Shutdown and then soft start for LM5021?

[cupoftea]

Hi,
Supposing i want to shut the LM5021 down and then restart it with a soft start....can i do this by shorting out the SS pin capacitor and then letting it charge back up?.. (obviously shorting the COMP pin temporarily to ground at the same time.)

I appreciate i can get a soft start by temporarily shorting VIN to ground (or <7V) , but that'll take more components.

 

[tepalia02]

To implement a soft start or shutdown sequence, simply shorting the SS (Soft Start) pin capacitor and momentarily grounding the COMP (Compensation) pin might not be a reliable or safe method. This method can cause unpredictable behavior or damage the device.

 

[cupoftea]

yes you're right, but its a current source output, so should be ok.?

 

[cupoftea]

Drat, it looks like im going to have to put in a NPN/PNP combo and a few resistors to turn off the Vin to the LM5021 during under voltage input, so that it soft starts back.....and i dont really have room.

I have a 24Vin...so i have a bleed resistor from LM5021 vin to that...and also a diode connected 12v bias rail to take over after the vin has gotten up to startup (20v)....i am windering if i dont bother to switch out the bleed, will the soft start cap then get charged up via the bleed alone? (bleed = startup resistor)...i dont want it too...since i want soft restart.