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ADS1232REF: REF board mail function after battery power down

Part Number: ADS1232REF

I ordered a ADS1232REF-Modul to evaluate different bridge circuits. 

At first the module was working fine when I powered it with a 9V Battery. I used a weak battery and it became empty very quick, so the module turned off. Now after replacing the empty battery with a new one the module does not power up. I checked the battery power to make sure its at 9V, also I tried an external power supply at 9V. 

At all test points on the module ( Vref+, 5V, 3.3V) I only measure 0.2V against GND.  

Is it possible to get an replacement for the board or is this a known error? 

  • Hi Florian,

    It is uncommon to have supply issues with this board as it was initially factory tested and programmed.  Also, you said it was initially working.  I would recommend the following:

    Double check and make sure a few settings are in the correct position.  First of all check and make sure that the SW9 device programming switch setting is in the JTAG position and not the USB.  You cannot power the board via USB and if the switch is in the USB position, the power becomes disconnected at various points within the board.

    Also make sure that the ground is making good contact at J2.  If the wrong sized barrel jack was placed into J2, the spring ground connection can sometimes open the ground connection.  This can be verified with an Ohmmeter.

    Also, the diode D1 can be damaged if the supply was connected incorrectly.  If the supply was reverse connected then it is possible that diode could have been damaged by too much forward current through the diode.

    It is possible that you are shorting the supply if the excitation is incorrectly wired at the terminal block.  I would suggest disconnecting any connections that you make connected to either the terminal block J4 or the header J6.  If the supply is shorted the LDOs will shut down due to thermal overload and no longer provide current.

    Best regards,

    Bob B

  • Hi Bob, 

    thanks for the fast help. 
    I double checked everything but I can't get the board running again: 

    • SW9 device programming switch setting is in the JTAG position
    • I disconnected any connections on J4 or the header J6
    • I tried 9V battery supply and 2.5mm Power Jack with 9V (out = GND, in = 9V, like  tip positive/sleeve negative)
      • Spring jack is therefor not a problem 
    • I used a Battery so revers current cant be the problem, I payed attention to plug it correctly 

    After all I tried to apply 5V directly to the 5V Pint with a laboratory power supply, to see if the DC/DC converter is damaged. But the board does not power up either!

    Is there anything more I can try or is it possible to get the board replaced?

    Best greetings 


    Florian Mayerle 

  • Hi Florian,

    Did you happen to check D1 to make sure that this diode is not shorted?

    Can you tell me in detail how you applied the 5V/GND to the board?  Attaching a picture of how this was done would be helpful.  My concern here is not knowing what caused a working board to fail.  Also, can you tell me what and how the external sensor was connected to the board when it failed?  It doesn't make sense to me that just replacing the 9V battery could damage or prevent the board from working.  I am concerned that this could happen again.

    Best regards,

    Bob B

  • Hi Bob, 

    I can measure 9V on the D1 Diode Input, therefor I assume it is not shorted. 

    I applied 5V directly to the 5V Test Port ( TP3) and GND to common grounding of the Board. I only did this after nothing was working anyway, so I would not try this on a proper working board. 

    Here a picture how I wired the sensor (Honeywell 26PC series) .
    Connection of Sensor Honeywell 26PC

    Best regards 
    Florian 

  • Hi Florian,

    I appreciate your patience and if you could check a couple more things I would appreciate it.  I want to double check that there is not a board design or manufacturing issue that may impact other customers. 

    The test point connection you made is at the output of the regulator U1.  It would be helpful for me to know if switching to the USB mode position on SW9 makes a difference.

    1. Switch SW9 to USB mode.
    2. Plug in the 9V battery.
    3. Check TP3 to see if 5V is available or still only 0.2V.

    If TP3 is 5V, then we know there is an issue much deeper along the analog supply path.  If TP 3 is still at 0.2 V, this would mean that the there is something wrong with the regulator or regulator output capacitor C19. Another test that would help confirm the issue is to:

    1. Remove the 9V battery.
    2. Keep SW9 in USB mode.
    3. Plug in the USB cable to the ADS1232REF.
    4. Verify that TP4 is 3.3V and J6 EXC+ is approximately 5V.

    I also realized that there could be some confusion as to the J6 header pin numbering with respect to the schematic.  The pin numbering is reversed in the schematic as compared to the ADS1232REF user's guide connection diagrams.  Always use the silkscreen labeling on the PCB as there is no clear indication which end of the header is pin 1 versus pin 6.

    Regarding board replacement, is it ok if I contact you directly using the email address you provided from your E2E account?

    Thanks,

    Bob B

  • Hi Bill, 

    its also important for me to know where the problem is, because I want to use the board or IC's in some designs. 

    • If I switch SW9 to USB mode and then plug in the 9V battery I can measure 1.0V on TP3.
    • If I remove the 9V battery and keep SW9 in USB mode, then plug in the USB cable, then I can measure TP4 is 3.3V and J6 EXC+ is  5V.
    • I used silkscreen labelling on the REF-board at J6 

    Yes you can contact me regarding the replacement via this mail address:  florian.mayerle@ipa.fraunhofer.de

    Best Regards 

    Florian Mayerle

  • Hi Florian,

    Thanks for the troubleshooting.  Based on the information you have given me, most likely one of two components has become damaged as indicated in the image below.

    Based on the information given I think that U1 is the most likely to have been damaged.  The TPS76350 is a 5V, 150mA LDO regulator that has an absolute  maximum input voltage of 10V.  The ADS1232REF board has been out over 15 years and I have not seen an issue with this regulator in the past.   In most use cases the most common battery is the 9V alkaline type.  I suppose that Lithium or a rechargeable battery may have an output voltage that can exceed 10V when new or just fully charged.  This is the most likely scenario based on the 'older' battery was working and a 'new' battery created the issue.

    So be careful in that 9V is the nominal voltage for the battery, but using a 'new' battery may have greater than 9V output initially.  If greater than 10V is applied to the TPS76350 then the device will be damaged.  I didn't design the ADS1232REF, but at the time there were limited power management devices that had low-noise output available.  In a future design it would make more sense to use a device with a wider input voltage range.  For example, LP2992IM5-5.0/NOPB that has a maximum input voltage of 16V and has lower noise than the TPS76350.

    Best regards,

    Bob B

  • Hi Bob, 

    i tested the first battery when I used it at first, it had around 7V to 8V. And the new battery was at 9V when I used it, so it should not caused the damage. 
    Anyway, I might try to get a replacement for the cap and the regulator to see if it works. 

    Thanks for your excellent support so far. 

    Best regards 
    Florian Mayerle