LM5576: LM5576MHX start-up problem

Hello

Here are my thoughts:

1. Please use the component calculator on our web page for this device and compare your

component values with what the calculator indicates

2. Try to disconnect the bqxxx device and see if the LM5576 will start reliably.

3. Try to increase the soft-start time, by increasing the soft-start capacitor.

Thanks

Thank you for the input, changed the soft-start cap and still no change.  The bQ has been removed from the equation for this part of the troubleshooting. At the output from the inductor of the LM5576 we get a solid +5V, so for our next test we placed a 5 ohm load resistor to ground, producing a 1A load at +5V.  The LM5576 immediately went into the error condition with the voltage ramp as posted earlier.  When the load was removed the error condition persisted requiring power to be removed from the LM5576 part to clear the issue.

Question:

When an over current condition presents itself, does the LM5576 fold back the voltage and should it resume proper operation when the current issue is cleared?

In my test case I was loading the output with 1/3 the rated current of the part, yet it appears to have errored out.  Are there any pins on the part that can echo an internal error that can be monitored to validate the current issue (if that is the case)?  From what I am seeing the load current is causing the error, and the error is not clearing once the load is removed even though the load was not outside the expected drive of the circuit.

Thank you for your direction,

Allan

An additional note.  We added an external capacitive load of 220uF on the +5V and simply the process of powering up the system caused it to fault, so it is definitely an issue with some sort of inrush current causing the part to fail proper operation, and the error condition not clearing itself when the issue is cleared.

Allan