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LM5030: How to implement Sequencing ON/OFF control and soft-start function at the same time with SS pin

DEEPAK V14
Intellectual 810 points
Part Number: LM5030
Other Parts Discussed in Thread: LM8364

Hi,

we have an application where the LM5030 has to be Power-ON with outputs disabled(ie No PWM at Out1 and Out2).
At the same time, soft start capability of the LM5030 should be able to use when it is enabled.

For this, we plan to drive the 'SS pin' from the GPIO of uC/FPGA. GPIO is a normal one, not an open-drain pin.
It can't ensure that GPIO will be at Ground during initial Power-ON or during Reset.GPIO may be at high impedance state during Power-ON or during reset.
But it has to make sure that LM5030 is not turned on when GPIO is at high impedance or ground during Power ON or Reset.
LM5030 outputs have to enable only when only when GPIO is at logic high(3.3V). Along with Soft-start timing requirement of 2seconds also have to meet once LM5030 is enabled.

Question1. Please give me some suggestions for implementing the circuits to realize the above requirement?


Thanks in advance
DEEPAK V

  • 0
    TI__Mastermind 26215 points
    Hi Deepak,

    Thanks for your interest in LM5030. I would take a look at using a undervoltage sensing circuit like LM8364 to drive the SS pin. At the input, you can place a pulldown resistor which would trigger the undervoltage and the LM8364 will pull down the SS pin through its open drain output. So if your GPIO is logic low or high impedance, LM5030 will remain disabled. When you drive the input of the LM8364 high, it will release the SS pin and LM5030 can then go through its soft start sequence.

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    Intellectual 810 points
    Hi Ben Lough,

    Thank you for helping with one of the simple solutions.

    Thanks and regards
    DEEPAK V