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Original question:

TPS53647: EN and VR_RDY

WEBENCH® Tools/TPS53647: TPS53467 Constant Current Output

Vilal Abo Abdo
Prodigy 30 points
Part Number: TPS53647
Other Parts Discussed in Thread: TPS53681

Tool/software: WEBENCH® Design Tools

Dear

I need know if is possible make a Circuit with a Constant Current Output using the TPS53467? For example: if the load have very small resistive value and request up than of 100A but i need give only 80A of Constant Current, is possible set the circuit configuration from Pinstrap or NVM for get a precise and constant current output?. Thanks

  • 0
    TI__Intellectual 1790 points

    Hi,

    This controller is constant output regulator, and not possible for constant current mode.

    Thanks.

    Regards,

    Rama.

  • 0 in reply to Rama Pamidi
    Prodigy 30 points

    Hi dear

    Thanks for you quick reply. I am reading the TPS53467 Datasheet and I find this section:

    Overcurrent Limit (OCL)

    The TPS53647 device includes a valley-current-based limit function by using a per-phase OCL comparator. A
    resistor connected between the OCL-R pin and the VREF pin generates the OCL comparison threshold.
    Using the valley current limit, the OCL current level can be selected using Equation 5. To set the per-phase OCL
    threshold, subtract half of the ripple current from the maximum average current and select the OCL threshold
    specified in the table equal or slight lower than IOCL.

    This instantaneous current sense voltage VCSPx is compared to the OCL threshold. If the current sense voltage at
    OCL comparator goes above the OCL threshold, the device delays the next ON pulse until the current sense
    voltage drops below the OCL threshold. In this case, the output voltage continues to drop until the UVP threshold
    is reached.

    Overcurrent Protection (OCP)

    Another overcurrent protection (OCP) is based on the current sensed through IMON pin of the device. When the
    digitized IMON is higher than OC_FAULT_LIMIT (1.25× IMAX by default), the controller turns off both high-side
    and low-side MOSFETS and enters into hiccup mode until the overcurrent condition is removed.


    According to the previous paragraph, then does mean that the IC can operate with constant current output?

    Thanks for you cooperation.

  • 0 in reply to Vilal Abo Abdo
    TI__Intellectual 1790 points

    Hi,

    System has two current limits for protection: OCP and Valley current.

    OCP: If system current reaches to this value, it shutdown with IOUT_OC fault.

    Valley current limit: it is cycle by cycle per-phase current limit. if system operate at this limit, output voltage reduces and system shut down with VOUT_UV fault (default = 200mV). _VOUT_UV_FAULT_RESPONSE can not be changed,  and the controller will shut the device down immediately and will attempt to restart after a 22 ms delay.

    Thanks.

    Regards,

    Rama.

  • 0 in reply to Rama Pamidi
    Prodigy 30 points
    Hi,

    Thank you for you reply and apologize for my insistence. In the Datasheet ask:

    If the current sense voltage at
    OCL comparator goes above the OCL threshold, the device delays the next ON pulse until the current sense
    voltage drops below the OCL threshold. In this case, the output voltage continues to drop until the UVP threshold
    is reached.

    What happens if UVP never reach UVP threshold and not detect how a OCP fault?.

    In the Datahseet ask the UVP can be adjust with the Command: MFR_SPECIFIC_22, then, it mean I can set the UVP in the NVM with UVP little high value for avoid detect as a OverCurrent Protection?, or not is possible?. Thanks

    Vilal
  • 0 in reply to Vilal Abo Abdo
    TI__Intellectual 1790 points

    Hi,

    in this case, TPS53681 controller is recommended. In this, VOUT_UV_fault response can be set as ignore.

    OCP can be set higher than per-phase valley current limit(OCL).  so System works in valley current limit, but IOUT average depends on inductor current ripple.

    Thanks.

    Regards,

    Rama.