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EVB90121
MLX90121 Evaluation Board
 Download EVB90121 Datasheet (PDF)
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EVB90121 General Description
The EVB90121 is an assembled module that allows to evaluate the advantages of the MLX90121 13MHz transceiver IC and to facilitate the development of RFID applications.
The board voltage is supplied by a jack connector from 6 to 9 Volts DC. The internal power supply of the board can be chosen between 3 Volts and 5 Volts DC by putting the corresponding jumper up or down. A suppression choke reduces the supply noise.
The matching network can be adjusted through CV1 capacitor and thus can be optimized to transmit full electromagnetic power up to 200mWatt to a 50-ohm load antenna connected on a SMA connector.
All digital inputs/outputs from the MLX90121 are connected to a standard 10 pins connector. This allows easy connection to a microcontroller.
EVB90121 Features and Benefits
- Output power up to 200miliwatts
- Complies with standard ISO15693 and ISO 14443 protocols
- Programmable encoder for custom protocol
- Short to medium reading range applications
- Matching network optimized for 50 ohm antenna impedance
- 10 pins connector for communication with a microcontroller
- Board voltage supplied by a jack connector from 6 to 9 Volts DC
- Internal power supply of the board between 3 Volts and 5 Volts DC
EVB90121 Environmental Information
This text will be replaced
EVB90121 Frequently asked Questions
MLX90121 antenna circuit example needed
Answer
You are correct. What Melexis provides are only examples of antenna and matching networks. It is usually sufficient for our customers to start with.
My advise is for you to purchase the EVB90121. the circuitry comes with the documentation. Please contact your nearest MLX distributor.
As far as meeting the FCC or EN requirements, this is application specific and therefore remains under the responsibility of our customers.
Help about MLX90121
Question
i used a external uC to drive the evb90121. the configuration is iso 15693 fsk, 10%modulation as page 23 of MLX90121. i used symbol 1 out of 4 and send a request:
SOF-00001001(sym1-sym2-sym0-sym0)...EOF(lsb first)
wait about 300us
set CK high about 2ms
but no response in dout
Question
i have bought EVB90121, i want to study about it and have severe question:
EVB90121 make Send Request or by microcontroller ?
and if uP make send request, struct of send request?
(for iso 14443A,B; 15693)
EVB90109 & EVB90121 boards
Question
I have just received the EVB90109 & EVB90121 boards. I have installed the UT121 software and it updated itself to this:
Lib Mosaique; Release 1.5 (version: 1.5)
Lib Ut121Ban; Release 2.14 (version: 2.14_0)
Lib Ut121Main; Release 2.22 (version: 2.22)
Lib Ut121Update; Release 2.1 (version: 2.1)
Fw Ut121Firmware; Release 1.9 (version: 1.9, Build SoftDist/Atmel 2005.10.10/2005.10.10)
I am sending the Root->ISO15693->ISO15693 Dual Sub-carrier->Inventory xxxxxxx0 command and I always get this result:
Iso15 07010100 crc slot 16 wait 2 ->
<- OK - Command has been sent
<- TAG NoResp
<- TAG NoResp
<- TAG NoResp
<- TAG NoResp
<- TAG NoResp
<- TAG NoResp
<- TAG NoResp
MLX90121 Reading Configuration Registers
Question
I recently ordered the EVB90121 evaluation board containing the MLX90121 RFID transceiver, and during development and testing, I realized that the MLX90121 datasheet makes no reference toward how one can read the IC's configuration registers. Waveforms show how to write to these registers, but not how to read from them. Is it even possible to read these configuration registers? If so, would it be possible to get sample waveforms showing how to perform these reads. If it is not possible to read from the configuration registers, is there another way to make sure what is being written to the registers is in fact being written properly?
MLX90109 & MLX90121 Choose
Question
I have two questions:
1.Witch one of MLX90109 & MLX90121 I have chouse for about 15 – 20 cm reading distance and minimum current needed by reader working with 3.3 v battery?
I prefer to use external coil antenna 70 - 80mm diameter on both reader and transponder side.
2.
Why in web store in don’t see EVB90109 & EVB90121 , MLX90109, MLX90121?
Question regarding antenna match on EVB90121
Question
We are currently designing antenna for 13.56MHz applications. The PCB antenna, supplied with the EVB90121, has a 0-50pf where the antenna can be tuned to 50ohms. We have noticed that the cirquit can not be tuned to a pure resistive impedance, but 50ohms either primary capacitive or primary inductive impedance. Which tuning of 50ohms gives the best match for the output on the EVB ?
Another question regarding the Q of the antenna. I've calced the Q to about 40 (takeing account for the parralel resistance of 1.8k and the series resistance of the inductor) but you mention that it's surpossed to be around 14 - how is the Q surpossed to be calculated ?
Answer
The matching network of the RFID antenna provided with the DVK90121 is calculated to provide a 50-ohms resistive impedance at 13.56MHz. The 5 to 50pF adjustable capacitor is on the PCB only to fine adjust the variations of the tune capacitors. The antenna will be matched when a clear sinus of 10Vpp will be seen at the output of the EVB90121 (TP: Vant).
The quality factor of the antenna must be calculated using the current flowing though the inductance loop (3dB bandwidth at 13.56MHz). In this case, the calculations take also care about the matching network. The quality factor has been measured in transmission using a network analyzer.
i need source code for DVK90121
Question
i wanted to know how to communicate with EVB90121 from microcontroller.so i need source code for DVK90121.
Question
Actually we have purchased the development kit.The details are as follows
Universal Development board DVKRFID(2002)
Evaluation board EVB90121(1067)
13.56Mhz PCB Antenna ANT1_0(1046).
Response from sample cards in not consistant(mlx90121)
Question
we are working on the Universal Development board DVKRFID and with Evaluation board EVB90121
i am not getting consistent response for any of the sample cards. Is the chip compatible with ATMEL Crypto RF cards.The cards(14443 A/B, 15693) respond once after many consecutive requests(REQA,REQB and Inventory)
pls let me know the reason.
Answer
The DVK90121 provides a set of commands compliant with the standards ISO15693 and ISO14443. The crypto level is not supported by the DVK90121.
The communication with the computer seems to be good as the samples reply once after many consecutive requests.
Please verify the SMA connection.
Do you try to adjust the capacitor CV1? Please be sure that you get the maximum voltage amplitude on ANT (about 10Vpp).
Please insure that the RFID antenna is not close to a metallic object. The metallic environment must be avoided to get maximal performances.
Please try to change the two power supplies with ones from laboratory (7.5V DC). To verify if the power supplies provided with the kit disturb the EVB90121.
EVB90121 - wrong signals on Dout
Question
I´ve got the Evaluation Board for the MLX90121(EVB90121) and use it to send power to my custom-built sensor-tag circuit and to recieve the data. The senor-tag modulates the field by ASK with a subcarrier (423kHz).
I run the EVB in direct reception mode.
Now the problem...
On the Dout line are some "peaks" appearing without having any modulation on the 13,56MHz field. And the sensor-tag is out of range.
The "peaks" are comming more or less periodical.
I´ve tried to shield the antenna. Without any result. Disconnecting the antenna doesn´t show any effect either.
Answer
According to the direct mode used, the gain of the analog chain can be quite high (direct FM mode). Therefore, some spikes will appear on DOUT and you will have to detect the presence of your transponder by detecting its start of frame or equivalent symbol (spikes will never appear during the reception of the transponder's load modulation).
The best way to reduce these spikes is to use the same register’s configuration as for the ISO15693 ASK (please refer to the datasheet page 22). This will configure the device in AM direct mode with a minimum gain of the analog chain.
Another thing can be the noise introduces by the VDD line. Therefore, please try to change the power supply block of the EVB90121 to see if it is better.
EVB90121 documentation
Question
Is there a revision of the datasheet for the EVB90121 in which the connection table for JP2 (Table 2) and the schematic (Figure 1) agree? Which is correct?
Answer
There is indeed a mistake in the documentation of the EVB90121. The table 2 (description of JP2) is incorrect.
We will make the corrections and a new version will be available quickly.
Many thanks for your remark.
Antenna EVB90121
Answer
The impedance of the antenna provided with the EVB90121 should be 50-ohm resistive at 13.56MHz with a quality factor of about 15.
The matching circuit can be adjusted with the timer capacitor C1.
Question
Can I get information about the antenna which is part of the EVB90121? Where can I get it? What is the correct product number?
Answer
The antenna of the EVB90121 is not available as a product. For further assistance, contact your Melaxis sales representative who can arrange applications assistance
MLX90121 TEST_ANA pin
Question
Is there any documentation on the TEST_ANA pin (pin 18) of the MLX90121? Is there any way to use it as an Received Signal Strength Indicator (RSSI)? Couterintuitively, it appears to follow DSYNC during Majority Voiting with ISO15693-Dual Sub-carrier. Note that while pin 18 is "RES3" on the MLX90121 datasheet, it is "TEST_ANA" on the EVB90121 schematic.
DVK90121
Question
i wanted to know how to communicate with EVB90121 from microcontroller.so i need source code for DVK90121. I have purchase DVK90121 yet I still cant figure out how to communicate from my microcontroller to EVB90121
MLX90121
Answer
The antenna we use is the one which comes with our EVB90121. The dimentions are 12 x 12 cm, one turn, Q factor of 14 and adapted on 50 ohm at 13,56MHz.
For further information on antenna design, you can refer to books such as "RFID Handbook".
MLX90121 - output power
Question
I am using a custom made RFID-circuit based on the EVB90121 (resp. the circuit given in the MLX90121-datasheet).
Even though I already replaced the SMD-inductors (too high ohmic resistance; >1 Ohm) I cannot get the ouput power of 250mW.
For testing the ouput I use a 51 Ohm-Resistor directly at the ouput. Tuning the circuit to get a nice sine-wave works very well, but the peak-peak-voltage ist only 7.4 V which means a power of 136mW.
What could be the reason for that?
By the way: Also VK200 and tantalum-caps (with X7R-caps in parallel) in use. Ripple voltage < 500mVpp.
Question
First of all: Coupling was not the problem but a too low quality factor.
I replaced one coil with one directly from the EVB90121 and it worked.
Furthermore it seems that using 4.7uH instead of 5.6uH leads to a better signal.
But one question: I took a look to different distributors and found that in the best case a quality factor of 60 is available.
My first coils should have had a value of 50 but that seemded to be wrong.
Could you tell me who is the producer of the coils (1.2uH, 4.7uH, 5.6uH) in the EVB90121?
Answer
Please find below the Farnell reference for the coils used in our evaluation board EVB90121:
1.2uH : 508561 (Q = 55 @ 7.96MHz)
4.7uH : 608464 (Q = 60 @ 7.96MHz)
5.6uH : 509929 (Q = 60 @ 7.96MHz)
Sourcecode for DVK90121
Question
I have the DVK90121 and EVB90121. Is it possible to get the source code for the Atmel mega128 on the DVK90121?
MLX90121/EVB90121 current consumption
Question
I am using the EVB90121 with a power supply of 3V and measured a current consumption from 0,7mA (power down) to 100mA (transmitter on).
The MLX90121 datasheet specifies values between 0,1µA and 45mA so I am a little bit surprised about the high values I measured. Are they usual?
By the way, I used the antenna, which as included in the board.
Error in EVB90121?
Question
I think I found a quite important "error" in your EVB90121 layout: As I am using a "non"-Standard-antenna (but with Impedance matching to 50 Ohms) I had to use the external envelope detector as described in your Application notes.
But then I found out that the voltage supply at pin VDD is quite noisy because there you use it as a common pin for the output stage, the digital section and the analog receiver section.
I did a few simulations with a "real" X7R-cap. and found out that due to its limited RF-ability a ripple voltage of appr. 50-100mV peak-peak cannot be suppressed in the actual layout.
If no separate decoupling of VDD occurs at the external envelope detector I found out that the ripple at the RX pin causes wrong "1"-signals at the DOUT pin.
I suggest to use the VK200 choke only to decouple the output stage and connect the other supply lines directly to the output of the voltage regulators; maybe separated by their own L-C-combination.
MLX90121 Receive input
Answer
In order to avoid the saturation of the internal diode detector, a peak to peak voltage of maximum 3 volts should be applied on the Rx pin of the MLX90121. This voltage is fine adjusted with a serial resistor between the antenna and the Rx pin. On the Melexis evaluation board EVB90121, this resistor is currently set to 4k7ohm.
Buy EVB90121
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