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.

ADS8698EVM-PDK: ADS8698EVM-PDK related issues

Part Number: ADS8698EVM-PDK

Hello,

Please check our problem. I'd like to ask your advice.

After receiving the product, I tried to connect 5V and 3.3V to the external voltage port J32, J33, respectively. By the way, by applying a 5V voltage to J32 using a DC supplier, it took only 1.8V voltage and became current control mode (No matter what voltage is applied to the 5V port on J32 the current flows to its maximum). It seems that the 5V port on J32 and the ground are shorted to each other.

Also, I would like to ask if there is a way to turn on the product without using the external voltage, J32, J33. As far as I know, J32, J33 seems to be the only way to use it unless we apply voltage to ADC through simple capture card and computer connection. If there is a way to turn on the power without using simple capture card and external voltage port J32, J33, please tell us how.

The reason I bought a new ADS8698-EVM this time is because I applied a high current to the J33 port of the ADS8698-EVM that I was using and the 3.3V port was shorted to ground. Is there a simple way for the user to fix this fault in this case? I have soldering equipment.

If I can't solve this problem, please exchange it for a new. I'll be waiting for your quick reply.

Thank you.

  • Hi July,

    Firstly, when you apply a 5V power to J32 and a 3.3V power to J33, did you connect and use the SDCC to the EVM board? What are the positions for all other jumpers? Where did you see the 1.8V voltage on the board?

     Actually you do not need external 5V and 3.3V power supplies, both supplies on the EVM have been connected to the SDCC (5V_SDCC and 3V3_SDCC) and take the power from the SDCC. The jumper on J13 should be put on pin 2 and 3 position, the jumper on J17 should be used to disable the U9, no jumpers on J12 and J14, the ADC can work without using U4/U5 amplifier and HVDD/HVSS supplies. If you want to use the U4/U5 amplifier, you will have to provide external EXT_HVDD and EXT_HVSS to J18 and use jumpers to connect pin 2 and 3 on the J12 and J14, you can not create HVDD abd HVSS supplies from the 5V supply of SDCC (5V_SDCC) because of current limitation from the USB port.

    Another way to use the EVM is, provide external +5V supply to J32, you can use the 3.3V from the SDCC or provide a +3.3V supply to the J33, however you should remove R78 when you connect the SDCC to the EVM,otherwise the board could be damaged because two supplies are connected together. Make sure all the  jumpers on right positions when you use external power supplies: pin2-3 on J13, a jumper on J17 if U4/U5 are not used. 

    I do not understand your issue/fault, do you mean you made a mistake to connect the 3.3V input on J33 to the ground and apply a high current to J33 (+5V supply?)? then your EVM did not work? please clarify.

    Best regards,

    Dale

  • Hi, Dale

    Thank you for your reply. I'm Yunjae Park. 

    The questioner above asked on behalf of me.

    I wrote down my answer to your question as below.

    - Firstly, when you apply a 5V power to J32 and a 3.3V power to J33, did you connect and use the SDCC to the EVM board? What are the positions for all other jumpers? Where did you see the 1.8V voltage on the board?

    : I haven't used SDCC to apply voltage yet. But I've used SDCC to connect EVM to a computer and measure the voltage using computer software. Can I apply 5V or 3.3V voltage even if I connect the usb cable of SDCC to a general DC power supply instead of a computer? Since J33 pin keeps breaking down, I think it would be good to supply 5V, 3.3V DC voltage using SDCC. But I want to use ADC without ADS8698 connected to the computer, so if I use SDCC, I want to use SDCC only to apply DC voltage of 5V, 3.3V.

    And I have purchased 5 ADS8698-EVMs so far, and four of them have failed with the same symptoms. If I use DC power supply to apply external voltage to J32, J33 of ADC, there is no problem, but if I use the method I use to apply DC voltage to J32, J33, the 3.3V (J33) pin of the ADC board keeps failing. But the strange thing is that J32 is fine, but only J33 is broken, and I don't know why. If a voltage is applied to J33 using a dc power supply after the J33 pin of the ADC fails, the current will flow greatly and 3.3V will not be applied to J33. I think the current is flowing directly into the ground. 

    For your information, I was using linear power supply to change 220 VAC to +12 VDC, and then applying this +12 VDC to regulator LM317, and then applying the output voltage of LM317 to J32, J33. The picture below shows the circuit I'm using to generate 5V, 3.3V voltage. Is there something wrong with how I apply external voltage? If I use DC power supply, there is no problem, and if I use my regulator PCB, ADC breaks down right away, and I don't know why.

    - Actually you do not need external 5V and 3.3V power supplies, both supplies on the EVM have been connected to the SDCC (5V_SDCC and 3V3_SDCC) and take the power from the SDCC. The jumper on J13 should be put on pin 2 and 3 position, the jumper on J17 should be used to disable the U9, no jumpers on J12 and J14, the ADC can work without using U4/U5 amplifier and HVDD/HVSS supplies. If you want to use the U4/U5 amplifier, you will have to provide external EXT_HVDD and EXT_HVSS to J18 and use jumpers to connect pin 2 and 3 on the J12 and J14, you can not create HVDD abd HVSS supplies from the 5V supply of SDCC (5V_SDCC) because of current limitation from the USB port. Another way to use the EVM is, provide external +5V supply to J32, you can use the 3.3V from the SDCC or provide a +3.3V supply to the J33, however you should remove R78 when you connect the SDCC to the EVM,otherwise the board could be damaged because two supplies are connected together. Make sure all the  jumpers on right positions when you use external power supplies: pin2-3 on J13, a jumper on J17 if U4/U5 are not used. I do not understand your issue/fault, do you mean you made a mistake to connect the 3.3V input on J33 to the ground and apply a high current to J33 (+5V supply?)? then your EVM did not work? please clarify.

    : Thank you very much for your kind explanation. To sum up, there are four ways to apply DC voltage to ADC. Is that right?

    - Using SDCC
    1. To supply DC power using SDCC only without applying 5V or 3.3V from the outside. Connect 2 and 3 of J13, connect jumpers to J17, and remove jumpers from J12, J14. Note that at this time, the U4, U5 amplifier and HVDD, HVSS are not used (because the current is small, HVDD, HVSS cannot be created with 5V of SDCC)
    2. To apply 5V to J32 using a power supply and 3.3V voltage using SDCC. However, R78 must be removed to prevent board damage when using external voltage and SDCC at the same time. 2 and 3 of J13 must be connected by a jumper when using external voltage without U4/U5

    - Do not use SDCC
    3. If you want to use U4, U5 amplifiers, apply high voltage (from 16 V to 25 V) to J18 and connect 2 and 3 of J12, J14 respectively.
    4. Lastly, the way I've been doing it. To supply 5V and 3.3V to J32, J33 using a power supply.

    I haven't tried method 1 and 2 yet. So far, I've only used the number four method. And four EVMs have failed and are not currently in use. But if we use the method you told us, we might still be able to use faulty EVMs that do not have 3.3V applied to the J33 pin.
    By the way, I just tried using the number 3, but the ADC doesn't work. I used a DC power supply to connect -16V, GND and 16V to J18.1, 18.2 and 18.3 respectively, and 2 and 3 of J12, J13, and J14. J17 is closed, of course. Please let me know what the problem is.

    Thank you very much.

    Sincerely,

    Yunjae Park

    yjpark0128@snu.ac.kr

  • Hi Yunjae,

    Firstly, I want to clarify:

    When you use the SDCC to connect EVM to a computer, the 5V_SDCC or 3.3V_SDCC power supplies from the SDCC board have been connected the EVM board automatically, see the schematic in ADS8698EVM User Guide in page 40.

    If you want to use the SDCC only for applying DC supply voltage of 5V and 3.3V, this is NOT possible for you to communicate the ADC with your own CPU because all digital signals of SPI have already been connected to the CPU/FPGA on the SDCC board unless you can remove all series resistors or disconnect the signals on the J9 on the EVM to disconnect their connections from the SDCC. Otherwise, the digital signals connected to two controllers will affected each other. Hence, if you want to use you own controller, you can connect your digital signals to J1 connector on the EVM board without using the SDCC, also you need to provide external +5V power supply to J32 and +3.3V supply to J33.

    The phenomenon you described is correct, "apply DC voltage to J32, J33, the 3.3V (J33) pin of the ADC board keeps failing. But the strange thing is that J32 is fine, but only J33 is broken", because you need to remove R78 0ohm resistor and disconnect +3.3V supply from the SDCC board. J32 is fine because there is a protection circuit between the EXT_5V from J32 and +5V supply (5V_SDCC) from the SDCC board. However, there is no protection circuit between +3.3V from J33 and +3.3V supply (3V3_SDCC) from the SDCC board. See the schematic in ADS8698EVM User Guide in page 40.

    You can use external circuit to create +5V/+3.3V power supplies to J32 and J33  on the EVM board as I talked above, the only thing you need to do and pay attention to is, remove R78 before you apply an external +3.3V supply to J32 on the EVM. However, you need clean power supplies for the ADC to achieve a good performance specified in the ADC datasheet. LM317 has much higher noise, I do not recommend you to use it. TPS7A470A is a really good LDO I used for the ADCs in many designs which can provide much lower noise and ripple also can achieve pretty good system performance.

    Regrading your last question, your understanding about item 1 and 2 is correct , however:

    1. If you use the controller on the SDCC and the GUI for data capture, you do not need external power supplies since the SDCC already provides both 5V and 3.3V to the EVM board.
    2. If you use your own controller also want to use the SDCC to provide both 5V and 3.3V supplies, I do not recommend this solution unless you can disconnect all digital signals from the SDCC.
    3. If you use your own controller with external power supplies, you do not need the SDCC board.

    Your item 3 and 4 should be combined to one solution because both 5V and 3.3V supplies are always needed whatever you use U4 and U5 or not. For your experiment to use item 3, the ADC does not work as you described, this is a correct behavior because the ADC needs both 5V and 3.3V, you did not provide them with your jumper configurations. The AVDD/5V can only be created from your external 16V supply when you move the jumper on J13 from pin 2-3 to pin1-2. However you still need an external 3.3V supply to J33 connector on the EVM board without the SDCC.

    I strongly recommend you to check the schematic in ADS8698EVM User Guide before you do any test. I hope my explanation has been clear to you!

    Regards,

    Dale

  • Dear Dale,

    Thank you very much for your detailed reply. 


    1. I was using ADC by connecting the external voltage only and connecting the FPGA controller to J1. And I didn't use SDCC at all. You told me to remove R78 if I use SDCC and external voltage together, but should I remove R78 even if I do not use SDCC at all and supply 5V and 3.3V voltages only with external voltage?

    2. And is it normal for J32 to be intact and only J33 to fail when using external voltage 5V or 3.3V without using SDCC (without connecting simple capture card to J19)? 

    3. And can I connect the power supply, not the computer, to the USB cable of SDCC, use the controller through J1, and use it without any external voltage of J32, J33? (Use SDCC to supply 5V, 3.3V voltages only) And in this case, should I get rid of R78?

    I'm currently reviewing the regulator circuit, which generates a voltage at 3.3V, because I'm thinking that maybe J33 is out of order because I applied an overcurrent at J33.

    Thank you for your kind reply every time.

    regards,

    Yunjae Park

  • Hi Yunjae,

    1. No.

    2. No. However, J33 has no any connection to the ground on the EVM, so there is no way to have a current flowing from the J33 directly to the ground on the EVM.

    3. No, you can not use SDCC only for providing 5V and 3.3V supplies. Applying external DC power to J32 and J33 is one solution to provide the power supplies to the EVM without SDCC, another solution to provide the supplies is applying +5V power to pin2 of J1 (VBUS_LP) and +3.3V power to pin 1 of J1 (3V3_LP). Under any condition without SDCC connection, you do not need to remove R78. Check the schematic for power circuit in ADS8698EVM User Guide.

    The 3.3V DC supply to J33 is used for DVDD as a digital power supply to the ADC and EEPROM on the EVM and both devices only need small current.

    Regards,

    Dale

  • Hi Dale,

    You said that the current cannot flow directly from J33 to ground, but even if I connect the DC power supply to J33 and generate 3.3V voltage, 3.3V will not be applied. Why is this happening?

    Of course, this has not been observed since we started using ADC.

    If I use the DC power supply to generate 3.3V on the ADC that is not broken, 3.3V is applied and the current flowing at that time is about 1mA. I usually set the current limit of DC power supply to 50mA.
    But when I used the LM317 circuit to generate 3.3V and connect it to J33, the 3.3V was applied without a problem. After a few hours, however, the voltage applied to J33 was reduced to less than 2 volts, and several ADCs failed in the same pattern. If I use DC power supply instead of LM317 to generate 3.3V after this has been observed, only 0.5 to 2V voltage has been applied. At the same time, however, the current flows to the limit of the DC power supply. If I increase the current limit, the applied voltage increases, but not to the magnitude 3.3 V. Furthermore, attempting to apply a voltage of 2.9 volts requires an unusually large current of 500 mA.

    1. I thought the reason why this happened was because J33 in ADC was shorted to ground. Am I wrong?

    2. Whether J33 is shorted to ground or not, is the ADC that has been observed once no longer available?

    3. I also measured the current generated by the circuit using LM317 to see if I caused an over-current. If I connect 3.3k ohm to a circuit using LM317 and apply 3.3V, it only flows about 1mA. So I don't think the ADC failed because the circuit using LM317 generated an over current. In this situation, what should I try to do first with ADC malfunction?


    Thank you.

    regards,

    Yunjae Park

  • Hi Yunjae,

    Based on your description, something was damaged on the board when the J33 was connected to LM317's output for 3.3V power supply during the few hours. When the J33 was connected to the LM317, did you apply any signal to the board's or ADC's input? 

    1. J33 was not shorted to the ground in original circuit. The issue happened because some components were damaged in the circuit when the J33 was connected to LM317's output for some reasons, did you check if there is any short step by step with a multimeter but not powering up the board? if so, check D7, C61 before and after removing them. Also, please check C5/R13/R15/R18/C64/C62. I hope no connection on R96.

    2. I can not say whether the ADC has been damaged or not. Please check if there is a short on those external components above. If all of them were not damaged and shorted, you can desolder the ADC to check if the short is disappear, thus a damaged or shorted component can be determined.

    3. Please check step by step regarding the suggestions above to firstly confirm which component or device was damaged, then we can see how to avoid it.

    Best regards,

    Dale

  • Hi Dale,

    After reading your answer and testing the parts of ADC, I found that D7 was the cause of the ADC defect.

    Thank you very much for your reply.


    Have a nice day.

    regards,

    Yunjae Park

  • Hi Yunjae,

    I'm glad you have found the root reason to cause the issue by following the experiment suggestion, thanks.

    Best regards,

    Dale