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TIOS1013: LDC0851 - power supply compatibility

GWC_NZPA
Prodigy 10 points
Part Number: TIOS1013
Other Parts Discussed in Thread: LDC0851, , TIOS1015

Tool/software:

The LDC0851 requires a "Fast supply" to avoid having to include an RC filter on the Enable pin. Is the TIOS1013 supply ramp faster than 4.2 mV/us with a 0.1uF load?

The TIOS1013 regulator output graphs in the datasheet do not have enough detail for me to work this out.

Thanks,

  • 0
    TI__Mastermind 34930 points

    Are you asking about the VCC_OUT ramp rate with only a 0.1uF filter capacitor?  If so, then there is an issue with the request because the LDO needs at least 1uF for stability.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Prodigy 10 points

    Hi Jonathan,

    Yes, good point, let me rephrase my question as what is the VCC_OUT ramp rate with a 1.1uF filter capacitor? Is it faster than 4.2 mV/us?

    Thanks,

  • +1 in reply to GWC_NZPA
    TI__Mastermind 34930 points

    I don't have an exact ramp rate at the moment because this isn't a specified parameter in the datasheet.  I have a scope plot of the 5V version (TIOS1015) that shows the ramp rate with a 1uF cap.  This plot shows a full ramp took approximately 130us, and therefore, I would say the TIOS1013 will not be able to meet your 4.2mV/us ramp rate requirement because the TIOS1013 and TIOS1015 differ in the voltage level but have similar ramp rates and other functional timing specifications.

    Channel 1: VCC (24V)

    Channel 3: VCC_OUT (5V)

    Channel 2: Unused

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Prodigy 10 points

    Thank you Jonathan, that is the information I needed.

    Though I think it is a suitable ramp rate as it needs to be > 4.2 mV / us,

    5000mV/130us = 38 mV/us > 4.2 mV/us

    Best Regards,

  • +1 in reply to GWC_NZPA
    TI__Mastermind 34930 points

    That is correct.  Sorry, I misinterpreted your question and for some reason was associating "faster" with "less than <" when you are correct it is actually a "greater than >".  Just a mental mix up on my behalf.

    Regards,

    Jonathan