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Original question:

UCC28251： current mode control or voltage mode control

UCC28251: UCC28251 Current mode control: ILIM pin connection?

Subin Thekkan
Prodigy 10 points
Part Number: UCC28251

Dear team,

We are using UCC28251 for isolated High voltage DCDC converter with voltage mode control. Now we are planning to use the device in current mode control.,

for voltage mode control, we have connected the ILIM pin to current transformer circuit with resistor of 7.5ohm (assuming primary peak current of ~6A).

So For peak current mode control, RAMP/CS pin is connected directly with the current signal generated from a current transformer. resistor value is calculated as per the design specification mentioned in 8.3.7.2., which is 10ohms for Iload max of 30A  and CT ratio of 100:1. (hope this is correct, considering Output max load of 30A). Does the current signal also need to be directly connected to the ILIM PIN or i need to short ILIM pin to ground.?

Regards

Subin