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XTR305: Not getting output voltage

Part Number: XTR305
Other Parts Discussed in Thread: XTR300EVM, XTR300

Hello,

I've this circuit of XTR305 for Analog Output. Even if the output for DAC which is input to XTR305 is there, still XTR not giving output.

Below is the circuit I've prepared. Need help in what's wrong with circuit.

  

  • Hello Hrishikesh,

    The schematic of your XTR305 circuit does not display on the post above.

    Can you please re-post the XTR305 schematic showing the DAC drive circuit, specify the DAC voltage range, XTR supply connections, Rgain, Ros resistors and passive components, compensation capacitor, and load conditions.  Please also let us know the desired XTR305 output mode (voltage or current), and the desired voltage range (or current range).  Please specify the voltage or state of the XTR305 M1, M2 Mode inputs, Output disable input (OD) and the state of the error flags.

    Thank you and Regards,

    Luis 

  • Hello Sir, 

    Sorry for the schematic problem as I'm new to forum.

    Please find attached schematic.

  • I need output voltage in range of 0 to 10V.

    And also current form 0 to 20mA.

    Input will be from DAC in range of 0 to 4V and XTR output will carry accordingly. For ex. @ 4V from DAC, XTR will give 10V output, same for current.

    For voltage M1 and M2 will be low and for current M1 low M2 high.

    Also would like to cross check error flags as shown in schematic. Whether combining all flags are allowed or not.

    Thanks

  • Hello Hrishikesh,

    The XTR305 requires bipolar V(+) and V(-) supplies. The XTR305 datasheet specifies performance for a negative supply of V(-)= -5V. 

    Please connect the V(-) pin and EP to a voltage supply of -5V, and ensure that both V(+) and V(-) supplies and all analog signals are referred to the same ground potential (AGND).  (The schematic above shows the V(-) and EP connected to a different chassis GND?). 

    On voltage mode, with M1=M2=Low, the XTR305 may require a compensation capacitor for loop stability if the application requires to drive a large capacitive load.  Please review the section 'Driving Capacitive Loads and Loop compensation' of the datasheet on page 26 and the circuit on figure 35.  The Cc value can be determined using the empirical procedure explained on the datasheet, or alternatively using the TINA SPICE macro-model.  If you require assistance let us know what is the max capacitive load required on the application and the value of C16. 

    It is possible to connect the Error Flags in parallel, but the user will loose the ability to distinguish between the different errors.

    Thank you and Regards,

    Luis

  • Hello Sir,

    As per your reply, I've connected bipolar supply of V+ (+15V) and V- (-15V). 

    All the peripherals are referenced to same Analog Ground.

    V- and EP are connected to same ground just the symbol is different as I've used Half Moon and it is shorted.

    Please find the attached image for DSO which I got after doing changes. It going in negative with potential of 10V.

    Need your help to get 10V output.

  • Hi Hrishikesh,

    Diode D7 on the schematic above is a dual schottky barrier diode. 

    The schematic above shows D7 is referred to (V+) and ground. Assuming D7 is connected to the same ground potential, diode D7 would work as a clamp.  The schottky diode would clamp and not allow the XTR305 output to go more negative than approximately -0.6 or -0.7V. Since the output is able to yield negative voltages, this suggests that the ground connections and/or supply connections are not connected properly; or the devices are not connected as shown on the schematic above.

    Please re-verify all the supply and ground connections on your PCB board and replace the XTR305 with a fresh device in case the device has been damaged. Also, the compensation capacitor CC is still missing in the schematic.  The device also requires supply bypass capacitors as recommended on the datasheet.

    Please refer to the XTR300EVM schematic and the XTR300EVM User Guide for an schematic and PCB board layout design example. The XTR300 is essentially a pin compatible device, with slightly better offset/linearity.

     After revising the schematic and PCB layout with the required changes, please install a fresh XTR305 device and perform the tests.

    If issues continue, please provide the following information:

    - After correcting the schematic and layout, please share the complete updated schematic showing the correct supply and ground connections, with all connections referred to the same ground.

    - Please share / post the corrected/updated PCB board layout .

    - Can you show the input voltage VIN along with VOUT on the oscilloscope plots above?

    - What is the capacitance value of C16?  

    -What is the voltage on M1 and M2 when the issue occurs?

    Thank you and Regards,

    Luis

  • Hello Sir,

    I've done all the changes in PCB as suggested.

    I'll try using a fresh device and check.

    Meanwhile please find the attached updated schematic for the changes done. Sorry for hand drawn schematic.

    Also, I've removed the D7.

    I'll try to capture all the waveforms and share with you.

    Thanks,

    Hrishikesh

  • Hello Sir,

    Changing a new XTR305 just solved my issue.

    Thanks for your kind support.

    Hrishikesh

  • Hi Hrishikesh,

    That's good news. I am glad to hear that the issue was resolved.

    The latest schematic looks good, a suggestion is to add 10uF+100nF bypass capacitors on the +15V and -15V supplies (and optional TVS diode for overvoltage protection on the supplies).  Also, add a bypass capacitor on the +5V supply

    Thank you and Regards,

    Luis

  • Hello Sir,

    Yes definitely I'll add in new revised Schematic and PCB.

    Thanks for your kind support.

    Hrishikesh