LM5085: Current limit function

Same problem

Best regards,

Ap

Hi All:

Can I know the configuaration of your schemtic? using default TINA mode, the result looks good( 40uA*2.55k/20mohm=5.1A)

pls let me know you input, output and current limit setup

Hi,

if you raise up the input voltage to a higher voltage than 15 volt, the current limit function won't work anymore. I've used the same schematic as you did. Only changed the input voltage. I also simulated the schematic in the data sheet what is designed for 7-55 volts. With the same current limit, but it doesn't work.

Hi,

Sorry wrong pictures, here are the good ones:

Hi Daniel,

You can easily modify the schematic to make it similar to the circuit I have simulated. 

Change Vin to 25V

Change R3 to 1k

Change R5 to 1.5m

Change R1 to 47k

Change R2 to 1.8k

Change R6 to 1

Add a time controlled switch and another 1 ohm resistor in paralell with R6 to make a load step

What I have seen (also with LTSpice) is that when the input voltage is below the target output voltage the circuit will not react to an overcurrent situation.

Your help is much apreciated.

Best regards,

Ola 

Hi Abdel,

Thank you! Scaling the design for a lower voltage could be a workaround to be able to simulate it. But it should be fairly easy for TI to fix this in the model!

Best regards,

Ola