LM43601: Inverting Buck-Boost, how long is the power off time?

Hello Shinichi1,

Power up is controlled by soft start while power down is normally controlled by the load. The LM43601 uses diode emulation so does not pull down (actually up in this case) its output. The load and output capacitance determines how long it takes for the output to collapse.

Regards, Robert

Hi Robert,

Thank you for your reply.

As you mention, the power down time is determined by the load and the output capacitance.

In this case, I think it can calculate the equation CV=iT
At the SNVA722B, C=47uF+1uF, V=-15V, i=1A
T=0.72ms
Is it correct?

The customer'd like to know the actual value.
If possible, could you please show the actual value of the circuit(SNVA722B).

I appreciate your great help.

Best regards,
Shinichi

Hello Shinichi,

Your calculation is correct. In most applications, the current draw is not constant with voltage so your results will vary based on the properties of the load.

Have you checked the inverting Buck-boost design for the LM43601 in Webench? You can run simulations for this design.

Regards, Robert

Hi Robert,

Thank you for your reply.

I'll share the calulation with the customer.

I have used WEBENCH, but it can't simulate.

Could you please let me know how to do electrical simulation.

https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=E1FACBCB782AAA56

I appreciate your great help.

Best regards,

Shinichi

Hi Arief,

Thank you for your reply.

I understand the way to download.

I appreciate your great help.

Best regards,

Shinichi