[GSoC Daily Log]: Weird voltages!

Friday, 30th May 2014:

  • Testing PCB for life signs
  • Setting up I2C test setup. I2C scan doesn’t show up AD9984A, whereas shows 2 other PCF8574A test devices on same bus. Something’s wrong.
  • On Powering up the PCB with 5V VCC. Power Supply Problem noticed.
    • OVDD: 3.35, Fine
    • PD: Expected voltage: 1.8V. Actual measured: 0.55-0.58 V, Critically Low
    • VD: Expected voltage: 1.8V. Actual measured:0.39V, Critically Low
  • May be due to OVDD having ADP3303-3V3 whereas PD and VD have ADP3334
  • Assuming problem with 1.8V LDO, Ordered samples for fixed voltage (1.8V) LDOs from TI and Analog Devices (SOIC and SOT23). Lets see if they get approved for samples!  

UPDATE: 
Found the reason for the weird voltages! 
Seems there was a slight mistake in feeback circuit designing which led to this major problem! Will post details in the weekly log! Trying to fix it in meantime for making the PCB usable.




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