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EVB7122
Evaluation Board for TH7122 and TH71221
 Download EVB7122 Datasheet (PDF)
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EVB7122 General Description
The TH7122 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 300 MHz to 930 MHz. In programmable user mode, the transceiver can operate down to 27 MHz by employing an external VCO varactor diode.
EVB7122 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 for extended input frequency acceptance range
- FSK for digital data or FM for analog signal reception
- FSK/ASK mode selection
- RSSI output for 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
- 3wire bus serial control interface
- EVB comes with a cable to connect to a PC’s LPT port
- EVB programming software is available on Melexis web site
EVB7122 Tools
| Software & Tools |
File Type |
Size |
Revision |
Date |
Action |
| SW7122 |
EXE |
3.3 MB |
4.08 |
3/13/2006 |
|
EVB7122 Environmental Information
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EVB7122 Frequently asked Questions
TH7122 Calculations
Answer
I need to redesign the TH7122 for 418 Mhz at 0 dBm. I am trying to understand your example EVB7122 for 433.92Mhz. LTX0 is j41 and CTX4 (6.8pF + 3 pF) is -j38. You calculate RL as 260. Where does RL come in? Is this what the PI network is looking at? Are you matching 50 ohms on the antenna to 260 ohms of the PA? I am running 3.6V at 0 dBm which gives me 4.2K. Is this what I should match to?
Answer
The PA load is about 260 Ohms and the PI network matches it to 50 Ohms. Attached is a schematic for you.47E_EVB7122B-418-FSK.pdf
TH7122EVB Antenna
Answer
1) The EVB7122 contains a 50ohm SMA connector for RF in/output which can be used for a lambda/4 monopole antenna. This antenna is more efficient than a PCB loop antenna. A distance of 350m line-of-sight should be achievable, but it depends on several environmental conditions.
2) It should be ensured that the TX center frequency is equal to the RX center frequency. Of course also RX and TX should operate on the modulation scheme. Pls. also check the output power of the TH72011 in comparison to the MC33593. If the TH72011 antenna network is properly tuned there should be an improvement of approx. 3dB in comparison to the MC33593.
It is also important that the data rate selection bits (DR0,DR1) of the MC33593 are set according to the TX data rate. I don't know if it's necessary to send a kind of sync word to the RX in order to start-up data decoding - this should be checked by your side.
TH7122 Antenna
Question
I want to apply your EVB7122-433-FSK in 200 meters.pls help me to provide a helical antenna parameter,I need the antenna is 3.5Cm length.For example,the length,diameter,Screw-pitch.
TH7122 and EVB7122
Question
I buy th7122 and evb7122
I have a question about "FSK Application Circuit"
In TH7122 rev003 datasheet and EVB7122 re002 datasheet,th pin32(OUT_MIX) of IC is connect throught CERFIL to Vcc.
But in TH7122 rev004(new release) the pin32(OUT_MIX) is connect throught CERFIL to ground.This is a lot different
Please give me a answer
Source for the EVB7122X-433-FSK-C?
Question
Can you tell me where I can buy the EVB7122X-433-FSK-C evaluation board? I have not been able to locate it from distributors or the online store here.
TH7122 and EVB7122 ?
Question
When are the EVB7122 boards going to be available and is there an approximate price for the eval board ? Also are there going to be any more in depth app notes on using the 7122 in analog voice applications in the near future ?
Mike
Answer
EVB7122s are available for a long time. The price for a standard EVB7122 is USD198 per unit (incl. PC cable).
The TH7122x Cookbook (avail. on our web site) also deals with analog modulation (sec. 3.7) and demodulation (sec. 5.7). It shows you how to use the TH7122x for analog FM, the rest of the circuit, like a microphone amp or an audio PA, is up to you.
TH7122 high side injection
Answer
Would you like a schematic for the EVB7122-special-915-ASK? It is important to use a PLL comparison frequency of 500kHz or above. Please contact an application engineer through your local sales representative.
EVB7122 in FRS band
Question
We are designing a audio/voice device FRS compatible. For prototyping, Can we just set EVB7122 board to work in 462Mhz (FRS) band? Or, must we have to replace some components to put it to work on that band?
Answer
The EVB7122 for 434MHz can be used for 462MHz. You only need to decrease the tank inductor L0 so that it can operate at the intended frequency. To tune the L0 inductor the voltage level at pin LF (loop filter) must be virtually centered around VCC/2 for both RX and TX mode ((VLF_RX + VLF_TX) / 2 ~ VCC/2). In any case the VLF should not exceed VCC-0.3 or below 0.3V for correct operation of the PLL (PFD/CP).
TH7122_Trasmitter circuit_915MHz
Answer
The EVB7122 data sheet on our website has schematics, pcb layout and component lists. The Gerber files for the board are also available.
debugging of TH7122
Question
I am having a problem when debugging the transceiver. My design is completed acording to EVB7122-special-27-FSK-WB-low side LO. A 8MHz oscillator is applied at pin 10(RO), then pin pin19(lock detector output) must output a high-voltage after PLL locks. I cannot detect such a high voltage. why? Please help????
Another question, how will I know the control words are successfully programmed into the transceiver?
EBV71221
Question
I have just modified two EBV71221 (FSK - 315 MHz) evaluation board to work at 27.505 MHz narrow band
The component values where from the document “EVB7122-special-27-FSK-NB-low side LO.pdf”,
I left de original CERDIP and IFFIL
and the XTAL that is set to 4.000 MHz to get ftx=27.505MHz and flo=38.205 MHz
To make the board working I have to change the value of LO from 3.3uH to 1.2uH and program the board at high side injection
The problem I have is that the board doesn’t receive if the power supply is below 3.7 V
And how to calculate the value of the components of the board for better performance at 27.505 MHz and a bandwith of 3KHz
(CERDISC, CERFIL, RLO,CPO,LIF1,CIF1,LO,LRX,LTX,….)
EVB7122
Question
How does the EVB7122 evaluation board work if the modulation is FSK?
Question
The EVB7122 comes in several different variants, depending on which frequency you want. Are these freq's fixed, or can I still use any freq between 300 and 915MHz with these evaluation boards?
Question
I have to design a transceiver at 170MHz. I got a EVB7122 board and put on the VCO an external varactor diode (BBY53) to get this output frequency.
When I try to increase the TXPOWER from P1 to P2 the voltage on Pin 23 (LF) is going to zero and so the output frequency change. Then I changed the VCOCUR to the highest. After that it works. But then I changed from P2 to P3 and I have the same problem.
Can you please help me what is to do that the Output frequency is constant at every TXPOWER mode?
Question
I am unable to change the transmit frequency of the evb7122 eval board with the melexis software. I'm using 5 volt VCC and my parallel port output high level is 5v. A logic analyser on the sclk, sdata, adn sden lines show valid timing.
Question
We are developing a audio/voice device, FRS compatible. For prototyping, can we just configure the EVB7122 to work in 462Mhz(FRS)band? Or, Should we have to replace some components of EVB7122 board?
Question
We purchased 3 EVB7122 evaluation boards. We have attempted to run them in the stand-alone user mode of operation. None of the boards run at the 915 MHz for which they were jumpered. We are running the boards at 5V. Any feedback would be appreciated.
TH7122
Answer
Thx for reply to Pll port program. At this point it's just as easy to use the W98se system. I'll look closer when time permits.
But even now, the RO is fine at 7.1mhz but when I load with the Melexis EVB7122-SPECIAL-37-45-FSK-WB settings, it seems that in TX node the RF frequency is >400Mhz. I expect to see an offet to the frequencies due to the fact that these settings are for 8.0Mhz and 3.6V, while with the Eval board we are at 7.1mhz and 5.0V.
We have not been able to affect this TX frequency no matter what we do. Tried different eval board, same results. No matter what programmed, RF freq at coax at <400mhz.
Dos anyone have an answer why the Tx freq will not change?
Question
I need to transmit at 600MHz in programmable user mode-FSK application circuit, because no 600MHz at TH7122 datasheet FSK test circuit component list.
1. Is there a way to calculate all the external components for this freqency? ( example:impedance matching inductor,tank inductor,matching network etc.)
2.I am use TH7122, no use EVB7122
Question
I need to transmit an analog signal(PWM from a uP)(490Hz) on 187,5MHz with a th7122.
I have a schematic of: EVB7122B-218-219-NB-FSK.UTSCH - EVB7122.
I was told to just increase C13 and C9. Would C13=18pF instead of 15 pF, and C9=10pF instead of 6 pF do? Or do i need to go higher?
Now i have read the cookbook. It says that i need an extra varator and a sallen key filter at RO and DEM_out to make an FM-transmitter?
Could you help me with the right design please?
TH7122 - External VCO design/FSK
Question
I designed a board based on the external vco as shown in the document EVB7122-special-37-45-FSK and cannot seem to get any reaction from the th7122 after programming with the external host.
So far we have confirmed that the SCLK, SDATA and SDEN are all correct, including the bit order MSB->LSB, SDATA stable prior to rising SCLK edge and the SDEN pulse after sending the 24 bit frame.
The only test that I can come up with is to set Receive mode and check for the RO signal. In all cases my target has no RO activity.
With this external VCO control, is the RO test still a valid measure of functionality?
Lock Detect - TH7122
Question
We are using the EVB7122-special-37-45-fsk-wb app note with a single frequency of 45.0Mhz.
CF2 100nF PLL loop filter
CF1 1uF PLL loop filter
RF 1.5k PLL loop filter
The time from transmitter start to LD high is 18 ms. Is that correct for those values in the loop filter? Can the PLL lock time be speed up? If so How much?
On the receive side, we are finding that the first 5 bit times (9600 bps right now) are garbage.
C3 10nf data slicer cap
C4 omitted demodulator filter
How can we reduce that start up delay?
For that design, what is the range of NRZ data rates?
TH7122 PLL problem
Question
Hi
I've been developing successfully with the TH7122 for a number of months now but have just come upon a problem that I can't solve.
Basically I can't seem to setup the device to use certain feedback divider numbers (NT). Specifically the ranges:
N=85 to N=95 (using RT = 31)
N=187 to N=191 (using RT = 62 or RT = 55)
Use of any of these numbers results in the PLL generating the frequency at the bottom of the above range. Ie. NT=91 generates the same frequency as for NT=84 (Though N=83 and N=96 both generate the correct frequency)
I have this problem using my own circuit, as well as the “EVB7122 Special” board + the LPT setup software, and just can’t seem to find a solution. I was wondering if anyone else had this problem at all? Or if someone can suggest what I might be doing wrong?
Discriminator filter for TH7122
Answer
OK, I think I fixed my problem. I replaced the resistor on the EVB7122 board across the discriminator with a 2-10pF variable cap. I also replaced the original discriminator with the CDSCB10M7GA135 for testing. I was able to get a demod signal by adjusting the variable cap.
Buy EVB7122
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