TPS40090 / TPS40091: What is the relationship between the SYNC frequency and the PWM switching frequency?

What is the relationship between the frequency applied to the EN/SYNC pin and the frequency generated at the PWM outputs?

Peter James Miller

New Product Development Engineer

Power Management - DC/DC Solutions - High Performance Solutions

Member Group Technical Staff 2008

  • What is the relationship between the frequency applied to the EN/SYNC pin and the frequency generated at the PWM outputs?

     

    The TPS40090 controller's internal synchronization circuit uses an internal divide by 2 synchronization circuit to produce a 50% duty cycle SYNC signal and then multiplexes this signal to the PWM outputs.

    In 2-phase or 4-phase modes, the PWM output frequency is 1/4 of this divided signal (4-phase multiplexed) generating a 1/8 switching frequency at the PWM output.

    In 3-phase mode, the internal frequency is multiplexed over 3 channels to generare a 1/6 switching frequency at the PWM output.

    The TPS40130, TPS40131, TPS40132, TPS40140 and TPS40180 use similar clocking schemes, producing the same divide by 8 or divide by 6 relationship between their SYNC or CLKIO inputs and their switching outputs.

    Two TPS40090/91 controllers using a 180 degree out of phase 50% duty cycle SYNC pulse train will synchronize 45 degrees out of phase at 1/8 the switching frequency.  It is not possible to synchronize two 2-phase TPS40090/91s 90 degrees out of phase (They will be randomly 0 or 90 degrees out of phase, depending on the divide by 2 state at start-up)

    Also Note:  Since the TPS40130/131/132 uses the same divide by 8 scheme is also used for the TPS40130/131/132, it is not possible to synchronize two TPS40130/131/132 controllers 90 degrees out of phase.

    Peter James Miller

    New Product Development Engineer

    Power Management - DC/DC Solutions - High Performance Solutions

    Member Group Technical Staff 2008

  • In reply to Peter Miller13277:

    I have a question about TPS40090,How to get “TPS40090 Pspice model”for simulation?

  • In reply to Roger Ding:

    Hi Roger,

    I don't think we have Pspice model of TPS40090/91 so far.

    Regards,

    Na

    Na Kong
     
    Applications
    DC Solutions
    Power Management
    Texas Instruments
  • In reply to Na Kong:

    All available Pspice models can be found at:

    http://www.ti.com/spicerack

    or in the product folder.  If you need a model that is not available, you can contact the Product Information Center by going to www.ti.com and clicking on technical support. They will assist you in determining if a model can be provided.