect.si
TH72011
Question
I started some design with TH72011 and found it pretty - easy to be done and with very clean spectrum. But since I'd like to use it in different applications ( mainly alarm systems), I'll need to know the output impedance to mutch the device in the right way. I don't see in the data sheet any information about. Is somewhere data for S22 parameters or/and Smith chart for the output impedance of TH72011?
Next will be TH72031, for it also :)
TH72031 Startup time / ENTX pin
Question
I have an application where I'm upgrading an old sub-assembly module with a TH72031 design that needs to periodically power up and transmit data (868MHz, FSK, 1200baud).
The main constraint is that I only have 3 connection lines available between the main PCB and this module i.e. ground, data and V+.
Is there any reason why I can't tie the ENTX (pin4) permanently to V+, knowing that when I apply power to the IC, it will be ready in transmit mode?
By doing this, my measurements show that the startup time doen not appear to be adversely affected - it is still around 1 msec.
Buy TH72031
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