SLUS829G August 2008 – February 2020 UCC2897A
This input monitors the incoming-power source to provide an accurate-overvoltage protection with user-programmable hysteresis for the power supply controlled by the controller. The circuit implementation of the overvoltage-protection function is identical to the technique used for monitoring the input-power rail for undervoltage lockout. The circuit implements an accurate threshold and hysteresis using only one pin. The input voltage of the power supply is scaled to the precise 1.27-V threshold of the overvoltage-protection comparator by an external-resistor divider (RIN3, RIN4 in ). Once the input threshold of the line monitor is exceeded, an internal-current source gets connected to the LINEOV pin. The current generator is programmed by the RDEL resistor connected to pin 1 of the controller. The actual current level is given in Equation 9.
As this current flows through RIN4 of the input divider, the overvoltage-protection hysteresis is a function of IHYST and RIN4 allowing accurate programming of the hysteresis of the line-monitoring circuit.
For more information on how to program the overvoltage protection, refer to the of this datasheet.