LMZM33606: Controlling power down behaviour

Hi,

You may want to try to use level shifter to shutdown the LMZM33606 such that the EN signal can be shut down based on a more precise manner. 
Below article may have some example on how to achieve this

https://www.ti.com/lit/an/snva856a/snva856a.pdf?ts=1643817792697&ref_url=https%253A%252F%252Fwww.google.com%252F

Also the rate of discharge would depend on the load on each rail and its output capacitor. 

Is it also possible to shutdown the negative rail first and followed by the positive rail?

Thank you

-Arief

Hi Arief

Thanks for your reply. We are currently using a similar enable control scheme - both the LMR23630 and LMZM33606 are enabled from the same signal (with the level shifting for the LMZM33606). 

The difficulty with changing the shutdown is that we would need different timing for startup vs shutdown, otherwise we would get the right timing for shutdown but ruin the timing on startup (which would also cause the amplifiers to generate large voltages). 

I had tried to add a large load to the -15V rail to increase the discharge rate - it made no difference before but I will try again.

Hi Jordan,

I acknowledged this one is quite a tricky problem even when we know the reason for the behavior. One passive way to do it to maybe put a clamp on the output such that even with the voltage spikes, it is still being clamp to a manageable voltage. 

Another thing that i can think of, since the LMZM33606 have a SS/TRK pin, i wonder if we can use the pin to track the positive output voltage. This way hopefully the Opamp will be powered down at the same rate between + and - rail. 

I have not tried this before but maybe that is something that can be experimented with. 

Thanks

-Arief

Hi,

I hope you find a solution for managing the shutdown of negative rail. 

I will close the thread for now, but feel free to re-open it if you have any further questions

Thanks

-Arief