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TPS7H1111-SP: Output Impedance

Anthony Flores
Prodigy 30 points
Part Number: TPS7H1111-SP
Other Parts Discussed in Thread: TPS7H1111EVM-CVAL

Hi,

Is there any output impedance data for the TPS7H1111-SP?

I've simulated the output impedance at 0A and 1.5A using 2x100uF output caps and also simulated with a 1nF cap. 

How does the simulation match up to the data?

  • 0
    TI__Expert 7870 points

    Hi Anthony,

    The only impedance data I have immediately on hand is for an unpowered TPS7H1111EVM-CVAL EVM. That data basically shows the impedance of the 2x 100uF output capacitors on the default EVM, which does line up very well with the equivalent simulation - though that's more a statement of the validity of the capacitor models than the device model. Your results appear to align with the 2x100uF COUT caps in the expected middle frequency range.

    We may be able to gather more impedance data, but this would take some time to set up. Let me look into this and see if I can provide an estimate.

    Thanks,

    Sarah

  • 0 in reply to Sarah Koch
    Prodigy 30 points

    Hi Sarah,

    More impedance data would be very much appreciated.

    Thank you for looking into this.

    Best,

    Anthony

  • 0 in reply to Anthony Flores
    TI__Expert 7870 points

    Hi Anthony,

    No problem. I will update you here once I have a more concrete estimate of the timeline. 

    All the best,

    Sarah

  • 0 in reply to Sarah Koch
    TI__Expert 7870 points

    Hi Anthony,

    I was able to get a few measurements today to compare against. The measurements are taken from the pads of C16 (non-populated) on the default TPS7H1111EVM-CVAL board (2x 100uF caps). The traces are:

    - Noise Floor

    - Device off / No load

    - Device off / 1.3 Ohm (1.38A) Load

    - VIN=2.5V / VBIAS=5V / VOUT=1.8V / No load

    - VIN=2.5V / VBIAS=5V / VOUT=1.8V / 1.3 Ohm (1.38A) Load

    Towards the lower frequencies, you can see the measurements were beginning to run up against the noise floor. The PCB also likely has some influence that is not captured in the simulation, so I would expect some impact from that. Overall, the results do appear to align at least for the default EVM configuration.

    Thanks,

    Sarah