SLVSG51A April 2021 – February 2022 TPS23882B
PRODUCTION DATA
The TPS23882B features two types of foldback mechanisms for complete MOSFET protection.
During inrush, at channel turn-on, the foldback is based on the channel voltage as shown in Figure 9-2. Note that the inrush current profile remains the same, regardless of the state of the 2xFBn bits in register 0x40.
After the channel is powered and the Power Good is valid, a dual-slope operational foldback is used, providing protection against partial and total short-circuit at port output, while still being able to maintain the PD powered during normal transients at the PSE input voltage. Note that setting the 2xFBn bit selects the 2× curve and clearing it selects the 1× curve. See Figure 9-3.
In addition to the default foldback curves, the TPS23882B has individually enabled alternative foldback curves for both inrush and powered operation. These curves have been designed to accommodate certain loads that do not fully comply with the IEEE standard and requires additional power to be turned on or remain powered. See Figure 9-2 and Figure 9-3.
If using the Alternative Foldback curves (ALTIRn or ALTFBn = 1), designers must account for the additional power dissipation that can occur in the FETs under these conditions.