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TX-SDK-V2 Power Supply Setup

Sean H
Prodigy 60 points

Hi,

We have purchased the ultrasound transmit solution (TX-SDK-V2), and have questions regarding power supplies for it. For the +/- 50 V power (for LM96550), what should the current rating be? On the Eval Kit User's Guide, it says that +/-50 V supply needs at least 250 mA capability. But the LM96550 data sheet lists no more than 40 mA total for all of its power inputs. Can we power supplies with current rating less than 200 mA?

Another question is that for Vsubstrate (-50V), can it be the same rail as the negative rail of the +/-50V? Does it have to be a separate power supply outputting the -50V?

Sean

  • 0
    TI__Mastermind 18285 points
    Sean,

    We have received your post and hope to have a response back to you soon.
  • 0
    TI__Intellectual 1560 points

    Hi Sean,

    Depending on your application. For CW mode, the +/-50V (VPP & VNN) supplies need to be able to source 250mA. Also, the +/-50V (VPP & VNN) supplies' absolute values have to less than 10V. Otherwise, the device will not be able to dissipate all the power. For B-mode or pulse mode, the +/-50V supplies will only need to source around 20mA.

    It's not recommend to tie the Vsubstrate to the -50V supply (VNN). The output can be as much as 20% peaking because of the transducer . As a result, Vsubstrate is not the most negative. If the output has around 5% peaking or less, Vsubstrate can be the same rail as the -50V (VNN) supply. However, one has to be very careful during power up and power down sequence. The -50V has to be turn on first and turn off last. If you are using it in CW-mode, make sure the Vsubstrate is the lowest voltage since usually VPP and VNN is less than 10V and VDN is at 10V.

    Regards,

    Charles

  • 0 in reply to Charles Guan
    Prodigy 60 points
    HI,

    Thanks for your reply. Could you explain what you mean by "the +/-50V (VPP & VNN) supplies' absolute values have to less than 10V"? Do you mean that the absolute value of +50 rail and the absolute value of -50 rail must be within 10 V of each other? ( |+50 supply| - |-50 supply| must be less than 10 V?)

    Sean
  • 0 in reply to Sean H
    TI__Intellectual 1560 points

    Hi Sean,

    The +50V rail (also name VPP) has to be less than 10V. And the -50V rail (also name VNN) has to be greater than -10V.
     Remember this condition only applies for CW mode.

    Regards,

    Charles

  • 0 in reply to Charles Guan
    Prodigy 60 points

    Thanks for the reply.

    Some comment and questions on the order of the power-up procedure:

    In the TX-SDK-V2 Eval Kit User Manual, the power-up procedure mentioned that the HV Pulser should be powered up last. The HV pulser has three different input voltages: +/-10V, +/-50V, and +/-40V. The manual did not mention specify on the power-up order for +/-50V and +/-40V. It only stated, in the last check mark, to power up +/-50V for the Pulser.

    Does the +/-40V must be turned on BEFORE the +/-50V? A caution message below the procedure stated that Vpf must be higher than 36V and Vnf lower than -36V at all times, which leads me to think that +/-40V must be turned on before +/-50V. I think I misread that caution message at first, and turned on +/-50V before +/-40V. And as a result the LM96550 was damaged.

    Also, I have separate power supplies for the positive rails and negative rails (non-tracking). If there is a delay between turning the positive and negative rails on, would that damage the system?

    Please let me know if the below sequence is accurate:

    1. Power up Vsub

    2. Power up +3.3V

    3. Power up +1.8V

    4. Power up +/-5V

    5. Power up +/-10V

    6. Power up +/-40V

    7. Power up +/-50V

  • 0 in reply to Sean H
    TI__Intellectual 1560 points

    Hi Sean,

    The caution should say VPF must be higher than VPP-14V and VNF must be less than VNN+14V at all times. This applies also when VPP is ramping from 0V to 50V, VPF has to be greater than VPP-14V. See attach file for power supplies configuration.

    Regards,

    Charles

    TX_SDK_V2 LM96550 Lab Bench Power Supply Setup.ppt