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.

TPS62203 - Extremely Unstable Output

Other Parts Discussed in Thread: TPS63050

I'm wanting to power an xbee from 3C batteries. I've followed the suggested layout from the documentation however, when I check the voltage I get anywhere beteween VCC which is around 4.8 volts with 3 fresh batteries down to 2. somethings. The voltage seems to cycle. What am I doing wrong here? Attached is my PCB layout and schematic. I'm using ceramic capacitors and this inductor: Taiyo Yuden CBC3225T100KR

  • Why do you use such an old IC?

    Your schematic says 4x AA batteries, but your text says 3x. What do you have?

    The traces to and around the IC are very thin. These need to carry some current, so they should be thicker.

    The layout isn't zoomed in enough on the IC to tell anything, but it looks not ideal with all the thin traces and lengthy ground connections.
  • Searching for an IC that could output 300 ma this one came up on digi-key so I went for it. As for the number of batteries, I initially designed it with the intention of using 4 aa batteries. However I've been using 3 c batteries to test it this weekend, which should still work well. The traces in and out of the IC are 15 mil, which I thought would be sufficiently wide. What would your recommend? ... since you mentioned it I notice the suggested TPS6224, would it be worth an attempt at dropping one of those in?
  • 15 mil is really thin. These are carrying current.

    Can you post a waveform of Vin, Vout, and SW which shows the oscillation?

    The difference between 3 and 4 batteries is critical because 4 fresh batteries puts you above the 5.5V or 6V range of many ICs, including this one.

    As well, you will only get 3.3Vout when the batteries are at a higher voltage than this. So, you can only discharge the batteries to ~1.1V per cell, which most would consider as still usable (not completely discharged). For this reason, most use a buck-boost converter like TPS63050 when a 3.3V rail is needed from such a power source.