UCC2803-Q1: CS Pin Functionality

Jacob,

Is the voltage divider providing a DC offset to the current sense voltage?

Yes

To design this, need to make sure the absolute peak is below the 1V current limit threshold?

Yes

What’s the difference between the 1V current limiting and the 1.5V threshold for overcurrent?

The 1V comparator is used for cycle by cycle peak current mode control. The 1.5V comparator is only for overcurrent protection

Regards,

Steve M

Hi Jacob,

Yes.  In section 9.3.11 a DC Offset is being added to the current sense signal so the system will trip-out on a smaller signal from the CS resistor.

I think you're looking at the following 2 specifications:

The first specification is for the control loop.  Notice the test condition, "COMP=5V".  What this means is when the error amp (COMP pin) saturates to 5V the current sense signal can be up to 1V.  See the PWM comparator and the 1V Zener clamp in the block diagram below.

The second specification is the over current threshold.  When the current sense signal exceeds 1.5V the PWM output will be shut off to protect the MOSFET.  See the over current comparator and its 1.5V threshold in the block diagram below.

Thanks for considering TI's products, and please click on RESOLVED if you accept this reply.

Thanks,

Eric