LM5002: High side switch for

Hi Bhanu,

thank you for using the E2E forum.

I am not sure if I understood your question.

Would you like to use the LM5002 or a microcontroller for the Boost control?

Best regards,

 Stefan

Hello Stefan,

                    In the current setup as shown in the schematic even if the LM5022 is disabled we still get the applied 48V at the output.

So we were planning to put a mosfet as a switch at the input to the BOOST.

We wanted to know which type of mosfet switching mechanism can be used. The mosfet should be controlled by a microcontroller 5V output pin.

Thanks 

HI Bhanu,

as the switch needs to be on the high side this cannot be controlled directly from a microcontroller running at 5V.
The Gate signal needs to be near the input rail (a few volts above or below depending on the MOSFET type).

It might be easier to select another controller for the SMPS, e.g. LM5121

Best regards,

 Stefan

Hello Stefan,

                     Thanks for the information. Would it be good if we implement a switch on the Low side?

As that mosfet can be controlled using a Microcontroller we think.

Thanks

Hi Bhanu,

yes, this would be much easier as a npn type MOSFET can be used then.

Best regards,

 Stefan

Hello Stefan,

                    So if we want to implement a N channel enhancement  mosfet as a low side switch for the above circuit how would we go about implementing it as im having some confusion. Would really appreciate the help

Thanks

Hi Bhanu,

as already mentioned, i suggest using a device with control for a high side switch. Switching on the low side needs to be considered the application behavior and requirements as you then have the switch between the GND and all side effects from that needs to be considered.

Best regards,

 Stefan

Hello Stefan,

                      Thank you for the information.

I just one follow-up question.

Would the above circuit work well for switching 48V rail. Here the +12V would be replaced by 48V.

Thanks