A precision 5-V reference voltage performs several important functions. The reference voltage is divided down internally to 2.5 V and connected to the error amplifier’s noninverting input for accurate output voltage regulation. Other duties of the reference voltage are to set internal bias currents and thresholds for functions such as the oscillator upper and lower thresholds. Therefore, the reference voltage must be bypassed with a ceramic capacitor (CVREF), a 1-µF, 16-V ceramic capacitor was selected for this converter. Placement of this capacitor on the physical printed-circuit board layout must be as close as possible to the respective VREF and GROUND pins.