SLUS458I July 2000 – June 2024 UCC28C40 , UCC28C41 , UCC28C42 , UCC28C43 , UCC28C44 , UCC28C45 , UCC38C40 , UCC38C41 , UCC38C42 , UCC38C43 , UCC38C44 , UCC38C45
PRODUCTION DATA
VREF is the voltage reference for the error amplifier and also for many other internal circuits in the IC. The 5V reference tolerance is ±1% for the UCCx8C4x family. The high-speed switching logic uses VREF as the logic power supply. The reference voltage is divided down internally to 2.5V ±1% and connected to the error amplifier's noninverting input for accurate output voltage regulation. The reference voltage sets the internal bias currents and thresholds for functions such as the oscillator upper and lower thresholds along with the overcurrent limiting threshold. The output short-circuit current is 55mA (maximum). To avoid device over-heating and damage, do not pull VREF to ground as a means to terminate switching. For reference stability and to prevent noise problems with high-speed switching transients, bypass VREF to GND with a ceramic capacitor close to the IC package. A ceramic capacitor with a minimum value of 0.1µF is required. Additional VREF bypassing is required for external loads on the reference. An electrolytic capacitor may also be used in addition to the ceramic capacitor.