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Original question:

TPS55340EVM-017: High output ripple for EVM..

TPS55340EVM-017: Using schematic for positive rail input of a bipolar DAC: Howto measure noise and ripple

Stefano Alfredo La Spina
Prodigy 240 points
Part Number: TPS55340EVM-017
Other Parts Discussed in Thread: DAC7716,

Tool/software:

Hi forum.

I have used as a reference the EVM described including the schematic hints in order to design the +24V positive input rail of a bipolar DAC (TI7716).

The DAC is used to generate continuous 5x500us pulses of fixed voltage (e.g. +20V) every 10ms and here comes the question.

How can I measure the ripple and the noise of the power rail for such a pulsed waveform?

Should I first perform a constant load test using a DC load on the output to see how it works?

Should I investigate the output of the DAC to see if there are some problems?

I have basic knowledge of mesuring such parameters apart some tips to avoid unwanted noise coupling.

Any help would be very appreciated.

Best regards.

  • 0
    TI__Mastermind 23770 points

    Hi Stefano,

    The ripple and noise may come from the switching frequency and load transient.

    From my understanding, DAC7716 will only draw a few mA. If this is the case, the switching ripple should be dominating.

    You may refer to TPS55340EVM-017 user's guide section 4.5 Load Transients, 4.7 Output Voltage Ripple and 4.8 Pulse-Skipping Operation for reference.

    Best Regards,

    Feng