SNVSCC4A October 2023 – September 2024 LP5811
PRODUCTION DATA
The LP5811 uses a quasi-constant 1.0MHz frequency pulse width modulation (PWM) at moderate to heavy load current. Based on the input voltage to output voltage ratio, a circuit predicts the required on-time. At the beginning of the switching cycle, the main switching low-side FET is turned on. The input voltage is applied across the inductor and the inductor current ramps up. In this phase, the output capacitor is discharged by the load current. When the on-time expires, the low-side FET is turned off, and the high-side rectifier FET is turned on. The inductor transfers its stored energy to replenish the output capacitor and supplies the load. The inductor current declines because the output voltage is higher than the input voltage. When the inductor current hits the valley current threshold determined by the output of the error amplifier, the next switching cycle starts again.
The LP5811 has a built-in compensation circuit that can accommodate a wide range of input voltage, output voltage, inductor value, and output capacitor value for stable operation.