Power Isolation

[electronicsLearner77]

I have the following board


As shown the board is a single board with some part for microcontroller powered by 5V, there 3 ICs for gate driver which are powered using 12V supply. It works well as long as i do not switch on PWM, but once PWM is on a huge current is drawn from 5V supply and micro fails. The design is that the current shall be sourced from 12V, but that does not happen. What is the reason? Please advise.

 

[danadak]

I have the following board
View attachment 58716

As shown the board is a single board with some part for microcontroller powered by 5V, there 3 ICs for gate driver which are powered using 12V supply. It works well as long as i do not switch on PWM, but once PWM is on a huge current is drawn from 5V supply and micro fails. The design is that the current shall be sourced from 12V, but that does not happen. What is the reason? Please advise.

Could be MOSFET gate drivers are supplying gate current via 5V supply ?

How much current are you seeing ? Any scope screen captures of micro power rail ?


Regards, Dana.

 

[Harald Kapp]

Looks like 5V and 12 V use separate grounds (GND). You need to connect the grounds to create a common GND reference potential.
Nothing more can be said without knowing more detail of the circuits involved.