JAJSE40A October 2017 – February 2018 UCC28780
The peak current threshold of the OPP curve is used to initiate the 160-ms timer, while the peak current limit (PCL) determines the highest controllable peak current of the peak current loop, VCST(MAX) = 0.8 V. In other words, this feature provides the highest “short duration” peak power (PO(MAX)) that the converter can reach. For example, to supply a highest peak power of 150%, RCS should be chosen to ensure that the peak current at 150% load and VBULK(MIN) must not be above VCST(MAX). Then, the threshold of the OPP power (PO(OPP)) can be programmed to around 112% to support 150% peak power design, based on the following equation. Additionally, before VO reaches steady state during a VO soft-start, the highest VCST can also reach to VCST(MAX). The transformer must have enough design margin separating its maximum flux density from the saturation limit of the core material under the peak current level in PCL.