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TPS63030 Ripple in PS Mode

Charles Gervasi
Expert 2270 points

How much ripple should I expect in PS mode?

In the thread at this link, a user says the datasheet shows 100mV ripple in PS mode.  I do not see this in the datasheet. 

I am seeing 100mV.  I have been experimenting with my board.  When I had 10uF output capacitance, I saw 200mV ripple.  Going to 100uF reduced it to 100mV.  I am going to stuff a board with just the supply and put a resistor on for a load to eliminate anything else going on on my board. 

My input voltage is 3V and the output voltage is around the same. I'm using a 2.2uH inductor.  My system spends most of its time drawing less than 1mA from the power supply output.  What can I do to reduce this ripple?

When PS is operating correctly, roughy how much current should I expect the the power supply to take when the output current is 100uA?   Should it be closer to 100uA, 200uA, 1mA or 5mA?

Thanks!!

CJ

  • 0
    Expert 2270 points

    I have done testing on a board with only the power supply on it.  Here is what I found:

    • Quiescent current is in the 40uA range, and that appears to be the only overhead when little or no load is present at the output.
    • Ripple = 150mV regardless of load ( < 100uA tested).  Rise time is 4us regardless of load.  Fall is RC exponential decay. 

    Question:

    • Is there a way to change the amount of hysteresis in the PS loop so that ripple is significantly lower?
    • Are there any tips on filtering this ripple out when using CC430?  We believe this ripple is causing the radio to become non-responsive intermittently.  
  • 0 in reply to Charles Gervasi
    Expert 2740 points

    Try adding an external LC filter. I would start with 100uH and 0.1 uF ceramic capacitor.

    Peter