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TH71221
Transceiver - 27 to 930MHz, FSK/FM/ASK, Multi-Channel
 Download TH71221 Datasheet (PDF)
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TH71221 General Description
The TH71221 is a single chip FSK/FM/ASK transceiver IC. It is designed to operate in low-power multi-channel programmable or single-channel stand-alone, half-duplex data transmission systems. It can be used for applications in automotive, industrial-scientific-medical (ISM), short range devices (SRD) or similar applications operating in the frequency range of 300MHz to 930MHz. In programmable user mode, the transceiver can operate down to 27MHz by employing an external VCO varactor diode.
TH71221 Features and Benefits
- Single chip solution with only a few external components
- Stand-alone fixed-frequency user mode
- Programmable multi-channel user mode
- Low current consumption in active mode and very low standby current
- PLL-stabilized RF VCO (LO) with internal varactor diode
- Lock detect output in programmable user mode
- On-chip AFC option for extended input frequency acceptance range
- 3wire bus serial control interface
- FSK/ASK modulation selection
- FSK for digital data and FM for analog signal reception
- RSSI allows signal strength indication and ASK reception
- Peak detector for ASK detection
- Switchable LNA gain for improved dynamic range
- Automatic PA turn-on after PLL lock
- ASK modulation achieved by PA on/off keying
- 32-pin Quad Flat No-Lead (32L QFN 5x5 Quad)
TH71221 Tools
| Software & Tools |
File Type |
Size |
Revision |
Date |
Action |
| SW7122x |
EXE |
1.5 MB |
x |
8/28/2012 |
|
TH71221 Environmental Information
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TH71221 Frequently asked Questions
TH7122 vs. TH71221
Question
Whatt's the main differences between TH7122 and TH71221? The databooks of the parts look very similar!
Answer
it's the same chip inside, the only difference is the package
TH7122 - LQFP32 (for "normal" use)
TH71221 - MLPQ32 5x5 (for small form factor apps)
UART & TH7122
Answer
The TH7122 can receive/transmit serial data. It does not perform any manipulation of the data. The only restriction is the maximum data rate. For data rates up to 20kbps, you can use the "normal" FSK modulation approach by switching the crystal (as shown in the data sheet). For data rates in excess of 20kbps and up to about 115kbps, you should use direct VCO modulation. This is explained in more detail in the application note: "TH7122 and TH71221 High Speed Communication". The note is (like many other app notes) available on the Melexis web site.
please note, UART as a protocol is just a serial communications protocol. The hardware associated to it is the "Universal Asynchronous Receiver/Transmitter (UART) controller". Of course the controller is not part of the TH7122, it's the hardware in your PC, MCU or what ever you use for data processing.
NRZ Voltage
Answer
I really recommend to have a closer look at the TH7122 data sheet and the brand new TH7122/TH71221 Cookbook. There you will find the answers of most questions and much more info.
+6/-6V would probably destroy the chip. It must be a positive voltage max. at 5.5V and min. at 0V. Again, please spend a few minutes to consult the data sheets etc!
TH7122 size
Answer
Why do you need to know the chip size? If you want the device with a smaller form factor, you can us the TH71221. It contains the same chip inside but the package is an MLPQ (QFN) with only 5mm x 5mm.
Can you tell us a bit more about your application? What's the projected volume?
TH7122EVB Antenna
Question
Where can I find some information of the exact impedance of the RF out and RF in of the TH71221 ic? I want to design the matching network exactly to a certain antenna.
Can you pls tell me where I can find information about the quarter wave antenna, focussing on the impedance of the antenna not using a perfect ground plane.
I forgot to tell you, but the tranceiver will work at 400MHz.
TH7122 operation frequency
Answer
The tuning ratio (fmax/fmin) of the VCO is approx. 1.135 at VCC=3V and 1.19 at VCC=5V. Using an additional hyper-abrupt varactor diode this ration can be increased up to 2. In your case the required ratio is 5. It's therefore impossible to operate in that huge frequency range without any change of the external tank circuitry. A Multi Band Switching circuit is explained in the TH7122 and TH71221 Cookbook http://www.melexis.com/relinfofiles/AN7122x-Cookbook_rev-003.pdf
TH71221 FM transmitter
Question
I am designing a narrow-band FM transmitter with the TH71221 in the frequency range (150-174)MHz. I am using direct VCO modulation, and a rebuild evaluation board works fine. In order to make the PCB as small as possible, I intend to use a (3.2 x 2.5)mm TCXO for external reference frequency. Can I go a little higher than 16MHz stated in the datasheet, say 16.625MHz? During power on the microprocessor keep the TH71221 in ASK receive mode and a 10 MHz ASK signal from a remote control transmitter is coupled wireless to the IF input (pin1). The demodulated datastream from pin 8 is feed to the microprocessor for setting up the frequency and the power level and switching to TX-mode. To be able to reprogram the transmitter, we have to switch the TX off and on once more. It would have been very nice, if the IF- and ASK demodulator sections could have been kept alive during transmit-mode. Is this in any way possible?
TH711xx family
Question
Although the TH711xx family specs indicate 315Mhz and above, will they work reliably at 216Mhz?
I need bare bones FM audio, RX only, at 216-217Mhz. Is the TH71221 my only option?
TH71221 problem!
Question
We are using Th71221 as FSK transceiever.
Frequence138.350-138.850Mhz.
We designed Pcb according to the datasheet.But there are problems in debugging.First work in tx mode.When write data to register,input any datas,the output frequences around 250-290MHz,and can not detect the PFD,the 8MHz reference oscillator state is normal.Then we cancelled the varactor diode,work in Stand-alone use mode,the output is the same result.Please show me where the wrong happens by any possibility.
TH7122 or TH71221 at 151MHz
Question
I wish to make a 151-152mHz system using either a TH7122 or a TH71221. I want to be able to switch the frequencies within this band when necessary. I also want to vary the power levels. It seems this can be done when in the 300-930MHz band but I cannot see if this is possible in the extended frequency bands. Can someone please advise.
How to use TH7122 at 27.505 MHz 4Watts
Question
I’m developing an RF network for irrigation control at licensed freq. 27.505 MHz (FM), An order to upgrade and simplify the electronic circuits I am thinking the possibility of work with the IC TH7122 or TH71221.
Is it possible to work with TH7122 at 27.505 MHz? What is crystal value an the registers values of the TH7122? Is possible to amplify the output to 4 W ?
Help with TH71221
Question
I am using TH71221 in both high speed and extended frequency applications. According to the cookbook, it needs an external varactor and direct VCO modulation. And this design is quite the same with the Narrow Band application which is only suitable for low speed applications. Is this a problem I have to solve and how?
Question
As part of bigger project i need to design FSK transciever (for short (only few bites at a time) sporadically send packets of data) at 86,79 MHz, and TH71221 is probably the best solution. But i'm little inexperienced in this area. Can be found (somewhere) some sort of ste-by-step guide for design this sort of circuit??
Answer
you may use the TH71221 (or TH7122) but it requires a 10.7MHz crystal IF filter if a 18kHz BW is needed. The smallest BW 10.7MHz ceramic filters have about 30kHz (e.g. Murata). So this could make the circuit a bit expensive. Make sure the PA is well isolated from the IC (small S12). Otherwise the 2W booster can load pull the VCO and kick off its frequency.
The receiver TH71102 could be used at 455kHz IF where you can use a cheaper narrow-band ceramic filter. But with this IC you would have to switch the reference xtals to achieve your two RFs. The same for the transmitter, of course.
Answer
Both devices TH7122 and TH71221 are available.
You should contact the Melexis representive in Australia to ask for samples and for a volume quote. This is the company called Alliance. Contact is Dick Naylor at: d_naylor@bigpond.com
What volumes are you talking about?
Question
[QUOTE=karl] Both devices TH7122 and TH71221 are available.
You should contact the Melexis representive in Australia to ask for samples and for a volume quote. This is the company called Alliance. Contact is Dick Naylor at: d_naylor@bigpond.com
What volumes are you talking about?
Regards
Karl
[/QUOTE]
Only the 1-9 at present. Will contact Oz Agent.
Question
QUOTE=karl] Both devices TH7122 and TH71221 are available.
You should contact the Melexis representive in Australia to ask for samples and for a volume quote. This is the company called Alliance. Contact is Dick Naylor at: d_naylor@bigpond.com
Regards
Karl
[/QUOTE]
Did this and this is the reply:
The cost to send just 1 sample by courier direct from Melexis is more than the total price I quoted you for 10pcs and I understand your total project number is just 10~ 25pcs which is generally not a large enough project volume for any semiconductor manufacturer to provide free of charge samples , please provide the following project details and I will consider sending a sample to you.
(NBB I have 6 samples of SAW 465MHz from JRC in-hand???)
Answer
you may use the TH71221 (or TH7122) but it requires a 10.7MHz crystal IF filter if a 18kHz BW is needed. The smallest BW 10.7MHz ceramic filters have about 30kHz (e.g. Murata). So this could make the circuit a bit expensive. Make sure the PA is well isolated from the IC (small S12). Otherwise the 2W booster can load pull the VCO and kick off its frequency.
The receiver TH71102 could be used at 455kHz IF where you can use a cheaper narrow-band ceramic filter. But with this IC you would have to switch the reference xtals to achieve your two RFs. The same for the transmitter, of course.
Karl[/QUOTE]
Thanks for info, Karl. Intention would be to use 2 chips in the Controller (TX + RX) and switch TX/RX at nodes.
Just printed data to study.
RFID 915 Mhz
Answer
thank you for you inquiry. We are just about to develop a 860 to 960MHz reader. The plan is to have first engineering samples in Q4-09. Here are some general features of the IC:
Full-duplex transceiver
Highly linear RF input
Fully integrated PLL-based synthesizer
Quadrature direct down-conversion architecture
Digital channel filtering and base-band processing
Low shut-down current consumption
Wide operating temperature range
Highly sensitive Listen mode
ASK or PR-ASK modulated RF carrier for Reader-to-Tag communication
On-chip power amplifier
High over-all frequency accuracy
32-pin package 32L QFN7x7
You can check the TH71221 RF transceiver data sheet. It could be used as an analog front-end. Of course, this 27 - 930MHz transceiver wasn't optimized for use in UHF RFID.
EVB7122
Answer
You can use the TH7122 or TH71221 with an external narrow band IF as a dual conversion receiver. Modulation is done by directly modulating the VCO.
TH7122
Question
I saw in the Application Note "TH7122 and TH71221 High Speed Data Communication" that the transceiver could be used at a data rate of 115kb/s, and not only the 40kb/s indicated in the datasheet.
Could this data rate be obtained in ASK modulation ? because explanations are only given for a FSK use.
Question
I saw in the Application Note "TH7122 and TH71221 High Speed Data Communication" that the transceiver could be used at a data rate of 115kb/s, and not only the 40kb/s indicated in the datasheet.
Could this data rate be obtained in ASK modulation ? because explanations are only given for a FSK use.
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