This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Replacement for TMS37157

Other Parts Discussed in Thread: TMS37157, UCC27424-Q1, RI-TRP-DR2B, TMS3705

In a project I do I have been using a combo of RFID reader IC TMS3701 and passive tag TMS37157 to power MSP430.

I wish to increase the read range to around 20cm. Does anyone know if there is a better solution or next gen product now?

Thx,

Nick

  • Hi Nick,

    20cm will be very difficult. We have the RF430FRL15xH devices, which also include an integrated MSP430. For 20cm range, you will need large antennas and power amplifier. I suggest the Feig LR readers which offer high output power. What are your limitations on antenna size for reader and tag? Also, how much power does the MSP430 require for your application? Based on this, I can tell you if this would be feasible using magnetic field RFID.
  • Hi Eddie:

    Thanks for the reply!

    Tag antenna is 3mm in diameter with ferrite core.

    Reader antenna is around 200-300mm in diameter.

    I am already using the UCC27424-Q1 power amp(similar model) at the reader output.

    The transponder looks very similar to ri-trp-dr2b. 

    I have read a report using RI-RFM-007B-30 to further boost the reader power. However, I am not sure how small i can integrate part of the circuit to make it wearable?

    I am ok with reducing the read distance to 10-15cm, but I need it to have great tolerance to angular misalignment between the two coils.

    To us the main purpose of using TMS37157 and TMS3705 is to have a wireless power solution and a low power communication link so our transponder device does not need battery. I am open to suggestions of using other solutions. 

    thx,

    nick

  • Hi Eddie,

    Have you found out whether if it is possible to use the RF430FRL15xH with my application?

    Thanks,

    Nick

  • Nick,

    How much current do you require on the tag side?  

    The RFM-007B could certainly improve your power output and range, but it is a larger module.  I think this would meet your range requirement depending on how much power the tag side requires.

    If you wanted to consider HF with the RF430FRL15xH, you would also need to have a higher power reader and/or larger tag antenna.  This may be achievable with HF, but really depends on how much power you need on the tag side since the RF field strength will be significantly lower at 15 - 20cm.

  • Hi Eddie:

    The current required on the tag side is 700uA at the peak when ADC is working. around 20uA idle and 300uA active. 

    Our current prototype with TMS37157 works fine, but we wish to improve the tolerance angle when coil misalign. We are charging a 10uF cap to be the power source for the tag. Our system takes measurement every few min, as Ti's Tiris system is sequential Half duplex, communication stage is kind of seperate from power transfer stage, it is ideal for us.

    1. There are few ways to improve the range, but antenna dimension is constrained, thus increasing transmitted power is the most straight forward way. I know RFM-007B can be an option, but I really wish to avoid using it due to its size and weight. Do you have any suggestion on compatible antenna driving circuit bit more powerful than the range extender solution using 15V  UCC27424-Q1 and not as bulky as RFM-007B?

    2. Apart from brute force method of increasing the power,  I have been thinking about using very high Q reader antenna during power transfer stage, then MUX the reader antenna with a damping resistor during communication stage so there is enough bandwidth for the data transmission. Do you think this is feasible?

    3. When the tag is placed just a bit too far away from reader range, does it usually stop working because not enough energy to power on the circuit, or is it because the reflected load modulation seen by the reader antenna is too weak to be detectable thus communication fail?

    Regards,

    Nick

  • 1. No I do not have another suggested circuit for higher power.

    2. I could potentially work to increase the range, but I have never experimented with something like this.  I recommend testing the power transfer of the high Q antenna first before adding the mux.

    3. When we are talking about a simple passive RFID tag, it is usually the reader not being able to detect the load modulated response.  In the case where you are pulling significant current on the tag, the issue could be that the device is not receiving enough power.  You could test this by measuring the voltage on the tag side at range and see if it is within the threshold.