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LTM4636 - RUNP and RUNC Enable Sequencing

Category: Datasheet/Specs
Product Number: LTM4636

In the LTM4636 datasheet, it states that the RUNP needs to be enabled first and then RUNC.  I understand the need for sequencing, but in my initial design, there was an error where RUNP and RUNC were enabled simultaneously.  I have since corrected this issue, but the module fails to output a VOUT voltage.  All the other INTVcc / PVcc voltages are present and everything seems okay, except the output.

My question is this.  Did my initial sequencing issue cause permanent damage to the device, and does it need to be replaced, or is the device okay as long as the power sequencing ramp-up now follows what the datasheet states?

Thank you,

  • Follow up note.  In comparing my design with the evaluation board I discovered that the COMP pin on the evaluation board is 0.613V when the device is enabled, which matches the LTSpice model.  On my design, the COMP pin when the device is enabled is 2.19V.  I tried looking at what this specifically means in the datasheet, but there wasn't a direct answer.  Can this difference indicate that the part is damaged, or what exactly does this difference mean and hopefully it can help me debug my circuit.

    Thank you

  • Follow-up note to my follow-up note.  Resolved the issue.  The problem was with the TMON pin.  I had it connected to an Altera MAX10 ADC input.  This pin properties were somehow causing the LTM4636 to believe it was in thermal shutdown mode, so the TMON pin isn't just a temperature indicator; it can also disable the device.  I removed a series resistor between TMON and the FPGA, and the device started working immediately.  Hopefully, this helps someone who runs into a similar situation and doesn't know where to look when debugging.