Tool/software:
Hi,
In this Gate Driver Power Supply "Selected CVEE_GD value, CVEE_GD =" value we have choosen lower than the "Maximum CVEE_GD value without triggering VEE soft-start time-out" value. But still its showing in red. What will be the effect of choosing higher value. Please find the attached calculation sheet for more information.
Thanks and Regards,
Abdul
UCC34141-CALC-V1_CT.xlsx
Hi
From the Excel spreadsheet you attached, you have your minimum voltage ripple set to 1% (Excel cell C22, C23) which is very aggressive and this is resulting in a very high minimum required CVEE_GD capacitance that is close to maximum allowable CVEE_GD capacitance. This leaves a very small window for selecting a CVEE_GD value that can satisfy both conditions. Even just setting the required minimum ripple voltage to 2% instead of 1% will allow more headroom for choosing a capacitor value that will meet your 2% ripple requirement AND remain below the maximum allowable CVEE_GD. Your question about what happens if you choose CVEE_GD above the recommended maximum of 21μF: Choosing CVEE_GD>21μF will result in longer VEE soft start time that will trigger the VEE soft start timeout protection. You will see the output start to rise but then shutdown. The soft start timeout time is specified in the UCC34141-Q1 data sheet as highlighted below:
Steve
